DEMOLITION

WORKS

HJ. MOHSIN ALI RAHMAN

DEMOLITIONDemolition is the opposite of construction: the tearing –down of buildings and other structures. It is contrasted with deconstruction, which is the taking down of buildings while carefully preserving valuable elements for re-use.

It is specialise work in construction process and expert is needed.

Demolition work should be designated as one of areas given priority by contractors because it creates high potential for risks to workers and the general public.

The demolition work must follow the Occupational Health and Safety Act, 1993, Construction Regulation, 2003, 12. Demolition Work

Demolition can be classified into two which is fully demolition and partial demolition.

Demolition in General

• Demolition of buildings can improve immensely the surrounding environment and make way for new design. It can also contribute to the conservation of the earth's depleting stock of natural materials, in most cases 85% of demolition materials can be reduced, reclaimed, re-used and recycled.

Methods

• Hand demolition

• Demolition ball

• Wire ropes

• Pushing Arm

• Explosives

• Diamond saws & drills

• Laser

Demolition Methods

A Balling Machine

Balling machines generally comprise a drag-line type crawler chassis fitted with a lattice crane jib. The demolition ball, with a steel anti-spin device, is suspended from the lifting rope and swung by the drag rope.

Figure 2: Demolition ball

Demolition Methods

B. Hydraulic Pusher Arm

Articulated, hydraulically-powered pusher-arm machines are normally mounted on a tracked or wheeled chassis, and have a toothed plate or hook for applying for applying a horizontal force to a wall.

Figure 3: Hydraulic pusher arm

Demolition Methods

C. Explosives

If explosives are to be used for demolition, the planning and execution, include pre-weakening, should be under the control of a person competent in these techniques.

For large demolition, the competent person is likely to be an experienced explosive engineer; for smaller work, a shot-firer may be sufficient.

D. Overturning - Wire Rope Pulling

This method is the application of a horizontal force at a high level by pulling with wire ropes attached to winches or vehicles, and allowing the impact on overturning to demolish the building or structure. An adequate steel cab or cage should protect the winch or the pulling vehicle and the operator.

Safety

• Signboard-Picture of danger for people, children

• Lighting-red (warning), yellow (ready), green (blow)

• Sound-Siren

• Covering Area-Fencing, hoarding

FULLY DEMOLITION

CASE STUDY

1. Provide all available descriptions• Drawings• Site survey• Plan of survey• Plan of services• Extent

2. Obtain the necessary approvals from Territorial Authorities

3. Define of extend of the work

4. Ensure the inspection of building and record existing defects commences

5. Locate all the services

6. Locate and notify the contractor of all known hazardous condition pertaining to the site

7. Maintain a degree of supervision and co-ordination

GENERAL REQUIREMENT

1. GENERALCheck the site, building or structure and its contents for likely hazards

2. ADJOINING BUILDINGS Relationship and the condition of the adjoining building that can affects by the demolish

3. USE OF THE BUILDINGUsed of building in the past, may be dangers from explosive or flammable substances, toxic substances, lead, asbestos and radioactive substances

4. PUBLIC SERVICES Underground or above ground, such as gas, water, electricity, drains, telephone cables, etc, must be relocated

5. DANGEROUS STRUCTURESType of construction and the cause of the damage or weakness

PRE-DEMOLITION CHECKS (SITE INSPECTION)

1. BUILDING PLANS • Examine all available plans of the buildings where

necessary 2. ROOF • Check the condition of roof trusses and identify and

mark any bracing that is essential for its stability

3. WALLS • Identify and mark load-bearing walls and check

whether party or cross walls are properly bonded into front and rear walls

4. CANTILEVERED STRUCTURES • cantilevered structures such as staircases,

balconies, and cornices etc, which are fixed to a building

5. CONCRETE STRUCTURES • signs of damage due to the corrosion of

reinforcement or damage to the concrete

PRE-DEMOLITION CHECKS (STRUCTURAL INSPECTION)

DEMOLITION PROCEDURES

1. GENERALAll temporary works and protective structures, including hoardings, gantries. Screen, and scaffolds and propping should be erected before demolition begins, and maintained in good order throughout the duration of the work

2. DISPOSAL OF DEBRIS AND WASTE MATERIAL Demolished material should be lowered to the ground and the debris sent down in skips or enclosed chutesWhen loading trucks or trailers, care must be taken not to spill debris over the far side of the truck or trailer

3. FIRE PREVENTION

Combustible material in the vicinity of welding or cutting work shall be removed to a safe place

4. BUILDING • To prevent injury from broken glass, all glass must be

removed from windows before demolition begins

• Opening in walls, floors and stairways, through which people could fall, must be boarded up or be provided with the guardrail and toe board

• Notices erected to warn of he danger at each point entry

• All stairs or installed ladder must be checked before use

• When dismantling pitches roof trusses, the last frame should be guyed before the second last truss is removed, because its stability depends on the support from adjacent members

• Avoid free-standing walls by reducing the building in small lifts

• Remove a small section first in order to determine the direction of the main steel when demolish reinforce concrete Floor

