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NATIONAL BUILDING GUIDE FOR LIGHTLY LOADED STRUCTURES IN DISASTER PRONE AREAS IN GHANA
COMPILED BY
JOHN TETTEY
CONSULTANT
JULY, 2011
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TABLE OF CONTENTS
PREFACE
A. INTRODUCTION B. SITE
3.0 SITE INVESTIGATION AND PREPARATION
3.1 Site selection
3.2 Ground Investigation
3.3 Site preparation
C. SUBSTRUCTURE
4.0 FOUNDATIONS
4.1 General
4.2 Classification of foundations
5.0 EXCAVATION AND EARTHWORKS
5.1 Setting-out of foundation
5.2 Excavation
5.3 Backfill
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5.4 Hardcore filling
D MATERIALS
6.0 Formwork 6.1 Materials 6.2 Beam formwork 6.3 Wall and column formwork 6.4 Stricking time for insitu works 6.5 Boardmarked formwork 6.6 Plywoodmarked formwork 6.7 Sawn formwork 6.8 Inserts 6.9 Precast concrete formwork
7.0 Cement 7.1 Specifications 7.2 Types 7.3 Storage 7.4 Clay pozzolana
8.0 Aggregates 8.1 Coarse aggregate 8.2 Fine aggregate 8.3 Alkali aggregate 8.4 Storage aggregate
9.0 Water 9.1 Water/cement ratio
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10.0 Concrete
10.1 Classification of concrete mixes
10.2 Designed mix
10.3 Prescribed mix
10.4 Durability
10.5 Basic Tools for concrete works
10.6 Concrete trial mixes
10.7 Transportation of concrete
10.8 Placing concrete
11.0 Steel for reinforced concrete
11.1 Recommended types
11.2 Sizes of Reinforcements
11.3 Placing Reinforcements
11.3 Bending Reinforcements 11.4 Placing Reinforcements 11.5 Cover of concrete
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12.0 Masonry (Sandcrete Blocks , Bricks ,landcrete or stabilized earth)
12.1 Scope
12.2 Required reinforcements
12.3 Masonry units
12.4 Testing of Blocks 12.5 Blocklaying 12.6 Burnt Clay Bricks
13.0 Mortar
13.1 Lime
13.2 Mortar Mixes
13.3 Mortar Joints
14.0 Waterproofing and dampproofing
14.1 Waterproofing of walls
14.2 Dampproofing of walls
E. SUPERSTRUCTURE
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15.0 MASONRY JOINTS AND SUPPORTS
15.1 Solid Masonry Joints
15.2 Hollow Masonry Joints
15.3 Contraction and expansion joints
15.4 Masonry Support
15.5 Wall Thickness and Height
15.6 Masonry Veneer
15.7 Columns
15.8 Lintel
16.0 STAIRCASES 16.1 Private Stairways 16.2 Common Stairways 16.3 Landings 16.4 Insitu Concrete Steps 16.5 Single Steps supported from a Central Loadbearing Column 17.0 ROOFING 17.1 Roof Protection 17.2 Roofing Nails 17.3 Roofing Staples 17.4 Roof Slope 17.5 Flashing at Intersections
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17.6 Types of Roofing 17.7 Trussed Rafters 17.8 Roof Ridges 17.9 Corrugated Sheets 17.10 Flat Pan Tile Roofing 17.11 Protection of roof against windstorm 18.0 CARPENTRY AND JOINERY 18.1 Timber 18.2 Nails and Screws 18.3 Ceiling 18.4 Doors 18.5 Windows F. FINISHES 19.0 WALL AND FLOOR FINISHES 19.1 Wall Tiles 19.2 Flooring 20.0 IRONMONGERY 20.1 Screws 20.2 Locks 20.3 Hinges 20.4 Welding 21.0 PLUMBING INSTALLATION 21.1 Portable Water 21.2 Piping Facilities 21.3 Sewerage and Waste Disposal 21.4 Soil Pipes 22.0 ELECTRICAL INSTALLATION 22.1 Distribution 22.2 Fuses 22.3 Circuit Breaks
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22.4 Earthing 22.5 Cables 22.6 Lighting Outlets 22.7 Emergency lighting 22.8 Lighting arrester 22.9 Fire safety 23.0 PAINTING 23.1 Primers 23.2 Mixing 23.3 Preparation for Commencement of Work 23.4 Protection of wet painted surfaces G. EXTERNAL WORKS 24.0 DRAINAGE 24.1 Scope 24.2 Installation 24.3 Drainage disposal 24.4 Surface drainage 25.0 RETAINING WALLS AND REVETMENTS 25.1 Types 25.2 Temporal structures 25.3 Permanent structures 25.4 Revertments 25.5 Gravity walls 25.6 Flexible walls 26.0 FENCES AND HEDGES 26.1 Common fencing materials 26.2 Concrete Fence 26.3 Steel Fence 26.4 Hedges
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1.0 PREFACE The National Disaster Management Organization, (NADMO) was established by Act
517 of 1996 to manage disasters and similar emergencies in Ghana. The Act inter alia,
makes NADMO responsible for the implementation of Government policy on Disaster
Prevention, Disaster Risk Reduction and Climate Change Management as well as the
implementation of National, Regional and District Disaster Management Plans.
It is known worldwide, that most natural and man-made disasters are exacerbated or
mitigated by the nature of houses and structures in affected communities and NADMO,
as far back as 1998 recognized the need for hazard resistant buildings, especially
earthquake and flood resistant structures in earthquake and flood prone areas in the
country. NADMO also recognizes the need for building regulations and codes that
adequately incorporate standards for the design and construction of buildings in disaster
prone areas.
In Ghana currently, there is serious indiscipline in the building industry resulting from: :
Inadequate or non-enforcement of existing building regulations and by laws Lack of building inspectors
Decline in the use of the services of professionals in the building industry and
most dwelling houses are built with little or no professional architectural or
engineering advice. Rate of development out-pacing the rate of plan preparation Building plots are sold and bought without reference to planning schemes.
Many buildings are sited in hazardous areas such as flood plains and on expansive soils.
This has made most buildings vulnerable to disasters especially earthquakes, fires and
floods. Accessibility to these buildings is poor and in emergencies, response agencies
are not able to operate efficiently resulting in the loss of lives and property.
NADMO, in collaboration with various stake holders has initiated action to ensure that
the National Building Regulations are revised and updated and National Building Codes
and standards adapted to regulate the building industry. A draft Building Code prepared by the Building and Road Research Institute (BRRI)
since 1990 is to be adopted as a national document and the revision of the National
Building Regulations is progressing.
In the mean time NADMO has found it appropriate to manage the situation by coming out with a National Building Guide (NBG) to equip artisans and developers with basic
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knowledge for the construction of lightly loaded structures in hazard prone areas of Ghana as part of its disaster risk reduction strategies. This guide is not meant to replace the National Building Regulations or Building Codes
when they are available. It is also not a substitute for the services of trained
professionals like Architects and Engineers. It is always safer to have trained
professionals design and construct buildings. NADMO recommends that the services of
building professionals are used as much as possible. However it has been observed that a very large number of people do not use the
services of professionals but build with the help of artisans only. The NBG is meant to
provide guidance for developers when professional help is not readily available.
NADMO wishes to express its gratitude to the United Nations Development Programme
(UNDP) and the various stake holders for their assistance in the preparation of this
building guide.
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INTRODUCTION
In recent times, there has been a trend towards increasing occurrence of natural and manmade disasters that may be associated with other environmental issues, such as:
Global climate change. Inappropriate location of structures near natural hazard zones. Increased population and population density. Growth in natural hazard zones. Urban growth. Inadequate or non-enforcement of building codes and regulations.
The consequences have increased human suffering, loss of life, and economic losses.
In response, the National Disaster Management Organisation (NADMO) was
established by an Act of Parliament (Act 517) dated September 1996 to manage
disasters and similar emergencies in Ghana.
NADMO recognises that building safer houses that could better withstand the
devastating effects of disasters contributes to disaster prevention and with the
assistance of the UNDP prepared this National Building Guide for the use of artisans
and developers in the construction of lightly loaded structures
The aim of this guide is to equip artisans and developers with basic knowledge for the construction of lightly loaded structures in hazard prone areas of Ghana.
The building guide applies to buildings of two storey’s or less in build building area not exceeding
220m2and which are intended to be used for residential business, mercantile and medium and low hazard industrial occupancy.
The National Building Guide gives guidance on: i. Site investigation ii. Selection of Building Materials iii. Construction of the Substructure and Superstructure iv. Finishes and External Works.
DISASTERS AND HAZARDS
Disasters that may occur in Ghana have been classified into six groups. i. Pest and Insect Infestation ii. Disease Epidemics iii. Fires iv. Hydro –Metrological
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v. Geological vi. Man-Made
Specific Hazards that need attention in building design and construction are listed in Table 1. Table 1: Hazard Types and Specific area of Occurrence in Ghana
DISASTER GROUP HAZARD TYPE SPECIFIC AREAS OF
OCCURENCE IN GHANA
Pest and Insect Termites Nationwide
Infestation
Disease Epidemics Cerebro-Spinal Meningitis Upper West; Upper East; (CSM) Northern; Volta and Brong Ahafo
Regions. Fires Bush, Domestic and Nationwide
Industrial Fires
Hydro –Metrological Rainfall-Runoff Nationwide
Hydro –Metrological River Flooding River Basins (Figure 4: Floods
Hazard Map)
Hydro –Metrological Lagoon Flooding Coastal Zones
Hydro –Metrological Tidal Flooding Coastal Zones
Hydro –Metrological Man-Made Flooding Nationwide (Hazard Mapping
(blocking of river courses; Needed) dam burst etc)
Hydro –Metrological Rain/Wind Storms Nationwide
Earthquakes Southern Ghana (Figure 1: Seismic Hazard Map)
Geological Tsunami Coastal Zones
Geological Expansive Soils Nationwide (Hazard Mapping
Needed) Geological Soil Erosion Nationwide (Hazard Mapping
Needed) Geological Coastal erosion Coastal Zones (Figure 2: Coastal
Erosion Hazard Map)
Geological Land Slide Hilly Areas of Ghana (Figure 3: Landslide Map) Geological Radon Gas Emissions Nationwide (Hazard Mapping
Needed) Man-Made Collapse of Buildings Nationwide
SITE INVESTIGATION AND PREPARATION Before a site is used for a building project, it must be investigated. Site investigation here refers to processes to:
i. Determine whether the site is earmarked or zoned for the proposed project
by the local planning authority. ii. Obtain data required for the design of the foundation of buildings.
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iii. Determine whether the site is suitable for building or the project. iv. Identify rock outcrop, landfills, vegetation, water bodies, existing underground
services etc. v. Identify the types of Hazards that exist in the area.
Avoidance is the least expensive and most logical strategy to reduce vulnerability to floods, coastal erosion, earthquakes and landslides when selecting a building site. The simplest approach to avoidance involves urban and land-use planning. Community
decision-makers should enact public policies and take actions that avoid building in
hazardous areas.
In preparing the site the top soil and vegetative matter shall be removed. Where there are termites, an ant anti-termite treatment should be applied.
SPECIAL RECOMMENDATIONS Ordinary portland cement, sand, gravel, crushed rock, reinforcement steel bars, wood,
metal roofing sheets and concrete roofing tiles are the predominant building materials
used in Ghana today.
Use of pozzolana cement, burnt brick, landcrete or stabilized earth and other local building materials that meet GSB specification should be encouraged.
Correct selection and mixing of materials are important in the construction of hazard
resistant buildings. Concrete mixes and water/cement ratio for all concrete mixes, shall
be as prescribed and the right sizes of steel must be used at all times. The use of
white core plywood should be discouraged and red core plywood used.
In Areas where a naked fire is predominant, it is not recommended to use timber for
internal and external walls. In earthquake prone areas, special attention must be
given to foundation and superstructure design and construction. Roofs need to be
wind/rain storm resistant and concrete foundations are better in flood prone areas
All electrical materials used must be approved by Ghana Standard Board or other
competent authority and electrical installations must be carried out by qualified
professionals. All buildings must have fire detection, fire alarm and fire fighting devices and be protected with a well grounded lightning arrester. All portable L.P.G bottles shall be located outside the building when in use.
The guide when used properly will make Ghana’
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FIGURE 1: SEISMIC HAZARD MAP OF GHANA
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FIGURE 2: COASTAL EROSION HAZARD MAP OF GHANA
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FIGURE 3: LANDSLIDE HAZARD MAP OF GHANA
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FIGURE 4: FLOODS HAZARD MAP OF GHANA
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B. SITE
3.0 SITE INVESTIGATION AND PREPARATION
Site investigation is the process by which geological, geotechnical and other relevant
information which might affect the construction or the performance of a civil engineering
or building project is acquired .Site investigation should be undertaken in order to obtain
data required for an Intelligent design of the foundation of buildings. The following activities are to be carriedout to prepare the site for construction:
3.1 Site selection: i) Zoning : determine whether the site is earmarked or zoned
for the proposed project. In an on unplanned area or community, seek an expert advice to determine:
ii) Suitability: Determine whether whether the site is suitable for building. iii) Surface characteristics: For the identification of surface characteristics, e.g. rock
outcrop, landfills etc. i iv.) Vegetation: identification vegetation types and species of existing trees. v) Water bodies: Identify surface water flowing on or around the site . vi) Existing underground services: Determine the location of water supply and drainage
pipes, electrical telephone and other cables. vii) Existing structures: Determine closeness of adjacent structures to site and closeness of
their foundations to the proposed building.
3.2 Ground Investigation: In the event that the site is in doubt, ground investigation is carriedout.This must be done by an expert:
a) To determine subsoil characteristics. b) To determine the load bearing capacity of the soil at various depths. c) To determine the order of settlement which is likely to occur with the established safe
load bearing pressure on the soil at various depths or with the applied pressure where
this is lower. d) To decide on the suitable construction method e) To determine the groundwater level its seasonal fluctuation . f) To identify on any harmful chemicals present in the soil or in the groundwater.
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3.2.1 Some Methods of Soil Investigations: The two methods of soil investigations are Trial pits and by Boring
3.2.2 Boring Method: This system of establishing the bearing capacity of soil is useful in areas
where it is difficult to coduct proper laboratory tests. This employs mechanical means of
of excavation of depths not exceeding 3m.
3.2.3 Trial Pit Method: Involves the excavation of shallow pits covering small planned areas, about 1mx1m
3.2.4 Types of ground: Rocks, Gravels, Laterite, Sands, soil, clays, fill.
Rocks: They are normally excellent foundation materials with high load bearing properties and negligible settlement under load.
Gravel: Are deposited loosely and can easily be removed by shovel: 50mm diameter stakes can be driven without trouble.
Literite: Has good load bearing properties. Sands: They are compact and require a pick for excavation.
Silt: Are soft soils, early moulded with fingers, or formwork.
Clays: Can be soft or stiff, hard, brittle and cohesive.
Fill: Can be composed of miscellaneous materials e.g. Mineral waste, rubble, organic waste etc. Hard pan: Well cemented gravel silty sand.
Bearing capacity: Bearing capacity of a soil is the ability of the soil to carry a load.
3.3 Site Preparation
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3.3.1 Site Clearing: The top soil and vegetable matter in all unexcavated areas for the proposed building shall be removed.
3,3.2 Antitermite treatment: Where there are termites an antitermite treatment should be
applied as follows:
(i) All termite rests on the site shall be opened up, the Queen extracted and destroyed.
(ii) The rests shall be broken open at the top and a approved chemical applied.
(iii) 3 days after treatment, the rest and the surroundings shall be totally excavated
300mm in each direction clear of the fungus gardens and filled with approved materials.
(iv) All termite runways should be traced and treated until all termite life is
exterminated.
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C. SUBSTRUCTURE
4.0 FOUNDATIONS
The foundation of a structure is defined as that part of the structure with direct contact
with direct contact with the ground and which transmits the load of the structure to the
ground.
4.1 General
A satisfactory foundation must meet three (3) technical requirements:
i) It must be placed at an adequate depth to prevent heave undermining by scour or damage from construction nearby.
ii) It must be safe against breaking into the ground. iii) It must not settle enough to disfigure or damage the structure.
4.2 Classification of Foundations
Foundations can be classified as deep foundations (caissons and piles) or shallow
foundation (strip, pad, raft/mat). For the purposes of this building guide it is
recommended to use shallow foundations. 4.2.1 Strip foundation :Strip foundation consists of continuous strip of mass concrete or other
material like stones or bricks which rests on the soil at depth and width depending on the
bearing capacity and type of soil. This is a common foundation used for load bearing wall
structures on good and average bearing soils. Strips may also be designed to span on cantilever
or soft sports in the ground.
Strip foundatios are used:
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i) Under walls, pilasters, columns, piers and chimneys that bear on soil or rock.
ii) If the foundations of a building are constructed as strip foundations of plain concrete
situated centrally under the walls, the strip foundation shall rest on undisturbed soil or rock. There shall not be a wide variation in the type of subsoil within the loaded area and no weaker type of soil below. The soil on which the foundations rest within such a depth as may impair the stability of the structure.
4.2.2 Footing Width: The width of the strip foundations shall be determined by the site conditions, the type of soil and the size of building as shown on table 4A.
4.2.3 Footing Thickness: The thickness of strip foundations shall not be less than its projection
from the base of the wall or footing and shall in no case be less than 150mm.
4.2.4 Footings laid at more than one level: Where the strip foundations are laid at more than
one level at each change of level the higher foundations shall extend over and unite with the lower foundations for a distance not less than the thickness of the foundations and in no case less than 300mm.
4.2.5 Pier, Buttress or Chimney forming part of a Wall: Where there is a pier buttress or
chimney forming part of a wall, the foundations shall project beyond the pier, buttress or chimney on all sides to at least the same extent as they project beyond the wall.
4.2.6 Pad Foundation: Pad foundation is usually square , rectangular near or circular. Pad
foundation normally support columns and piers.
4.2.7 Raft/Mat Foundation: Raft foundation consist of a continuous reinforced concrete slab
under the whole building taking up all the downward loads and distributing them over a
large enough area to avoid overstressing the soil beyond its bearing capacity. It is
recommended to be used at places where the soil have weak load bearing properties .
Raft foundations are appropriate if the sum of the individual footing base areas
exceeds about one-half of the total foundation area, if the subsurface strata contains
cavities or compressible lenses difficult to define, if resistance to hydrostatic uplift is
required.
4.2.8 Piled Foundation: Piled foundations are used in areas where settlement is greater than
acceptable or unpredictable, but where load bearing soil is formal under the poorer soil
at a depth where the use of pile would be economical.
Where pile type foundations are used, piles shall be designed to support the applied loads from the superstructure in conformance with good engineering practice.
Where piles are used as foundation system in a building of a storey in building height, the piles shall be installed to support the principal framing members and shall be spaced
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not more than 3.66mm apart along the framing, unless the piles and their footings are
designed for larger spacings. The height of such piles shall not exceed 3 times their least
bare dimension at the base of the pile. Where sandcrete block piles are used, and when
the width or the building is 4.27m or less they shall be laid with their longest dimension
at right angles to the longest dimension of the building.
TABLE 4A
TYPES OF SOILS
Condition Type of Field Test Minimum width in millimetres
Subsoil Applicable Single storey Two storey
I
Rock Not Requires at In each case equal to the width
inferior to least a
sandstone pneumatic or
or other
limestone mechanically
operated pick
for excavation
II
Gravel Compact Requires pick 250 - 400 500 - 650
Sand Compact for excavation,
wooden peg
50mm square
in cross-
section hard to
drive beyond
150mm
III Cannot be
Clay Stiff moulded with 250 - 400 500 - 650
Sandy Clay Stiff fingers and
requires a pick
or pneumatic
or
mechanically
operated
spade for its
removal
IV Can be
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Clay Firm moulded by 250 - 450 600 - 850
Sandy Clay Firm substantial
pressure with
fingers and can
be excavated
with graft and
spade
V Can be
Sand Loose excavated with
Silty Sand Loose spade.
Clayey Sand Loose Wooden peg
50mm square 400 - 600 To be caculated
in cross-
section can be
easily driven
VII
Silt Soft Fairly early 450 - 650 To be calculated
Clay Soft moulded in the
Sandy Clay Soft fingers and
Silty Clay Soft readily
excavated
VII
Silt Very soft Natural sample 600 - 850 To be calculate
Clay Very soft in rainy season
Sandy Clay Very soft exudes
Silty Clay Very soft between
fingers when
squeezed in
frost
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FIG. 5: STRIP AND PAD FOUNDATIONS
A. LIGHLY –LOADED SHALLOW STRIP FOUNDATION EXCAVATED BY HAUG OF THE SITATING A FAIRLY WIDE TRENCH, ESPECIALLY IN LOOSE SOILS DEPTY OF SHOULD BE MINIMUM 150MM, OUT NOT LESS THAN
B. LIGHTLY –LOADED DEEP AND NARROW STRIP FOUNDATION
IN CLAY, MECHANICALLY EXCAVATED, DEPTY OF STRIP ACCORDING TO AND END BEARING.
STRIP FOUNDATIONS C. STRIP FOUNDATION WITH ADDITIONAL 75mm THICK SLIDING
IN LOOSE SOIL.REINFORCED CONCRETE STRIP SHUTTERED STRENGTH A CONCRETE T-BEAM IS SUGGESTED.
POSSIBLE GROUND BEAM
PAD CAN BE SHAPED AS SHOWN BY DOTTED LINE BUT IT IS RARELY ECONOMIC DO SO FOR SMALL BUILDINGS
SECTION
THIS AREA IS SUBJECT TO UPWARD REACTION FROM S WHEN CONDERING BENDING MOMENT.
THIS AREA IS SUBJECT TO UPWARD REACTION FROM S WHEN CONSIDERING SHEAR.
PLAN 25
FIG. 6: PAD, RAFT, AND PILED FOUNDATIONS
RAFT FOUNDATIONS SOLID REINFORCED CONCRETE OR CELLULAR
CONSTRUCTION, LANDSCAPE TO PLAN, FOR SMALL
BUILDINGS 225MM THICKNESS OF RAFT FOR LARGER
BUILDING 225 TO 375MM.
AS APROX OF 1.0 TO 1.50m WITH SLIGHT FALL IS DESIRABLE
BOTTOM STEEL REINFORCEMENT RESISTS SWELLING CLAY,
6.75mm THICK COARSE SAND OR GRAVEL BUILDING IS LAID
WHEN OTHER RAFT
1. TYPICAL GROUP OF PILES UNDER A REINFORCED CONCRETE PILE CAP THERE MAY BE SEVERAL ROWS OF
P ILES EACH WAY 2. RAKING PILES TO RESIST LARGE HORIZONTAL LOADS.
UNDER-REAMED PILE FOUNDATIONS HAVE BEEN USED SUCCESSFULLY IN INDIA FOR OVER 20 YEARS IN SOILS SUSCEPT TO EXPANSION AND SHRINKAGE. LENGTH OF UNDER REAMED PILES RANGES FROM TO 8M DIAMETER OF THE MANUALLY BORED SHAFT IS FROM 200 TO 500MM DIAMETER OF UNDER-REAMED BULB IS NORMALLY 2 TIMES THE SHAFT DIAMETER
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5.0 EXCAVATION AND EARTHWORKS
5.1 Setting-out of Foundation: The approximate area for the building is excavated to a
depth of 150mm. Rough profile are set around the perimeter of the working area of the
building. Accurate setting out is required. Setting out must be especially accurate for
building with a precast concrete panel system (refer to diagram for details).
5.2 Excavation: Excavation will be classified “rock excavation” o accordance with the following definitions:
(i) Rock is defined as material of such hardness and texture that cannot be loosened
or broken by hand drifting picks, mechanical excavations including rooters, or
power-driven hand tools, but requires drilling and blasting, wedging, barring and
sledging where blasting is not permitted or unsuitable for the proper execution
of the work, and also all boulders or debris piece of rock (as defined above) more
than or a cubic metre in volume in open excavation or more than 0.4m3 volume when excavating in narrow trenches.
(ii) Excavation of all other materials, whether hard or soft, to which the definition of rock as aforesaid does not excavation”apply.shall
(iii) All excavations shall be carried out to the lines and limits shown on the excavation plan and other drawings.
(iv) The bottoms of excavations shall be leveled and trimmed to full width and shall be well watered and rammed before placing of concrete.
(v) The sides and ends of all trenches and excavations wherever necessary are to be
protected with strong, close timbering and shall prevent any fall or run of earth
or sand from any portion of the ground of the trench or excavation.
5.2.1 Bottom of excavation: The bottom of every excavation shall be free of all organic
materials. 5.2.2 Water Removed: Excavations shall be kept free of standing water 5.2.3 Disposal of excavated materials
(i) Any suitable materials removed during excavation may be used for backfill.
Materials removed from trenches shall be placed alongside the trench at a
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sufficient distance to prevent it from felling to the trench, or its weight causing the trench sides to cave in.
(ii) Rock and waste materials not suitable or not required for backfill shall be spread or removed from site.
5.3 BACKFILL
5.3.1 Placing:Backfill shall be placed to avoid damaging drainage tile or the water proofing of walls.
5.3.2 Grading: Backfill shall be graded to prevent drainage towards the foundation after
settling.
5.3.3 Boulders: backfill within 600mm of the foundation shall be free of deleterious debris
and boulders larger than 250mm diameter.
5.4 HARDCORE FILLING
5.4.1 Material: The hardcore material shall be selected granular laterite stone concrete free from rubbish and dust and broken to pass 75mm ring with sufficient smaller materials to fill interstices.
5.4.2 Beds: Hardcore beds and filling are to be deposited in layers not more than 150mm in
thickness. Each layer shall be thoroughly consolidated by ramping and rolling with heavy roller.