• Column must be guyed before cutting or weakening the base, so that their fall may be controlled

1. Hand Tools2. Cranes3. Backhoe4. Excavators5. Bulldozer6. Catch Screen 7. Chute8. Hoarding

PLANT & EQUIPMENTS

9. Backhoe 10.Machine-Lifted

Platform11.Gantry12.Propping13.Pulling rope14.Pusher Arm15.Scaffolding16.Toe Board

Type of equipment that used for demolition purposes :

• The Demolition work should start from from top-most floor and moving down right to the ground floor

DEMOLITION METHOD

Excavator At The Top Of Building

Con’t…

Water sprayed regularly to ensure the area not covered by dust from the demolish process

Water taken from the tank at the base by using booster pumps

Con’t…

Dust Control Using Water

The Excavator Demolish At The Lower Floor

Con’t…

The Hydraulic Excavator

Con’t…

Debris

Inspection Of Underground Services

Cut Off The Power Supply By TNB

Services Cable Under The Building

Con’t…

Con’t…

• Scaffoldings would be removed gradually floor-by-floor together with safety net

• When the demolition works reach 6th floor all the three machineries would then be removed out of the building

• The demolition work would continue from the ground level using MS 300 Long Arm Hydraulic Excavator besides two units of Komatsu PC300 Hydraulic Excavator

Debris from the demolition works at 6th floor downward would then be removed using dump trucks from four specified collecting point

Con’t…

Other Parts Of Building

• Contractor should take a number of steps to safeguard the health and safety of workers at the job site

• Involve the overall planning of the demolition job

• All planning work should be performed by a competent person experienced

SAFETY PRECAUTIONS

DURING DEMOLITION

• Person falling from hight because of unprotected Workplace

• Person being struck by falling objects• The building collapsing suddenly• Insecure materials• Plant being used on elevated slabs without

proper precautions

Safety precautions must be taken to safeguards persons working on the site and members of the public

1. GENERAL In past accidents has caused

The contractor will ensure that the competent person is in constant charge of the demolition

while it is being carried out

2. SUPERVISION Con’t…

• Safety equipment protects only if it is being used in accordance with the supplier’s instructions

• Number of hazards in demolition work required the use of personal protective equipment

• Employees are provided with, and use, protective clothing and equipment, goggles, face shields, hearing protective devices, safety belts, gloves and appropriates respirators for dust or chemicals

3. PERSONAL PROTECTIVE

EQUIPMENT (PPE)

Con’t…

Ensure that no unauthorized persons are allowed

on to the site during demolition

4. UNAUTHORIZED ACCESS TO SITE

Con’t…

Ensure that no unauthorized persons are allowed

on to the site during demolition

5. NOISE CONTROL

Con’t…

Ensure that necessary precaution are taken to protect their employees,

the general public and occupiers of adjoining property from harmful

noise

5. NOISE CONTROL

Con’t…

Demolition works often creates large volumes of dust, which, in windy, busy or densely populated areas

must therefore be carried out frequently

6. DUST CONTROL

Con’t…

DEMOLITION SAFETY CHECKLIST 1. BEFORE WORKS STARTS

• Inspections of building by competent persons• Recognize all public

services• Demolition plan or method

statement preparation• Load bearing capacity

checking• Props, scaffold, fencing,

protective screens, lighting, danger notices, fire protection equipment arrangement

• Local authority permission

Appointed competent supervisor experienced in demolition work• Notified the neighbors

2. DURING THE COURSE OF THE WORK

• The site properly enclosed and is protective screen erected

• Erected of danger noticesSufficient propping to prevent premature structural collapse or damage to adjacent

property• All ladders, cranes, cables and other

equipment in good order.Any floors in danger of being overloaded

• All protective closing and equipment used

• Pedestrians adequately protected• Sufficient watering taking place to

keep down dust• Sufficient fire extinguishers or other

fire fighting equipment on site, and easily accessible.

Con’t…

DEMOLITION AND ALTERATION

1. Taking Out Door & Frame• Taking off door, taking out frame, lining,

architraves and all associated joinery

1. Taking Out Window & Frame• Taking off window, taking out frame, lining,

architraves, shutters, shutters boxes and all associated joinery

1. Taking Out Sanitary Fittings• Taking out sanitary fittings complete with bracket,

bearers, backboards, drainer.

• All materials arising out of the demolition and alteration work shall become a property of the Contractor

• The Government shall be entitled to purchase salvaged materials from the Contractor

1. MATERIAL

Demolitions are to be carried out in such manner and sequence as to cause

the least impossible disturbance to those parts of the works, which are to

remain

2. WORKMANSHIP

Contractor will responsible for the full protection of those parts of

the buildings which are to remain including the provision of

temporary dust-proof screen, tarpaulins and dust sheet

3. PROTECTION

Dimensions of the building and other structures to be demolished, where given in the description of works, are approximately and are

for guidance only

4. DIMENSIONS

ADVANTAGES1. Fully demolition more easier than

partially demolition because there is no refurbishment or alteration work in the building

2. Time that use for work is reduced differ to partially demolition because not like partially fully will demolished all the building without any alteration

3. There is less proper planning to do because not like partially

demolition that consist refurbishment some part of the building

DISADVANTAGES

1. The fully demolition will cause ecstatic and historical value of the building will vanish

2. Heavy machinery used when demolition work related with high building

3. Demolish work will consist a specialist contractor, chartered engineer and skilled workers

Case Study

PARTIAL DEMOLITION

Case Study 2Partially Demolition

PARTIAL DEMOLITION

Case Study – No. 18, Jalan Pos Baru, 41300 Klang Selangor D.E.