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FIG. 7: SETTING-OUT AND EXCAVATION SHOWING ARRANGEMENTS OF PROFILE BOARDS AND PEGS
PROFILE BOARDS AND PEGS FOR CORNERS OF THE BUILDING AND AT POSITION OF
PROFILE BOARDS AND PEGS FOR CORNERS OF THE BUILDING AND AT POSITION OF INTERNAL LOAD
A DATUM IS ESTABLISHED ON THE SITE WITH THE HELP OF A WOODEN STAKE, STEEL ON CONCRETE POST SET FIRM IN A CONCRETE BASE,
WITH THE TOP AS THE
CLOSER DATUM. ALL
LEVELS ON THE SITE
AND BUILDING RELATE
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.
D. MATERIALS 6.0 Formwork
6.1 Materials: Formwork shall be I)in every respect be adapted to the structure and to the
refused surface finish of the concrete. i) Made of sound and seasoned timber, wrought and thickness, where required and of sufficient thickness, or of steel or laminated wood, suitably supported. ii) Fixed in perfect alignment and securely braced so as to be able to withstand deflection displacement or movement of any kind. iii) Wedges and clamps shall be used wherever practicable instead of nails in the construction of the shelters. Iv) Portions of shelters at the level of each lift shall be removable to ensure the thorough cleaning out of any rubbish.
6.2 Beam Formwork:i) The bottom of all beam formwork shall have a chamber of form
1/350 of the span according to the size of the beam. ii)Beam formwork shall be so constructed such that the only portion immediately removable shall be those directly above the supporting struts. iii) All formwork shall be thoroughly and efficiently cleaned out before placing steel reinforcement and/or concrete therein. Iv) “Wash-outs” shall provided in suitable locations in the bottom of all beam formwork for this purpose. v)The inside of the formwork shall be treated with a coat of mould oil to prevent adhesion between the concrete and the formwork.
6.3 Wall and column formwork: i)Wall and column formwork shall be executed in 1500mm
lifts as concreting proceeds in order to control effectively, the deposition of concrete and to avoid segregation. ii) Where it is necessary to use spacers or ties through walk for supporting the formwork above, the spacers or ties shall be of approved pattern and have a built-in portion where are not less than 50mm from either face of the wall. iii)The holes left in the concrete shall be neatly pointed with an approved expanding grout as soon as the form work is applied. Iv) Concrete shall not be placed against vertical or inched earth faces in lieu of formwork without the approval of the Engineer.
6.4. Striking times for cast in-situ works: The time for removal of forms as set out in the Table 6.4A below shall not apply to slabs and beams spanning more than 10 metres.
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Table 6.4A
FORMS ORDINARY PORTLAND CEMENT DAY (24-HOURS)
Wall Columns (unloaded) Beam side 2
Slabs –props left under 4
Beam soffits –props left under 7
Slabs –removal of props 10
Beam –removal of props 16
6.5 Board Marked Formwork: Where board marked formwork is specified it shall be made
from 255mm wide rough sawn timber boards. The edge joints of the boards shall be covered with a 12mm x 22mm twice splayed wrought hardwood fillet to form a groove in the concrete. The resulting concrete shall clearly show grain and individual board marks, shall be free from honey-combing and excessive air holes, and shall be of uniform colour.
6.6 Wrought Formwork or Plywood Lined Formwork: Where wrought or plywood lined
formwork is specified for the concrete the formwork shall be made from plywood or such other approved material as will ensure that the finished surface of the concrete shall be perfectly true, smooth and even. Small imperfections-good” mayby rubbing with a carborundum store dipped in cement paste.
6.7 Sawn Formwork: Where a concrete surface is covered in the furnished works, the formwork shall be made from rough sawn timber boards not necessarily of uniform width. Where concrete surfaces are required to be rendered in the finished works, the concrete surface shall be scored or hacked to provide a key for the render.
6.8 Inserts: Incorporate and concrete members all electrical conduits, pipes, fixing blocks,
closes, matrices, as specified. All fixing shock, chases, holes etc. shall be accurately set out and cast into the concrete.
6.9 Precast Concretework (moulds generally)
6.9.1 Construction: The moulds shall be constructed so that the time dimensions shown on the drawing are maintained and shall withstand all loading without movement of any kind under the weight of the wet concrete and all temporary loading. Before any concrete is placed, all moulds must be checked for position and alignment.
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6.9.2 Timber Moulds: Timber moulds shall be constructed with well seasoned timber. All moulds shall be constructed so as to prevent leakage of liquid cement, remain time to shape at all times during use and give to specified finish to the unit.
6.9.3 Coating: Moulds shall be coated with approved non-standing mould oil before each unit
is cast. Care must be taken that the oil does not touch the reinforcement or accumulate at the bottom of the moulds. Before placing the concrete, all moulds must be cleaned of all concrete or mortar adhering to the surface and all rubbish, sawdust, chippings, nails and other deleterious materials must be removed.
6.10 Demoulding Unit
(i) No unit shall be demoulded before 48 hours have elapsed after coasting is
finished.
(ii) Freshly demoulded units shall be handled with the greatest of care so as to
avoid cracking and damage to the surface and arises.
(iii) All moulds shall be removed without any shock or vibration which might damage
the concrete or have any other detrimental effect on the unit. 6.11 Handling Lifting and Transporting
(i) All units shall be handled, lifted and transported in a manner which does not
cause damage or cracking. When units are lifted by crane the weight shall be taken up gradually without snatch. When units are being covered they shall not be dropped but shall be let down gently into position without impact.
(ii) No units are to be lifted until the design strength or the concrete has been
verified from cube test results.
(iii) Where the position for lifting holes or slings are shown on the drawing, they shall
not be departed from without prior permission. 6.12 Storage of Units on Site
(i) All precast units shall be stored on site in a manner and in the positions which
will prevent damage or cracking of any kind and permit erection with a minimum of preliminary handling and transporting.
(ii) All bolt holes, necessary and other cavities shall be temporarily plugged to
prevent the entry of rain or other water unless such water can freely drawn away.
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7.0 CEMENT
7.1 Specification: Cement used for cement mortar and concrete works shall be ordinary and
rapid hardening Portland cement and shall comply with GS914: 2011 (3rd Edition) Building and Construction Materials –Specification for Portland Limestone and Portland Dilomitic Limestone Cement.
7.2 Types: Some types of cement are:
i. Ordinary Portland Cement
ii. Rapid hardening Portland Cement
iii. Suphate Resisting Portland Cement
iv. White or Coloured Portland Cement
v. Pozollana cement 7.3 Storage
i. Cement shall be obtained directly from the manufacturers in sealed bags bearing
the mark of the manufacturer and shall be stored in these bags on the site in a suitable building affording adequate protection against the weather and against the ingress of moisture from any source. Rebased cement, cement in plain bags or cement in bags will not be permitted on site.
ii. The floor of the cement storage building shall be of timber at least 300mm from
the ground, the grace between the floor and the ground being kept open in order to provide adequate ventilation. The use of loose cement from the bags occasioned by any reason will not be permitted.
iii. Storage shall be arranged so that cement is used in the order in which it was
delivered so that the Engineer can rapidly identify any particular consignment for sampling and testing.
7.4 Clay Pozzolana
i. The mixing ratio of clay pozzolana and Portland cement in construction is as
shown on Table7.4 below.
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Table7.4
PRODUCT POZZOLANA AND PORTLAND
CEMENT MIXED RATIOS
Mortar 1:2
Blocks 1:2
Concrete 1:3
Plastering 1:2
Drains & Culverts 1:3
7.4.1 Directions of use of clay pozzolana
i. Mix pozzolana with Portland cement in recommended ratio in dry state. ii. Add blended cement to the sand or stones (where necessary). iii. Mix all the materials very well to form a uniform mix. iv. Gradually, add water to the materials . Ample use of water is recommended. v. Use it for your work to get a fine finish.
8.0 AGGREGATES
Aggregates can be fine or coarse and shall consist of sand, gravel, crushed rock, expanded clay. Aggregates shall be clean well-graded and free of injurious amounts of organic and other deleterious materials. Care should be taken in the selection of coarse aggregates to ensure uniformity of sizes.
The grading of fine aggregates shall be as illustrated in the Table 8.0A below:
Table 8.0A
Percentage by weight passing BSSieve
Grade Zone
1 2 3 4
5mm 90 –100 90 –100 90 –100 95 –100
No. 7 60 –100 75 - 100 85 –100 95 –100
No. 14 30 –70 55 - 90 75 –100 90 - 100
No. 25 15 –34 35 - 59 60 –79 80 –100
No. 52 5 –20 8 - 30 12 –40 15 –50
No. 100 0 - 10 0 - 10 0 - 10 0 -10
8.1 Coarse Aggregates: The coarse aggregates shall be granite, gravel or other hard stone. The nominal size of the aggregates shall be as stipulated below:
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8.2 Fine Aggregate:
Table 8.0B
Percentage by weight passing BS Sieve
BS Sieve Size
Normal size of graded Aggregate
40mm to 5mm 20mm to 5mm
80mm 100 -
40mm 95 –100 100
20mm 30 –70 95 –100
10mm 10 –35 25 –35
5mm 0 - 5 0 - 10
8.3 Alkali Aggregates Reactivity: Aggregates must not contain any matter, which is likely to undergo disruptive expansive reactions with alkali in the concrete mix or which is likely to negatively affect the long term durability of the concrete.
8.4 Storage of Aggregates
i. The fine and coarse aggregates shall be stored in properly constructed open bins
with hard clean drained floors or in such a manner that they shall not become contaminated with any deleterious extraneous matter.
ii. All sand and aggregates shall be stored on close fitting timber, steel or concrete
stage of approved design with drainage slopes or in bins of substantial construction in such a manner as to prevent segregation of sizes and to avoid the inclusion of dirt and other foreign materials in the concrete.
9.0 WATER
Water shall be clean and free of injurious amounts of oil, organic matter, sendiment or any other deleterious material. Water that is fit for drinking is to be used for concreting and should be stored in tanks, barrels near the mixed or mixing pad on site.
9.1 Water/Cement Ratio: The maximum water/cement ratio for all the concrete mixes,
unless otherwise specified shall be 0.45 except for concrete classes 22.5/38 and 10/38 which shall be 0.50 and 0.6 respectively. They shall be determined by the trial mixes and shall not exceed the values given above. Efficient means shall be provided for the moisture content and absorption values of the sand and coarse aggregate at all times.
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10.0 CONCRETE
10.1 Classification of Concrete mixes: Concrete mixes shall be classified as designed mixes or
prescribed mixes.
10.2 Designed Mix: For a designed mix, the contractor or manufacturer shall be responsible
for selecting the mix proportions to achieve the required strength and workability but the Engineer shall be responsible for specifying the minimum cement content and other properties required to ensure durability.
10.3 Prescribed Mix: For a prescribed mix, the Engineer shall specify the mix proportions and
the contractor or manufacturer shall undertake to provide a properly mixed concrete containing the constituent in the specified proportions.
10.4 Durability: The minimum cement content kg/m3 required in Portland Cement concrete to ensure durability and nominal cover to reinforcement shall be a listed in Table 10.0A and Table 10.0B respectively.
TABLE 10.0A –MINIMUM CEMENT CONTENT (KG/M3) REQURED IN PORTLAND CEMENT CONCRETE TO ENSURE DURABILITY
Reinforced Concrete
Exposure Nominal maximum size of agg-mm
40 20 14 10
Mild – for example, completely protected against
weather or aggressive conditions, except for a brief
period of exposure to normal weather conditions during
construction 220 250 270 290
Moderate –for example, sheltered from severe rain.
Buried concreted and concrete continuously under water 260 290 320 340
Severe –for example, exposed to sea, water, driving rain,
alternate wetting and drying and subject to heavy
condensation or corrosive fumes 320 360 390 410
Column 1 2 3 4
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TABLE 10.0B –NOMINAL COVER TO REINFORCEMENT
Nominal Cover –mm
Condition of exposure Concrete grade
20 25 30 40 50 and over
Mild – for example, completely protected against
weather, or aggressive conditions, except for brief
period of exposure to normal weather conditions
during construction. 25 20 15 15 15
Moderate –for example, sheltered from severe rain.
Buried concrete and concrete continuously under water N/A 40 30 25 20
Severe –for example, exposed to driving rain, alternate
wetting and drying, subject to heavy condensation or
corrosion
Very severe –exposed to sea water and with abrasion
Column 1 2 3 4 5
10.5 Basic Tools for concrete works: Guage Boxes, Spirit level, Builders severe, Wooden Float, Steel Brush, Wheel Barrow, Crowbar, Vibrator Pickaxe, Steel Moulds for test cubes, Mattock, Hollow Frustum Core, Rule, Pincers, Trowel, Builders Line, Measuring Tape, Straight Edge, Hacksaw, Bott Cutter, Headpans, Wawa Boards, Shovel, Spade, Concrete Mixer, Tamping Rod, , Pliers, Bender.
10.6 Concrete Trial Mixes: The components of concrete (cement, sand, stone and water) are often mixed in various proportions depending on the purpose for which it is intended to be used. This is done so as to achieve the minimum grade or strength for a particular concrete work. The classification of mixes, cement contents and required strength are shown below:
Table 10.0C
Minimum weight of cement for
Mix Proportion Grade Designation N/mm2 cubic metre of concrete placed
1:1:2 31.0 360 kgs/m3
1:1 –½:3 25.5 310 kgs/m3
1:2:4 21.0 280 kgs/m3
1:3:6 12.0 210 kgs/m3
The concrete for structural works shall be designated mixes which comply with the minimum requirement specified. The preliminary or trial mixes should generally give strength 25% higher than the specified “wo not less than half a cubic meter of concrete and shall be mixed in a mechanical mixer.
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The quantities of all the ingredients of each trial mix including water shall be carefully determined by weight according to the approved mix design.
10.7 Transportation of Concrete: The concrete shall be discharged from the mixers and transported to the works by means that shall prevent contamination (by dust, rain, or other causes) segregation or loss of ingredients. The means of transportation shall ensure that the concrete is of the required workability at the point of placing.
10.8 Placing Concrete: Concrete shall be used not later than thirty after it leaves the drum of
the mixer. The concrete shall be conveyed in such a way that no segregation of the constituent materials takes place. No concrete shall on any account be used after it has developed the initial set and any batch or parts of a batch which has commenced to set before being used shall be rejected. The concrete should be well worked into all corners of the formwork and between and around the reinforcing bars, to ensure compact and smooth-faced concrete.
The greatest care should be taken to prevent any displacement or bending of the reinforcing bars, ties, links and strings before commencing concreting. Care should be taken to insert or adjust members in their correct positions before concreting commences.
10.8.1 Foundation Casting: Foundations shall be cast insitu continuosouly without break making sure that the top is level. Concrete placed in timbered excavations shall be well rammed.
10.8.2 Concrete on rock surface: On rock surface a 25mm layer of 1:3 mortar shall be spread immediately prior to placing concrete and shall be well worked into the surface with the aid of brushes. All openings should be filled with concrete.
10.8.3 Blinding: Reinforced concrete shall not be placed directly on earth surfaces. Blinding shall be cast with a layer of concrete mix 1:4:8 of minimum thickness of 50mm.
10.9 Vibration of Concrete: Mechanical vibrators shall be employed where applicable for consolidating concrete. The vibrators shall operate at a frequency of not less than 5,000 cycles per minute. Freshly placed concrete shall not be vibrated in a manner likely to cause damage to concrete previously placed. All concrete to be vibrated must have a dry consistency and shall be deposited into the formwork approximately in its final position.
10.10 Curing Concrete: All surfaces of concrete shall be protected from rain, not dry and
windy weather and be kept continuously moist for several days (at least 28days) after placing. The concrete shall be covered immediately after being deposited with Hessian sacking adequately weighed down and kept through wet or with a layer of sand of other suitable material watered at frequent intervals or in some equally effective manner approved by the Engineer.
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10.11 Breaks during Construction: i Breaks in concrete casting should be avoided as much as possible.
ii. However, where it becomes necessary eg. Shortbreak for meals, then on stoppage of work. mixing machines, mixing platforms, chutes and wheel barrows used for carrying concrete shall be emptied and cleaned properly with water.
iii. Upon commencement or recommencement of work, the first batch of concrete
passed through any mixer shall contain half the normal quantity of coarse aggregate.
10..12 Joints between fresh and hardened concrete:
i. In order to obtain an efficient joint between fresh and hardened concrete the face of the latter shall be prepared by removing the surface of the hardened concrete while it is green to expose the aggregate and leave a sound, roughened surface which may be effected by spraying with water or air assisted with light brushing as necessary. If surface preparation is not carried out while the concrete is green, the surface shall be thoroughly ha cked with a power operated tool to expose the aggregate. Care shall be taken to avoid damage to the aggregate.
ii. Prior to placing fresh concrete against hardened concrete, the surface of the
hardened concrete shall be slightly moist. Vertical surfaces shall be treated with a thin layer of cement grout well worked into the surface of the hardened concrete. On horizontal joints the workability of the first batches of concrete placed in contact with the joint shall be slightly increased.
11.0 STEEL FOR REINFORCED CONCRETE 11.1 Recommended types
Stronger steel is not preferable to mild steel in earthquake prone regions. Mild steel is far preferable to higher strength steel in areas of structural members where yielding of the steel is likely(such as in potential plastic hinge zones) from earthquake loads. Mild steel is more ductile.
11.2 Sizes of reinforcements: Care should be taken in the purchase of reinforcements. A professional should be used to purchase the specified reinforcements. The normal sizes are : 6,10,12,16,20mm.
11.3 Bending Reinforcement:
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i. All reinforcement shall be carefully set to the correct dimensions in a manner, which will not damage the material. In particular no reinforcement shall be heated before bending.
ii. Bends cranks on reinforcements bars shall be carefully formed in accordance
with the bending dimensions and scheduling of bars.
iii. Reinforcement shall be stored by type, size and length in covered racks either
above ground level or on cleaned surface areas.
iv. Reinforcements shall not be joined by welding, unless indicated on the drawing.
v. Reinforcement shall be fixed in the position indicated on the drawings. The
maximum deviation of the actual position of the reinforcement from the indicated position shall be in accordance with Table 11A. All intersections of the bars shall be securely tied with malleable iron wire of suitable gauge.
Table11A - Recommended Deviations
DIMENSION MAXIMUM DEVIATION
Lateral Dimension between Bars = 12mm
Longitudinal Position of Bars = 25mm
Concrete Cover Position of Bars = 30mm
11.4 Placing Reinforcement
i. The number, size, form and position of all the bars, ties, links, strings and other
members of the reinforcement shall be in accordance with the working drawings. Nothing shall be allowed to interfere with the specified position of the reinforcement. It should be fixed by means of amended iron wire of suitable gauge to prevent displacement before and during the process of concreting. Horizontal bars in beam shall be laid parallel to each other and the stirrups shall be kept to the bars they embrace.
ii. The reinforcement may be kept in position in the framework required by means
of concrete spacers and the like. Spacers may be made of correct mortar blocks of thickness corresponding to the necessary cover. Such blocks shall not exceed 40mm length or breadth and shall be composed of one part of cement to two parts of fine aggregate.
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11.5 Cover of Concrete: Unless otherwise indicated on the drawing, the reinforcement bars shall be so placed in formwork so as to give a minimum cover of 25mm of concrete.
12.0 MASONRY ( SANCRETE BLOCKS, BRICKS, LANDCRETE OR STABILIZED EARTH) 12.1 Scope: This section applies to unreinforced masonry and masonry veneer .
12.2 Required reinforcements: Loadbearing elements of masonry buildings shall be
reinforced with at least the minimum amount of reinforcement. Masonry walls shall be reinforced horizontally and vertically with steel having a total cross-sectional area of not less than 0.002 times the cross-sectional area of the wall, so
that not less than 1/3 of the required area is installed either horizontally or vertically and the remaining in the other direction.
12.3 Masonry Units
12.3.1 Materials specifications for masonry units: Masonry units shall comply with the following GS .3921 : icks1974andblocks“ClayBS. br2028 : 1978 “Pr blocks”:GS297-1 :2010 2nd Edition “Part1 Precast Sancrete
“ 12.3.2 Used Masonry: Used bricks shall be free of old mortar, soot or other surface coating and
shall conform to article 11.4.1. 12.3.3 Stone: Stone shall be sound and durable. 12.3.4 Compressive strength: Except as provided in Article 11.4.1 the compressive strength of
masonry units in a wall of a house of one or two storey or of a building which is divided
into flats, shall have a compressive strength of not less than 2.75 N/mm2 for blocks and
5.5 N/mm2 for bricks.
12.3.5 The Compressive strength of bricks and blocks for non-loadbearing partitions shall be
not less than 1.4 N/mm2 provided the bricks and blocks are satisfactory in other respects.
12.3.6 Manufacture of Sandcrete blocks: The following is a guide for the manufacture of good
quality blocks: i. The blocks shall be composed of at least one part of cement to six parts of sand by
volume, unless otherwise specified or directed on site. ii. Mixed thoroughly until it is of an even colour and consistency throughout. iii Water shall then be added gently from watering can or through a hose, the quantity of
water being just sufficient to sense adhesiveness. iv. After wetting, the mixture should be turned over thoroughly and well rammed into
moulds and smoothed off with a steel faced tool. v. After removal from the machine on pallets, the blocks shall be matured in the shade in
separate rows one block high with a space between each block for at least 24 hours.
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vi. They shall then be removed from the pallets but shall not be stacked up or removed from the shade for at least a further 7 days. Pack them not more than 5 blocks high in the shade for a minimum of 14 days and keep them well watered at all times before use.
12.4 Testing of blocks: An experienced technician or mason can determine the quality of a good block by observation and scratching the edge of the block. Part breaks only with great difficulty and it is impossible to powder it with fingers. Cracks on the surface of a block is an indication of bad quality block and possible presence of clay in the sand used for moulding the blocks. A block could be weighed and immersed into water for 24
hours. A good block should not absorb water more than 1/6th of its weight. Also a block
that turns green easily after immersing it into clean water for about a week is an indication of low content of cement.
12.5 Block laying
i. All blocks shall be thoroughly wetted before being laid or built on
ii. Laying shall be properly bonded together and leveled through every second
course. All corners, cross wall junctions and reveal shall be properly bonded. Special care shall be taken that all vertical joints are filled with mortar.
iii. Block laying shall be carried out in a uniform manner. No one position shall be
raised more than 0.90 metres above another at any time. 12.6 Burnt clay bricks
i. Scope: Fired Clay bricks each of clay or shale shall conform to BS3921, Part2. ii. Common bricks: Shall have a thickness of 65mm, and manufactured by approved
brick and tile factory. iii. Ordinary burnt hollow bricks: Shall be 100 and 150mm thick. IV. Facing bricks: Shall be 65mm thick as selected by consultant.
12.7 Stabilized Earth Bricks
i. Stabilized laterite bricks shall be composed of sand stabilized with 5-10% cement by volume and shall conform to BS1924.
ii. Soil for stabilized laterite bricks shall conform to BS 882. iii. The size of laterite bricks shall be 290x127x90mm. iv. Curing of cement stabilized earth bricks shall be under humid conditions.
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13.0 MORTAR 13.1 Lime: Lime used in mortar shall be hydrated.
13.2 Mortar Mixes: Mortar Mixes shall conform to Table 13A. Mortar containing Portland
cement shall not be used later than two and half hours after mixing.
Table 13A
Permissible Use of Mortar Cement Lime Sand
All Locations 1 1 5 to 6
1 2 8 to 9
1 - 5 to 6
1 2 4
1 - 3
13.3 Mortar Joints
13.3.1 Thickness: The maximum average thickness shall be 13mm. Maximum thickness of an individual joint shall be 20mm.
14.0 WATER PROOFING AND DAMPPROOFING
14.1 Waterproofing of Walls: Where hydrostatic pressure occurs, floors on ground and
exterior surfaces of walls below ground level shall be waterproofed.
14.2 Dampproofing of Walls: Where hydrostatic pressure does not occur and the exterior
finished ground level is at a higher elevation than the ground level inside the foundation walls exterior surfaces of foundation walls below ground level shall be dampproofed.
14.2.1 Any part of a building next to the ground shall have a floor which is so constructed as to prevent the passage of moisture from the ground to the upper surface of the floor.
14.2.2 Any floor which is next to the ground shall be so constructed as to prevent any part of
the floor being adversely affected by moisture or water vapour from the ground.
14.2.3 No hardcore laid under floor which is next to the ground shall contain water-soluble
sulphates or other deleterious matter in such quantities as to be liable to cause damage to any part of the floor.
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E. SUPERSTRUCTURE
15.0 MASONRY JOINTS AND SUPPORT 15.1 Solid masonry joint: Solid masonry units shall be laid with full head and bed joints.
15.2 Hollow masonry joints: Hollow masonry units shall be laid with mortar applied to head
and bed joints of both inner and outer face shells. 15.3 Contraction and Expansion Joints
15.3.1 Expansion Joint Materials: Expansion joint materials shall be approved bitumen impregnated fibre board, like “Flexcel”.
15.3.2 Expansion Joint Sealer: Expansion joint sealer shall be approved cold, or knife applied sealant or
“Plastic joint” likeor“Plastic”“Sealastiand approved not applied sealed sealant. All sealers should be applied strictly in accordance with the manufacturer’s instructions.
15.4 Masonry Support: All masonry shall be supported on masonry, concrete or steel.
15.5 Wall thickness and height: Every wall shall be at least as thick as the wall it supports.
15.5.1 Thickness of solid external walls: Masonry external walls other than cavity walls in 1 storey building and top storeys of 2 storey buildings shall be not less than 125mm thick provided the walls are not more than 2.74m high at the eaves and 4.57m high at the peaks of gable ends, the external walls of the bottom storey of 2 storey buildings shall not be less than 150mm.
15.5.2 Thickness of non-loadbearing partitions: Interior non-loadbearing partitions shall be
not less than 100mm thick.
15.6 Masonry Veneer: Masonry veneer resting on a bearing support shall be of solid units not less than 76mm thick for wall heights up to 10.8m. Such veneer over wood frame walls shall have not less than a 25mm air space behind the veneer. Masonry veneer less than 97mm thick shall have unraked joints.
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15.7 COLUMNS
15.7.1 Scope: This section applies to columns used to support roofs and beams carrying loads from not more than 2 woodframe floors where the length of joists carried by such
beams does not exceed 4.88m and the live load on any floor does not exceed 2.5KN/m2.
15.7.2 Column Support: Columns shall be centrally located on a footing conforming to section
4.0.
15.7.3 Fastening Columns: shall be securely fastened to the supported member to prevent
lateral movement. 15.7.4 Steel Columns
a) Size: Except as permitted in Article 15.7.4b, steel pipe columns shall have a minimum outside diameter of 73m and a minimum wall thickness of 4.76mm.
b) Exception: Columns of sizes other than as specified in Article 15.7.4a may be used where the loadbearing capacities are shown to be adequate.(put a figure)
c) Bearing Plates: Except on permitted in Article 15.7.4d steel columns shall be fitted with
not less than 100mm by 6mm thick steel plates at each end, and where the column supports a wooden beam, the top plate shall extend across the full width of the beam.
d) Exception: The top plate required in Article 15.7.4c may be omitted where a column
supports a steel beam and provision is made for the attachment of the column to the beam by welding or other approved method.
e) Rust Prevention: Steel columns shall be treated on the outside surface with at least one coat of rust-inhibitive paint as appropriate
15.7.5 Wood Columns
a) Size: The width or diameter of a wood column shall be not less than the width of the supported member. Except as provided in article 15.7.5b, columns shall be not less than 200mm for round columns and 150mm by 150mm for rectangular columns, unless calculations are provided to show that lesser sizes are adequate.
b) Wood Columns for garages and carports: Sizes may be 100mm by 100mm.
c) Construction: Wood columns shall be either solid, glued-laminated or built-up. Built-up
columns shall consist of not less than 50mm thick full-length members bolted together with not less than 10mm diameter bolts spaced not more than 460mm, or nailed together with not less than 75mm nails not more than 300mm.
15.7.6 Solid Concrete Columns
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a) Material: Concrete shall conform to section D.
b) Size: Concrete columns shall not be less than 200mm by 200mm for rectangular
columns and 225mm diameter for circular columns.
15.8 LINTEL Masonry over openings shall be supported by steel, reinforced concrete or masonry lintels or arches designed to support improved load.
16.0 STAIRCASES
16.1 Private Stairways:
Means an internal or external stairway of steps with straight nosings on plan which forms part of a building and is either within a dwelling or intended for use solely in connection with one dwelling.
16.1.1 Any private stairway shall be so constructed that the sum of the going of a parallel step plus twice its rise is not less than 550mm and not more than 700mm.
16.1.2 The rise of a step shall be not more than 220mm and the going of a step not less than
220mm.
16.1.3 The pitch of the step shall not be more than 420.
16.2 Common Stairways: Means an internal or external stairway of steps with straight nosings on plan which
forms part of a building and is intended for common use in connection with two or more dwellings.
16.2.1 Any common stairway shall be so constructed that the sum of the going of a parallel step plus twice its rise is not less than 550mm and not more than 700mm.
16.2.2 The rise of a step shall be not more than 190mm and the going of step not less than
230mm. 16.2.3 The pitch of the common stairway shall not be more than 380. 16.2.4 A common stairway shall have not more than 16 rises in any flight.
16.3 Landings: Landings shall be at least as wide and as long as the width of stairs in which they occur, except that length of landing for exterior stairs serving not more than one dwelling unit need not exceed 610mm and the length of landing for all other stairs in a straight run need not exceed 1.12m.
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16.4 Insitu concrete steps: Insitu concrete steps should have profiles, if they have no protruding terrazzo or other covers, non-strip trips of hard rubber, carborundum metal, etc should be cast into the tread.
16.5 Single steps supported from a central load-bearing column: The precast terrazzo steps
are reinforced with 8 and 10mm diameter reinforcing roads. The erection sequence is to fix the spiral treads and to cast the reinforced concrete centre core first, second to fix the steel uprights, two to each step, third to weld the flat ms bar for the railing to the upright and last to cover the bar with the PVC profile.
17.0 ROOFING
17.1 Roof Protection: Roof shall be protected with roof covering, including flashing, installed
to shed rain effectively. Roofing materials shall conform to the following CP. 143: 1973, Code of practice for sheet roof and well coverings.
Part 15: Aluminium
Part 10: Galvanised corrugated steel
BS 402: 1974, specifications for clay plain roofing tiles and fittings.
17.2 Roofing Nails: Nails used for roofing shall be corrosion –resistant roofing or shingles
nails. Nails shall have sufficient length to penetrate through or 12mm into roof sheathing. Nails used with wood shingles or shakes shall have a head diameter of not less than 5mm and a shake thickness of not less than 2mm.
17.3 Roofing Staples: Staples used to apply wood shingles shall be corrosion –resistant and
shall be driven with crown parallel to the eaves. Staples used with wood shingles shall be not less than 28mm long; 2mm diameter or thickness, with not less than 10mm crown.
17.4 Roof Slope
17.4.1 Roof Slopes: The roof slopes on which roof covering may be applied shall conform to Table 17.4A.
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TABLE 17.4A ROOFING TYPES AND SLOPE LIMITS OF ROOFS
TYPE OF ROOFING MINIMUM SLOPE MAXIMUM SLOPE
Built-up Roofing
Asphalt base (graveled) 0 in 25 20 in 100
Asphalt base (without gravel) 1 in 25 50 in 100
Coal-tar base (graveled) 0 in 25 1 in 25
Wood shingles
Handsplit shakes
Sheet metal roofing
Corrugated metal roofing
Clay tile
Glass fibre reinforced
Polyester roofing panels
17.5 Flashing at Intersections
17.5.1 Sheet metal flashing shall consist of not less than 1.73mm thick sheet load, 0.33mm galvanized steel, 0.36mm thick copper, 0.46mm thick zinc or 0.48mm thick aluminium.
17.5.2 Valley Flashing: Where sloping surfaces or shingled roofs intersect to form a valley, the
valley shall be flashed.
17.5.3 Open Valley Flashing: Open valleys shall be flashed with not less than 1 layer of sheet
metal not less than 600mm wide.
17.5.4 Closed Valley Flashing: Closed valley flashing shall consist of sheet metal not less than
600mm wide. Nails shall not penetrate the flashing within 75mm of the top of the valley or 125mm of the bottom of the valley measured from the centre line of the valley.
17.5.5 Intersection Flashing: The intersection of shingle roofs and masonry walls or chimneys
shall be protected with flashing. Counter flashing embedded not less than 25mm in the masonry shall extend not less than 150mm down the masonry and lap the lower flashing not less than 100mm. Flashing along the slopes of a roof shall be stepped so that there is not less than 75mm head lap in both the lower flashing and counter flashing. Where the roof slopes upwards from the masonry, the flashing shall extend up the roof slope to a point equal in height to the flashing on the masonry, but not less
than 11/2 times the shingle exposure.
17.6 Types of roofing –Framed Timber roof systems
i. Couple roof
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ii. Couple roof with cellar tie iii. The mansard roof iv. The purlin system v. The rafter system vi. The Trussed Rafter –Purlin System
17.6.1 Couple roof with collar tie: It relieves the walls of thrust.
17.6.2 The mansard roof: utilizes roof space and reduces pitch. Developed with nearly flat top
in late renaissance and barque period.
17.6.3 The Purlin System: Simple purlin roofs use sawn timber purlins spanning between walls.
They are uneconomic for spans exceeding 4.8m systems of built-up purlin girders with light rafters are more commonly used.
17.6.4 The Rafter System: Unsupported rafter systems are suitable only short spans
(limitations in lengths of sawn timber) up to 6.3m, incorporating a tie.
17.6.5 The Trussed Rafter - Purlin System: This is a popular conventional roof system for
medium sized and large buildings. The light trusses are fixed to the walls at 1.8 to 2.4m centres. Purlin spacing is dictated by the roofing material, and the purlin size by the spacing adopted.
17.7 Trussed Rafters
TABLE 17A MEMBER SIZES OF SIMPLE NAILED TRUSSES
Maximum Span Bottom Chord mm Top Chord mm Web Members mm
4.90 75 x 50 75 x 50 75 x 25
6.75 75 x 50 100 x 50 75 x 25 & 75 x 50
8.50 100 x 45 100 x 45 100 x 25 & 100 x 50
17.7.1 Types of Trussed Rafters
i. Nailed King –Post truss ii. Nailed “W” Truss
49
17.7.2 Nailed King-post truss with plywood gussets: Suitable for spans up to 7.50m extending top chord individually supported (for covered verandahs).
17.7.3 Nailed “W” truss : Usingwithunclenchedplywood45mmnails, spacedgussetsat every 600mm centres. Suitable for spans up to 8.70m.
17.8 Roof Ridges
17.8.1 Types
i. Half round Ridge ii. Two-piece Ridge iii. Ventilating type of ridge capping in two-piece form
17.8.2) Half round Ridge: The roof pitch for this ridge type should be 20o.
17.8.3) Two-piece Ridge: This is a close fitting type of asbestos cement ridge capping.
17.8.4) Ventilating type of ridge capping in two-piece form: Difference flashing pieces (cable angles and pitch covers) from flat or corrugated asbestos cement and eaves fillers are available.
17.9. Corrugated Sheets
17.9.1 Types consultant should look at other types.not i. 14 Corrugations ii. 8 Corrugations
17.9.2 14 Corrugations: Sheet lengths from 1.22 to 2.44m, width: 975mm, purlin
spacing: 1150mm, side lap: 2 corrugations.
17.9.3 8 Corrugations: Sheet lengths from 1.22 to 3.05m, width: 1000mm, purlin spacing:
1150mm. Side lap 1 corrugation 200mm overlap for 1 and 2 types of sheet, laps to be sealed with martic extrusion.
17.9.4 Minimum guage for roofing sheets: Shall be 0.45mm.
17.10 Flat pan tile roofing
i. Construction: Cable roof with 150 x 50mm merge brackets, 500mm long, fixed with M.S Framing anchors to merge rafter, with build-up fascia and 150x50mm gable board for support of roof battens. 150x50mm rafters are fixed at 900mm centres to 150x75mm wall plate with MS Anchor bolt, cast into reinforced concrete ring beam. 75x50mm timber battens at 300mm centres, 75x50mm joists suspended from rafters with 50x3mm MS Hangers supporting 10mm thick particle boards. 50x15mm cover strip
50
ground edges. Bituminous paint issued under wall plate. 50x20mm vent battens covering wire netting and 150x50 special fillet piece for eavestile are fixed.
ii. In case where unit tiles are used boarding is strictly recommended with 10mm with felt to be laid as quoted in 17.10i.
17.13 Protection of roof against windstorm To protect the roof against the effect of windstorm the “bottom chord”of the roof trusses should be tied to the wall before fixing the roofing sheets. Also all the eaves of the roof should be ceiled.
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FIG.8
FIG. 9 TRUSSED RAFTERS
NOTE: The corner assembly, stud assembly at junction of interior partition with external wall (Page 151, fig. 3, 4, 5 and 6) and dimensions of nailed “W” trusses (Page 154) have been adapted from “timber frame–guidein platformconstruction frame “ (council of forest industries of British Colum “Erection of trusses” has been adapted from “notes on of building light timber trusses” (commonwealth experi building station, Dept. of Works and Housing, Crafts wood, N>S>W., Australia).
MAX. SPA BOTTOM TOP CHORD WEB MEMBERS m CHORD mm mm
mm
4.00m 75 x 40 75 x 40 75 x 25 6.75 m 75 x 45 100 x 45 75 x 25 & 75 x 40
8.50 m 100 x 45 100 x 45 100x75 &100x45 FIXED INTO PLACE
Table 15: EXAMPLE OF MEMBER SIZES OF SIMPLE HAILED TRUSSES
NAILED KING –POST TRUSS
ERECTION OF TRUSSES
THREE WORKERS ARE NEEDED. THE
TRUSSES ARE FIRST PLACED ON THE WALL PLATE HANGING UPSIDE DOWN AND TRUSS IS THEN ROTATED UPWARDS INTO THE POSITION AND
WITH PLYWOOD GUSSETS, SUITABLE FOR SPANS UP TO 7.50 M EXTENDING TOP CHORD INDIVIDUALLY SUPPORTED (FOR COVERED VERANDAHS)
NAILED “W” TRUSS WITH PLYWOOD GUSSETS, USING UNCLENCHED 45MM NAILS, SPACED AT EVERY 600MM CENTRES SUITABLE FOR SPANS UP TO 8.70 M.
GUSSET PLATES AND SPACING OF NAILS (9.5mm thick plates)
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FIG. 10
18.0 CARPENTRY AND JOINERY
18.1 Timber
18.1.1 Timber types: The recommended timber for construction are sound mahogany, opepe or other approved selected timber expressly stated by a timber expert, free from all defects.
18.1.2 Protection against termites: Timber for carpentry and joinery work shall be made thoroughly
termite-proof with approved preservatives listed in subsection 18.1.3. 18.1.3 Approved Preservatives
Tar Oils: Coaltar Creosote, Dursban, Bartoline or approved eual.
Organic solvent: Chlorinated Naphtateness, pentachlorophenol, organic datives of pentachlorophenol. Water-borne type preservatives:
These salts of such elements as copper, chromium, argenic, zinc, mercury, sodium and potassium which are dissolved in water to give a toxic solution free from deposit. The following are available: Copper/chrome, Copper/Chrome/Arsenate, sodium Pentachlorophenate, Mercuric oxide, Magnesium Floursilicate, Copper Sulphate, sodium fluoride. Dursban,bartoline or equally approved
18.1.4 Storage: Timber shall be ordered sawn and prepared as soon as practicable after the issue of
the order to commence and carefully stacked under cover so that the air will freely circulate around it.
18.1.5 Large Scantlings: Large scantling shall be sawn immediately the work commences to allow for
any shrinkage that may take place.
18.1.6 Specified scantling or unwrought work: Specified scantling or unwrought work shall in all
cases be finished sized. For wrought work the thickness specified are finished sizes after planning.
18.1.7 Ends of timbers built into walls: Ends of timbers built into walls shall have 25mm air space left
between the timber and the walling.
18.2 Nails and Screws: Oval or round brads or nails shall be used for fixing all face work and heads shall be properly punched in and neatly puttied. The size of nail to be used shall depend on the nature of work to be executed.
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18.3 CEILING
18.3.1 Construction: Suspended ceiling can be built as, jointless, in modular panels, in strips.
18.3.2 Jointless Ceilings: These are quite heavy when plastered metal lathing is used. Stretched
plastic ceiling membranes are also used or self stretchingfibre glass, reinforced P.V.C. sheeting, clipped to extruding wall fixing battens for single spans, of 4 to 15m.
18.3.3 Ceiling boards and Panels: A large variety of different insulative boards, minerals or wood
fibre panels, with their own suspension systems are used.The use of white core plywood as ceiling board should be discouraged,the use of red core plywood should be used.
18.3.4 Strip Ceiling: These are from hardwood, metal or plastic strips with their own fixing systems.
Hardwood strips are normally fixed tongued and grooved to ceiling joist. 18.3.5 Use of plywood: The use of white core plywood for ceiling is not encouraged as they become
infested with insects in no time. Red core plywood is recommended. 18.4 DOORS
18.4.1 Classification: Framed, unframed and flush doors should be well treated
18.4.2 Framed Doors: There are doors with stiles which are framed to the top middle and bottom
rails and comprise the following: Framed ledge, braced and boarded doors, framed and panel door, framed and glazed door, framed and louverdoor, sliding door.
18.4.3 Unframed Doors: These are traditional and inexpensive doors made from vertical tongued
and groove boards which are held in place by horizontal sections called ledges and strengthened by diagonal braces.
18.4.4 Flush Doors: They are semi-solid cored flush doors constructed with 100mm stiles, 100mm
top and intermediate, 150mm bottom rail and 25mm vertical stiffeners at 50mm centres and covered on both sides with 6mm plywood glued and pressed and securely fixed to wood framing. All flush doors required to be veneered on one or both sides. It should be faced with 5mm selected Hyedua veneered plywood (Grade 1 type WBP).
18.4.5 Fixing of Doors: All doors and other framed works shall be put together immediately upon the
general work being commenced, but shall not be glued and wedged up until the joinery work is prepared in readiness for immediate fixing. All joinery immediately after delivery to the site shall be stored under cover and protected from weather. Hidden faces of joinery timber shall be printed before fixing.
18.4.5 Doorway Sizes
Timber should be well treated
a) Doorway Openings: Doorway openings within dwelling units shall be designed to accommodate not less than the door sizes in Table 16.2A for swing-type doors. Where folding doors are to be provided, the same openings apply.
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Table 18.2A DOOR SIZES
MINIMUM SIZE OF DOORS
At entrance to Width Height mm mm
Dwelling unit (required
entrance) vestibule or
entrance hall 810 1.980
Stairs to a floor level that
contains a finished space
All doors in at least one line of
passage from the exterior to
the basement 810 1.980
Utility
Walk-in closet 660 1.980
Bathroom, water-closet,
shower room 160 1.980
Rooms not mentioned above,
exterior balconies 160 1.980
Column 2 3
b) Doors to public water-closet rooms: They shall not be less than 810mm in width and 1980mm in height.
18.4.6 Exterior Doors
a) Thickness: Exterior doors shall be at least 44mm thick, except that doors for secondary entrances serving single dwelling units or balconies may be 35mm thick if of solid wood, solid core or stile and rail construction. Storm or combination doors shall be at least 35mm thick for wood doors and 25mm for metal doors.
b) Unprotected Exterior Doors: Where an exterior door opening is not completely protected
from driving rain, it shall be provided with a sill that slopes to the exterior and the sill caulked with suitable caulking to prevent entry of water.
c) Steel frames for exterior doors: It shall be painted with a rust inhibitive paint or otherwise
treated before erection to prevent corrosion.
18.4.7 Interior Doors
a) Interior wood doors in dwelling units other than closet doors or cupboard doors: They shall be at least 35mm thick.
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b) Interior wood doors to rooms or spaces used for storage, laundry, drying, vestibules, recreation or water closets in apartments, buildings but not within dwelling units: They shall be at least 44mm thick.
18.4.8 Glass Doors
i) Thickness: Glass thickness and the size of glass for doors shall conform to Table 18.4A.
Table 18.4A Thickness and size of Glass for Doors
Minimum Glass Weights or Thickness Maximum Perimeter m
510gm 2.03
680gm 3.05
907gm 4.06
4.8mm 4.57
5.6mm Not limited
18.4.9 Garage Doors
a) Size: Garage doors shall be not less than 2.44m wide for one car and 4.27m wide for 2 car widths. The height of the door opening with the door in the open position shall be not less than 1.93m. For parking garages, garage doors shall be not less than 3.05m wide for one-way traffic and 4.88m for two-way traffic.
b) Wood doors: It shall be at least 44mm thick in side hinged or one piece overhead and not less
than 35mm thick if sectional overhead.
c) Steel and Aluminium doors: It shall be made with suitably braced frames clad with not less
than 0.6mm galvanized steel prepared for paint.
18.4.10 Overhead Doors: Overhead doors shall have suitable springs or counter-balances and weather stops.
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FIG. 11
FIG. 12 TYPES OF DOOR OPENINGS
SIDE-HUNG, OUTWARD OR INWARD OPENING The direction of opening is also described as clockwise or anti-clockwise.
COMBINATION OF OUT-WARD AND INWARD OPENING DOOR:
This is used where and inward opening mosquito screen is required.
SIDE-HUNG SWING DOOR, SINGLE LEAF, DOUBLE SWING: The door can also be a double leaf door. It is used in Hospitals, canteens, Restaurants, etc.
SLIDING DOORS: Many variations are possible which are determined by the choice of track. The doors are normally top hung with bottom guide, with double or triple track, or sliding in a cavity wall. A sliding door can be arranged to have folding leaves. Internal folding partitions are sliding-folding doors PEDESTRIAN OR PASS DOORS TYPES OF DOORS
TWO LEAF DOUBLE SLIDING –FOLDING DOOR DOOR LEAVES FOLDING 90º
TWO LEAF DOUBLE SLIDING-FOLDING DOOR Door leaves folding 180º .
THREE LEAF SLIDING-FOLDING DOOR: Door leaves folding 180º
CENTRE HUNG SLIDING-FOLDING DOOR WITH HALF LEAF: Door leaves folding 90º
INDUSTRIAL DOORS: Industrial doors are straight sliding doors or sliding-folding doors, Top hung with bottom guide on top hung with botton roller. SPECIAL DOORS: FLEXIBLE DOORS: These are specified for positions where the user has his hands otherwise occupied (pushing a trolley, driving a service vehicle in a warehouse etc.) AUTOMATIC DOORS: These are doors with imitating, sensing and timing devices, actuating a motor gear which physically moves
60 the door (for sliding doors, folding doors, swing doors, up and down doors and gate)
FIG. 13 FRAMED AND PANNELED DOORS
DOORS DOOR 4: FRAMED AND PANNELED DOOR Interior decorative door, the wood panels are raised and fixed tongued and grooved into stiles and rails. The door is fixed with two pairs of brass butt hinges to 125 x 50 rebated door frame. DOOR 5 : FRAMED AND PANELLED DOOR
Interior door panels are from plywood to mm thick, fixed into stiles and nails. The door is fixed with two pairs of brass butt hinges to 125 x 50 door frame. Door furniture for both doors: Lever handle and mortice lock. FRAMED AND PANELLED DOORS
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18.5 WINDOWS
18.5.1 Natural Lighting and Ventilation: This section applies to installation of windows and to the requirements for natural lighting and ventilation to be provided by windows in all buildings.
18.5.2 Window types for the tropics
i. Casement windows ii. Pivot windows iii. Sliding windows iv. Louvre windows v. Awning and projected windows vi. Security or Guard windows
a) Casement Windows: Casement windows can be used as inward opening mosquito screen together with outward opening jalousied shutter, which when closed and bolted from the inside, saves burglar-proofing, they can be made entirely from well seasoned timber without glass. Top-hung open out casements, boarded or shuttered, can be used together with an inward opening mosquito screen. Casements are fixed with casement stays. These windows achieve total window opening. They can, if so required be arranged with fixed picture windows (plain glazed). Case must be taken for easy cleaning.
b) Pivot Windows: All pivot windows should have safety catches to prevent uncontrolled
movements. Horizontal pivots can be fixed to reverse for cleaning. Pivot windows achieve about 90% of window opening. They are normally metal framed and suitable only for buildings which require no mosquito and burglar proofing.
c) Sliding Windows: Sliding windows achieve up to 50% of the total window opening. Horizontal
sliding windows must be drained through the sliding channel at the bottom of the window, if no suitable protection is provided outside against rainwater sliding down the face of the window. Sliding windows are normally metal framed windows from steel and aluminium with many different designs available. They can be produced with mosquito screens which can be clipped onto the frame from the inside and removed for cleaning. Burglar proofing has to be provided separately.
d) Louvre Windows: These are in principle a series of horizontal pivots. Louvres can be made
from timber, metalco”or Louvresglass e.whichg.-Louvre“Ecarriesarefromfixed aluminium carries are usually fixed on a timber soft frame in which mosquito and burglar proofing can be incorporated. Window achieves 90% of total opening.
62
e) Awning and projected Windows: These are typical metal framed windows with different members of ventilators which open together by normal or mechanical control. Frames can take clipped-on mosquito screens. Window frames should be fixed on timber sub frames.
f) Security or guard Windows: These windows are normally used in prisons. They are bottom
hung, inwards opening metal framed windows with vertical bars as part of the frame.
Table 18.5A MINIMUM GLASS FOR ROOMS OF RESIDENTIAL OCCUPANCY
Location Unobstructed Glass Area
Laundry, basement recreation room,
unfurnished basement or cellar 4 per cent of area served
Water-closet room 0.37m2
Kitchen:
Kitchen Space
Kitchen Alcove 13 per cent of area served
Living rooms, Dining rooms, Bedrooms and
other furnished rooms not mentioned 13 per cent of area served
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FIG. 14: WINDOWS
1. CASEMENT WINDOWS: A. slide –hung open in B. side –hung open out c. Top - hung open out
Casement windows can be used as inward opening mosquito screen together with an outward opening jalousied shutter, which, when closed and bolted from the inside, saves burglar –proofing. They can be made entirely from well- seasoned timber without glass –Top-Hung open out casement Boarded or shuttered, can be used together with an inward opening mosquito screen
Casements are fixed with casement stays. These windows achieve total window opening. They can, if so required, be arranged with fixed picture windows (Plain glazed). Care must be taken for easy cleaning.
2. PIVOTS:
d. Vertical Pivot, e. Off-Centre vertical Pivot f. Horizontal Pivot.
j. Sliding windows are normally metal framed windows from steel and aluminium with many different designs available. They can be produced with mosquito screens which
can be clipped on to the frame from the inside and
removed for cleaning burglar proving has to be
provided separately
4. LOUVRE WINDOWS: These are, in principle, a series of horizontal pivots. Louvers can be made from timber, metal and glass, e.g. “Naco” louverd in NACO-Louvre carriers from aluminium, carriers are usually fixed on a timber subframe in which mosquito and burglar proofing can be incorporated, window achieves 90% of total opening.
All Pivot windows should have safety catches to prevent uncontrolled movements. Horizontal Pivots can be fixed to reverse for cleaning. Pivot windows achieve about 90% of window opening. They are normally metal framed and suitable only for buildings which require no mosquito and burglar proofing.
3. SLIDING WINDOWS:
5. AWNING AND PROJECTED
WINDOWS: These are typical metal framed windows with different number of ventilators which open together by manual or mechanical control. Frames can take clipped-on mosquito screen window frames should be fixed on timber sub frames.
g. Vertical Sliding (Developed in the 18th 6. SECURITY OR
GUARD WINDOWS
century in Europe as “Double
h. Horizontal sliding –Two moving sashes
i. Horizontal sliding-One moving sash, one fixed sash.
j. Horizontal sliding –Two moving sashes, one fixed
sash
k. Horizontal sliding –Three moving sashes
h. Sliding windows achieve up to 50% of the total
window opening. Horizontal sliding windows must
be drained through the sliding channel at the bottom
of the window, if no suitable protection is These windows are normally used in
provided outside against rainwater running down the face
prisons. They are bottom hung, inwards
of the window.
opening metal framed windows with
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vertical bars as part of the frame
WINDOW TYPES SUITABLE FOR TROPICAL
F. FINISHES
19.0 WALL AND FLOOR FINISHES 19.1 Wall Tiles
19.1.1 Wall Tile base and adhesive: Ceramic tile shall be set in a mortar base or applied with adhesive. Plastic tile shall be applied with an adhesive.
19.1.2 Mortar for Ceramic Tile: When ceramic tile is applied to a mortar base the cementitions
method shall consist of 1 part Portland cement to not more than ¼ part lime by volume. This shall be mixed in the ratio between 1:3 and 1:5 ( not less than 3 or more to 5 parts of sand per part of cementitions material by volume). Ceramic tile applied to a mortar base shall be thoroughly sealed and pressed into place forcing the mortar into the joints while the tile is wet. 12mm screeded backing to concrete or block wall shall be provided to receive wall tiles.
19.1.3 Adhesive for Ceramic Tile: Adhesives for placing ceramic or plastic tile shall be applied to the
finish coat of plaster that has been smoothened to an even surface or to masonry provided the masonry has an even surface.
19.2 FLOORING
19.2.1 Floor Finishing Materials: Finished flooring in bathrooms, kitchens, public entrance halls, laundry and general storage areas shall consist of resident flooring, concrete terrazzo, ceramic or other types of flooring providing similar degrees of water resistance.
19.2.2 Floor Tiles: Floor tiles shall be laid and jointed in cement and sand in the ratio 1:3 floating
backing. 30mm screeded bed shall be on concrete floor to receive floor tiles.
19.2.3 Suspended reinforced concrete floor: A suspended reinforced concrete floor can be cast
monolithically in situ or it can be formed of a series of pre-cast units in the ratio 1:2:4.
19.2.4 Upper Floors: An upper floor spans between supporting structures, reinforced concrete
frames (columns and beams) or load bearing walls in the ratio 1:2:4.
19.2.5 Wood Sleepers: Wood Sleepers supporting finished flooring over a concrete base on ground
shall be not less than 25mm by 40mm and shall be treated with a soaking coat of approved wood preservative.
19.2.6 Wood Strip Flooring
a) Dimensions: The thickness of wood strip flooring shall conform to Table 19.2.5A.
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Table 19.2.5A WOOD STRIP FLOORINGS
Type of Flooring Maximum Joist Minimum Actual Structures of Flooring, mm
Spacing mm with sub-floor no sub-floor
Interior or 400 20 20
Exterior 600 20 32
Use
b) Underlay: Wood strip flooring shall not be laid parallel to lumber sub-flooring unless a
separate underlay is provided.
c) Laying of Wood Strip Flooring: If wood strip flooring is applied without sub-floor, it shall be laid at right angles to the joists so that the end joists are staggered and occur over supports or are end matched, it shall be laid so that no two adjoining strips break joints in the same space between supports and each strip bears on no fewer than two supports.
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20.0 IRONMONGERY
20.1 Screws: All ironmongery shall be fixed with screws of the same material or shall be of an
approved type for the particular fittings. 20.2 Locks: All locks and fittings are to be tested and well oiled before fixing.
20.3 Hinges:
20.3.1 Brass butt hinges with steel or brass pin are recommended. For panel doors 3 number 100mm brass hinges per door are recommended.
20.3.2 Parliament Hinge: A parliament hinge shall be used where a variation of a fixed pin hinge for
thick frames are required to open 180o 20.3.3 Storm proof butt hinge, cranked 8mm: May be used for casement windows 65mm (100mm
for doors)
20.3.4 Casement Stay: For securing an open casement window into position with stay bar and fixed
pin (fixed to frame). Normally plant or channel sections of brass or Aluminium extrusions, from 200 to 300mm.
20.3.5 Fanlight Stay: For retaining top hung vent in the open position. 20.3.6 Friction Stay: For casement windows, top and bottom, hung vents.
20.3.7 Stay pins: Depending on the joinery application different stay pins may be specified. 20.3.8 Cross tongue fastener: With hook and mortice plate.
20.3.9 Wedge type fastener: With hook plate and fastener.
20.4 Welding: All units shall be prefabricated in the shop wherever possible and only a minimum of site welding employed.
21.0 PLUMBING INSTALLATION
21.1 Potable Water: Buildings are supplied with potable water from an approved public or
community system through tributary pipelines, boreholes or handdug wells. 21.2 Washrooms: Every building must be equipped with toilet facilities.
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21.3 Piping Facilities: Where a piped water supply is available, piping for cold water shall be connected to every kitchen sink, bathtub, shower and laundry area. Piping for cold water shall be run to every water closet and hose bib.
21.4 Sewerage and Waste disposal: Building sewers shall discharge into a public sewage system
where such system is available. Where a public sewage system is not available, the building sewer shall discharge into a private sewage disposal system such as a septic tank and disposal field provided the design and installation is approved. A septic tank must be accessible for dislodging.
21.5 Soil Pipes: Soil pipes are normally 100 to 150mm in diameter, waste pipes from 32mm to
50mm in diameter for domestic appliances and 16mm for non-domestic appliances e.g. in hotels and canteens. Main sewer drain pipes vary in size.
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22.0 ELECTRICAL INSTALLATION All electrical materials used must be approved by Ghana Standard Board or other
competent authority. Electrical installation must be carried out by qualified persons.
22.1 Distribution: Electricity supply to a building could be connected either overhead or underground from a local transformer sub-station where the supply voltage from the town grid has been reduced to three phase, four wire 415/240 volt, 50 cycles per second supply. The supply is distributed by 3 time cable with a neutral wire which is earthed at the substation. The voltage between any phase wire and neutral is 240 alternating voltage. A three phase supply to a building achieves a more balanced load on the phases by serving different areas of the building with different phases.
22.2 Fuses: Use approved fuses with correct ratings only.
22.3 Circuit Breaker: These are automatic switches which turn themselves on when too much
current passes. They are easier to be turned on again than to replace or rewire a broken fuse although the later is cheaper and more useful for the self help person if fuse wire is available.
22.4 Earthing:
Buildings must be properly earthed with approved earthing material. It is recommended that where the earthing material is buried the area should not be concreted.
22.5 Cables
22.5.1 Types: Cables available are single core, twin core, twin core with earth, three core with earth.
Single Core: These have one conductor only which is enclosed in sheath of insulating material.
Twin Core: These have two conductors separately insulated and enclosed in an outer sheath of the same insulating material.
Twin Core with earth: These are two conductors and an earth wire, each separately insulated and enclosed in an outer sheath.
Three Core with earth: There are three conductors and an earth wire each separately insulated and enclosed in an outer sheath of the same insulating material.
An expert advice should be sought on the proper usage of these cables.
22.6 Lighting Outlets
22.6.1 Exterior Lighting: An exterior lighting outlet with fixture controlled by a wall switch located with the building shall be provided at every entrance of the buildings of residential occupancy.
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22.6.2 Lighting Outlets: Lighting outlets with fixture controller by a wall switch shall be provided in kitchens bedrooms, livingrooms, utilityroom, dining room, bathroom, water closet room, vestibules and hallways is dwelling units.
22.7 Emergency lighting
General
22.7.1 This section of the guide is concerned with that part of the emergency lighting necessary to enable persons to move within and escape from a building if the normal lighting fails at the time of an emergency (i.e. fire, earthquake)
22.7.2 Generally, emergency lighting by electricity should be provided in all residential, business, mercantile and medium and low hazard in industrial occupancy.
22.7.3 Emergency lighting fitted with batteries and chargers conforming to BS 5266 should be heated along all escape routes (corridors), stair landings where natural light is not sufficient and locations of possible danger / panic during a power outage
22.8 Lightning arrester All buildings must be protected with a well grounded lightning arrester.
22.9 Fire safety
Appropriate fire detection and fire fighting devices must be installed in all buildings.
22.9.1 Fire detection and alarm devices.
Table 22.9A gives basic fire detection and alarm devices recommended for various areas in the building.
Table .22.9A Fire detection and alarm devices.
Device Recommended Area
Smoke detector (battery Bedrooms, living areas
operated)
Heat detector (battery Kitchen and laundry
operated) areas
Gas detector Kitchen
22.9.2 Fire Extinguishers
Every building should have at least one 6kg dry powder and 2/3kg Co2 fire extinguishers. These fire extinguishers shall be located within travel distance not exceeding 18m and shall be mounted on a wall not more than 1.2m high.
At least one fire blanket shall be placed in the kitchen.
22.9.3 L.P.G Installation
70
All portable L.P.G bottles shall be located outside the building when in use.
22.9.4 Fire Instructions and drills Fire instruction shall be given by a competent person at such intervals as will ensure that all occupants are instructed at least twice every 12 Months.
Instructions and drills for occupants shall cover the following matters: i. The action to be taken upon discovery a fire. ii. The action to be taken upon hearing the fire alarm. iii. How to call Ghana National Fire Service. iv. How to use fire fighting equipment. v. Knowledge of the escape routes in the building.
22.9.5 Escape Routes
i. Escape routes should be arranged and located in such a manner to allow people to
move within the building and also evacuate the premises quickly and safely.
ii. Doors, exits and routes shall have standard safety signs visible day and night to direct
occupants in any emergency situation.
22.9.6 Direction of Opening of Doors
Doors should be hung in such a way that it will not obstruct any escape routes. (see fig.)
1.2m
Room 1
Room 2
Doors opening into escape route are not acceptable.
1.2m
Room 1 Room 2
71
Correct way of fixing doors along escape route.
Final exit doors should be opened easily from the inside by occupants escaping from the building Doors fixed along escape routes should be fitted with vision panel where appropriate.
22.9.7 EXIT AND DIRECTIONAL SIGNS
1. Any exit which is not a normal route of travel from a building should be indicated by notice bearing
the words “Emergency Exit in should be displaced immediately above the exit opening, where
possible. Where this is
not possible, a position should be chosen where the notice is least likely to be obstructed and most likely to be seen.
2. At suitable points along an escape route where an exit cannot be seen or where a person escaping
might be in doubt as to the location of an exit, a notice should be provided bearing, in letteringEXIT”
ofandnecessaryappropriatthe directional arrow. Such notices should be fixed in conspicuous
positions, where possible 2 metres and 2.5metres above floor level. Exit and directional notices should be internally or otherwise illuminated so as to be clearly legible.
RECOMMENDED LETTERING SIZE FOR EXIT SIGNS
Viewing distance Letter Height
< 20m 50mm
20m to 30m 75mm
30m to 40m 100mm
>40m 125mm
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23.0 PAINTING
All paints shall be the best quality obtainable and of approved manufacturer, guaranteed anti-fungus and suitable for use in tropical countries. Where possible fire resisting paint should be used on finished surfaces.
23.1 Primers: Primers shall be as recommended by the manufacturer for each type of paint, having regard to such type of paint and the surface to be coated. NOTE: All carpentry and joinery hardwood should be primed before fixing.
23.2 Mixing: Different types or brands of paint shall not be mixed together. Paint shall be thoroughly stirred up in their original containers. Kettle shall be clean and the paint kept clean and stirred during use. Any skins that may form shall be entirely removed before paint is used.
23.3 Preparation for commencement of work: Before any preparatory work is commenced all ironmongery and similar removable articles shall be removed and only replaced after the final decorative coat is dry and hard.( surface preparation means sand papering scrapping and application of putty).
23.4.1 Fittings such as switches and similar articles which cannot conveniently be removed shall be effectively covered during painting operation.
23.4.2 Floors shall be protected from droppings.
23.4.3 Painting process: Apply
i. Primer ii. Under coat iii. Finish coat
23.4 Protection of wet painted surfaces: Adequate care must be taken to protect surface while wet by the use of screens and “wet paint” si
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G. EXTERNAL WORKS
24.0 DRAINAGE 24.1 Scope: This chapter applies to subsurface drainage and to surface drainage. 24.2 Installation
24.2.1 Drain Tile: Draw tile or pipe shall be laid on undisturbed or on well comparted soil.
24.2.2 Granular Cover: The top and sides of drain pipe shall be covered with not less than 150mm of
crushed stone or other clean granular material.
24.3 Drainage Disposal
24.3.1 Drain Pipe: Drainpipe shall drain to a sewer, drain ditch or dug well.
24.3.2 Dry Wells(soakaway): Dry wells shall not be less than 4.57m from the building foundations
and located so that drainage is away from the building. Dry wells may be used only when located in areas where the natural groundwater level is below the bottom of the dry well.
24.4 Surface Drainage
24.4.1 Surface Drainage: The building shall be located or the building site graded so that water will not accumulate at or near the building.
24.4.2 Location of surface drainage: Surface drainage shall be directed away from the water supply
well or septic tank disposal bed.
24.4.3 Interference with surface drainage: Where runoff water from a drive way is likely to
accumulate or enter a garage, a catch basin shall be installed to provide adequate drainage.
24.4.4 Downspouts: Where downspouts are provided and are not connected to a sewer, provisions
shall be made to prevent soil erosion.
24.4.5 Rain Harvesting: Storage tanks for harvested rain water should be located at a
higher position than septic tanks.
25.0 RETAINING WALLS AND REVETMENTS
The construction of retaining walls and revetments are key to the prevention of soil erosion and landslides.
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25.1 Types: Temporal and Permanent Structures.
25.2 Temporal Structures: These are retaining structures which are upholding the sides of an
excavation in loose ground. 25.3 Permanent Structures: Retaining walls and basement walls.
25.4 Revertments: These are surfacing of soil banks or cutting with stones, bricks or concrete to
retain and stabilize the soil and to prevent erosion for landscaping and reservoir walls.
25.5 Gravity walls: These are walls which depend for stability on their own mass and dead weight.
They are up to 2m in height.
25.6 Flexible walls: these are walls designed in such a way that they act as a cantilever beam or
arch between fixed supports.
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FIG. 15: RETAINING WALLS AND REVETMENTS A
GRAVITY WALLS: THESE ARE WALLS WHICH DEPEND F STABILITY ON THEIR OWN MASS AND DEAD WEIGHT. THEY ARE UP TO 2M IN HEIGHT.
1. GRAVITY RETAINING WALL BUILT WITH STONES WITH GRANULAR BACK FILL AND 150MM DIAMETER WEEP HOLES AT 4M CENTRES. FACE OF WAL BATTERED 45º FOR DRY SET WALL OR 20º FOR WALLS SET IN MORTAL. 2. PROPORTIONS OF A GRAVITY WALL
3. GRAVITY RETAINING WALL IN CED CONCRETE. 4. GRAVITY RETAINING WALL BUILT WITH BRICKS, SUITABLE FOR LOW HEIGH TO 1.5M AND NO GRE PRESSURE. IF THE WALL IS TO BE TOGETHER, IT SHOULD BE BATTERED AT MAX 12 OR BUILT CURVED FROM BASE
.
5.
B. FLEXIBLE WALLS: THESE WALLS ARE DESIGNED IN SUCH A WAY THAT THEY ACT AS A CANTILEVER, BEAM OR ARCH BETWEEN FIXED SUPPORTS
CANTILEVER WALLS: THESE ARE USUALLY BUILT IN REINFORCED CONCRETE WITH DIFFERENT CANTILEVERS AS SHOWN DOTTED. THEY ARE USED FOR HEIGHTS UP TO 7.5 M CANTILEVERS, BEAM ARCH BETWEEN FIXED SUPPORTS
6. PROPOSITIONS OF CANTILEVER WALL.
THESE ARE NORMALLY USED FOR RETAINING WALLS OF GREATER DEPTH AND HEIGHT WITH VERTICAL OUT
TRESSES AND ADDITIONAL STIFFENING IN FORM OF HORIZONTAL RIBS.
. C. REVETMENTS:
BUTTRESS (INCOMPRESSION) COUNTERFORT (INTENSION) THESE ARE SURFACING OF SOFT BAGS O
CUTTINGS WITH STONES BRICKS OR CONCRETE TO RETAIN AND STERILIZED T SOUL
AND TO PREVENT EROSION76 FOR LANDSCAPING RESERVATION
26.0 FENCES AND HEDGES
26.1. Common Fencing materials: Galvanised or PVC coated chainlink and barbedwire fixed to concrete posts, timber fence, Hedges, concrete fence and steel fence.
26.2 Concrete Fence: Concrete can form a complete fence wall in form of prefabricated decorated blocks or is normally used for fence posts in conjunction with other materials.
26.3 Steel Fence: Galvanised steel bars or hollow tubes are used in areas where unclimbable
fencing is required. These rigid steel barriers can incorporate panels of different materials, PVC coated wire mesh or barbed wire.
26.4 Hedges: For shelter and covers, hedges, which bend with the wind are more successful
than rigid screens or solid fences.
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GLOSSARY
A.
Aggregate: Sand, gravel etc for mixing with cement to make concrete.
Alkali: Any of various soluble chemical bases, especially a hydroxide or carbonate of an alkali metal that combine with acids to form salts.
Arrester: To bring something to a stop.
B.
Bit: A replaceable drilling, boring, etc devise, part of a compound tool.
Bearing Capacity: ability of the oil to carry a load.
Beam: Any of the principal horizontal supporting members of a building.
Basement: The part of a building that is wholly or partly below ground level.
Backfill: Soil dug out of a hole or trench and later used to refill it.
C.
Columns: A pillar that usually consists of a square, rectangular of square shaft, a capital, and a base.
Chimney: A vertical structure incorporated into a building and enclosing a flue or flies for carrying of smoke. Especially the part of such a structure extending above a roof.
Concrete: Hard strong building material made by, mixing a cementing material e.g. Portland cement, and a mineral aggregate, e.g. sand and gravel, with sufficient water to cause the cement to set and bind the entire mass.
Cement: A powder containing lime and clay that is used as a binding agent in mortar and concrete.
Carborundum: Any of various abrasive materials (blend of carbon and carundum)
Conduit: A pipe, tube, or tile for protecting electric wires or cables.
Chase: A groove cut in a surface for a pipe, wire etc.
Corrugated: Folded into alternating parallel ridges and grooves.
Circuit: A complete path of an electric current.
Code: A systematic body of laws, especially one established by statutes. 78
Carpentry: The art or trade of a carpenter. The art of shaping and assembling structural woodwork.
Cables: An assembly of electrical wires insulated from each other and surrounded by a sheath.
Cure: Process of hardening of a material e.g. concrete etc.
Chutes: An inclined plane, channel, or passage down which things may pass.
Compression: The action of compressing or being compressed to press or squeeze something together.
D.
Deleterious: Harmful and detrimental
Drain: To carry away the surface water.
Dampproof: To make a (a wall or building impervious to damp by means of a damp course).
E.
Excavation: To form a cavity or hole in something by hollowing or digging.
Earthing: To connect (an electrical device) to earth.
Epidemics: An outbreak of a disease affecting many individuals within a population.
Extraneous: Not forming an essential or vital part, irrelevant.
Earthworks: An enforcement, field fortification, etc made of earth.
F.
Foundation: An underlying natural or prepared base or support especially the masonry substructure on which building rests.
Formwork: A wooden structure that holds concrete in place and in shape while it hardens.
Fuse: An electrical safety device that includes a wire or strip of fusible metal that melts and interrupts the circuit when the current exceeds a particular value.
Fiberglass: Glass in fibrous form used in making various products, e.g. textiles and insulation materials.
Flashing: Sheet metal used in waterproofing a roof or the angle between a vertical surface and a roof.
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G.
Graft: splice, attach, join, fix, embed, implant, insert.
Geology: Science that deals with the original structure, composition, and history of the earth, especially as recorded in rocks.
Geotechnical: Foundation underpinning, soil modification, liquefaction.
Gussets: A plate or bracket for strengthening a joint in a timber or a metal framework.
H.
Heave: In geology, a horizontal displacement, e crust.
Hydration: To cause ( a substance) to take up or combine with water or its constituent elements.
Hydrostatic: Relating to or denoting liquids at rest, or the pressure exerted by them.
Hardcore: Compacted rubble or clinker used especially as foundation or roads, paving, or floors.
I.
Ironmongery: Hardware for joinery.
Infestation: To spread or swarm in or over (something) in a troublesome or undesirable manner.
Insitu: In the natural, original, or permanent position.
Insert: To introduce something into the body of something.
J.
Joinery: The craft or trade of a joiner. Woodwork.
Joists: Any parallel small timbers or metal beams that support a floor or ceiling.
L.
Landslide: Rapid movement of rock, earth etc down a slope, or the moving mass of rock, earth, etc itself.
Lighting: The flashing of light produced by a discharge of atmospheric electricity between two clonds or between a clond and the earth.
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Lintel: A horizontal architectural member spanning and usually carrying the load above an opening.
Laterite: A usual red clay formed from rock decay and consisting especially of iron oxides and aluminium hydroxides.
Lime: A caustic solid consisting of calcium oxide and some magnesium oxide, obtained by heating calcium carbonate e.g. in the form of shells or limestone to a high temperature, and used in building and in agriculture.
M.
Matrix: A mould in which something is cast or from which a surface in relief e.g. a piece of type, is made by pouring or pressing.
Meteorology: The science of the atmosphere and its phenomena, especially weather and weather forecasting.
Mould: A cavity, dish, or form in which a substance e.g. a jelly or a metal casting is shaped. A frame around which an object is instructed.
Mortar: Mixture of cement, lime, gypsum plaster, etc with sand and water, that hardened and is used to join bricks, stones etc or for plastering.
Masonry: Something build of stone or brick.
P.
Profile: A vertical section of a soil form ground surface to the underlying material.
Pozzolana: Ash used in making hydraulic cement.
Plumbing: The system of pipes, tanks, and fixtures installed or required in supplying the water, sanitation, and heating in a house or building. Preservative: Something that preserves or has the power to preserve specifically a substance used to protect a vulnerable material against decay, discoloration, or shortage.
Purlin: Horizontal beam in a roof bracing the rafters.
Pulley: A wheel with a grooved rim that is used with a rope or chain to change the direction and point of application of a pulling force.
Precast: Of concrete or things made of concrete: cast in the form required before being placed in its final position.
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Primer: Material used in priming a surface, especially a type of paint used as first coat on plaster, wood etc.
Panels: A separate or distinct part of a surface, e.g. a thing usually rectangular board set in a frame e.g. in a door.
Preumatic: Tyre that is filled with air under pressure.
R.
Raft: A foundation slab for a building usually made of reinforced concrete.
Ridge: The line along which two upward sloping surfaces meet specifically the top of a roof at the intersection of two slopping sides.
Revetment: A facing of stone, concrete etc built to protect a wall or retain an embankment.
Reveal: The side of an opening in a wall for a door or window, especially the part that has between the frame and the outer surface of wall.
Rafter: Any of the parallel beams that form the framework of a roof.
Reinforcement: Material used to increase strength of materials especially concrete.
S.
Struts: To provide, support, or stiffer (something) with strut. A structural piece/designed to support or strengthen a framework by resisting pressure with directive of its length.
Spacers: To place (two or more things) at intervals or arrange (than) with space between.
Slab: To divide or form (something) into slabs.
Sewerage: A system of sewers. The removal and disposal of surface water by sewers.
Scantling: Small piece of timber e.g. an upright piece in the framework of a house.
Sediment:The matter which subsides to the bottom, from water or any other liquid settlings; lees; dregs.
Shale: A timely stratified or laminated rock formed by the consolidation of clay, mud, or silt.
Shingle: To cover (a roof etc) with shingles.
Sheathing: A covering of boards or water proof material on a timber roof or the metal places on a ship’s hull.
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Staple: A small piece of wire with ends bent at right angles which can be driven through thin sheets of materials.
Seismicity: Shock, earthquake, from shaking.
Substructure: Any structure that forms the foundation or framework on which something is constructed.
Sandcrete: Block made of sand and cement.
Staircase: A structure or part of a building containing a stairway. A flight of stars with the supporting framework, caring, and baldness.
Stairway: One or more flight of stairs, usually with intermediate landings.
T.
Tie: A structural element e.g. a rod or angle iron, holding two pieces together.
Tsunami: A huge sea wave that is produced byunderwater earth movement or volcanic eruption causing svere devastation if it reaches land.
Tributary: Sand of a stream or river: feeding a larger stream or river.
Terrazzo: A mosaic flooring made by embedding and polishing small pieces of marble or granite in mortar.
Trusses: An arrangement of beams rafters girders etc forming a rigid framework e.g. in a roof or bridge.
V.
Voltage: An electric potential difference, electromotive force measurement in volts.
Vibrator: A vibrating electrical apparatus used in message.
Veneer: Thin layer of wood, plastic etc of superior appearance quality, hardness used especially to give a decrative finish to cheaper material.
Vestibule: A lobby or chamber between the outer door and the interior of a building.
W.
Windstorm: Storm with high winds but little or no rain, snow, etc.
Wrought: Said of metals beaten into shape by tools.
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Waterproof: Impervious to water, especially covered or treated with a material to prevent passage of water.
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