Case Study

• Proposed building – Klang

• Built in 1929 which is had been almost 76 years old

• Historical building – ages and architectural characteristic of its own

• Type – shop houses which is owned by Mr. Hai Soon

INTRODUCTION

• Function – used as a books and stationery dealer running by Mr. Hai Soon over past 30 years ago

• Mr Hai Soon – has done only some changes for interior design of his shop, so far the external facade remains untouched

Functions

THE PRELIMINARY SURVEY

BLD460-CONSTRUCTION TECHNOLOGY

PARTIAL DEMOLITION

THE PRELIMINARY SURVEY

The age, method of construction and condition of the building will all have a great influence on the contractor’ choice for demolition method, on his decision as to what items should be retained, and of course on the likely cost of the work.

INTRODUCTION

THE PRELIMINARY SURVEY

PUBLIC SERVICES.

The exact location must be found of all services on the site and whenever possible these should all be plotted on a site plan.

EXISTING BOUNDARY FENCES.

Arrange existing fences prior to demolition and site clearance.

1. drainage2. electricity supply cable3. gas pip work4. water supply pipes5. post office telephone cable6. radio and television relay lines.

THE PRELIMINARY SURVEY

The services may include;

THE BUILDING TO BE DEMOLISHED

factors that should be investigated:The type of ground on which the structure is erected.Items which can be salvaged and retained for use.

Basements, cellars,etc.Partial demolition

Well, and underground storage tanks.Previous uses of building and sites.

Lightning conductors.Street closures of diversions.

Noise, dust, and other nuisances.Hoardings and scaffolding.

THE PRELIMINARY SURVEY

PRE-DEMOLITION PROCEDURE

BLD460-CONSTRUCTION TECHNOLOGY

PARTIAL DEMOLITION

PRE-DEMOLITION PROCEDURE

1) Permission from the local authority

2) Erect hoarding – access and exit to site

PRE-DEMOLITION PROCEDURE

3) Mark point selected of the pre-stressed member that needed to be demolished

PRE-DEMOLITION PROCEDURE

PRE-DEMOLITION PROCEDURE

4) Item to be salvaged – take out from the site (roof,window,door,etc)

PRE-DEMOLITION PROCEDURE

5) Temporary support (facade - dead shore – window)

PRE-DEMOLITION PROCEDURE

5) Temporary support (facade - dead shore – window)

PRE-DEMOLITION PROCEDURE

Back process (from roof – wall – floor)

Frame for pre-stressed concrete structural member any cutting work can only be done at selected point by experienced chartered engineers.

6) Determine the sequence of work.

Method & procedure of partially demolition

BLD460-CONSTRUCTION TECHNOLOGY

PARTIAL DEMOLITION

Method & procedure of partially demolition

1.0 Permission

getting permission from local authority

2.0 Salvaged item

Salvaged or retained material& structure on building

•electrical wiring & conduit

•Door & window frame

•Piping and roof covering

Marking point at the selected component that need to be demolish

3.0 Marking Point

Method & procedure of partially demolition

4.0 Shoring systemErect temporary structure support shoring system- types of shoring is steel raking shores

Method & procedure of partially demolition

5.0 Safety precaution

• Fencing/ Hoarding- to prevent any trespasser entering the demolish area

• Safety net- avoid debris or demolish waste fell into public

• Safety signboard- as a precaution on safety and hazard on site

Safety net

Hoarding

Method & procedure of partially demolition

6.0 Demolition works

Demolition work will be proceed after all the requirement is fully secured. Start demolish with the upper floor and continued until staircase by using hand tool percussion for example concrete driller, pneumatic tools etc

Method & procedure of partially demolition

PRE DEMOLITION WORK

PARTIAL DEMOLITION

Check list prior to demolition• Site visit – architect who one was

involved in this project.• Method construction for this

demolition by using hand tool to hack the building.

• The size of the demolition activity has very little bearing on the risk and required management control

• Previous use of premises – in this case study the premises was book store.

• Fencing, Shoring, Scaffolding- Considered as a high risk activity, which requires a systematic approach to planning, control and execution of the work.

PRE DEMOLITION WORK

a) Protective clothing- the component for the building need to supply the safety equipment like shoring, scaffolding and netting were use to prevent any material from the building through out to the building.

b) Fencing, shoring and scaffolding must be protected and service to prevent any damage in that component.

c) Men on site- the labour must physically well prepared before entering the site.

d) Equipment & Machinery – in this case only use hand tool like hacker, drill and lorry should well maintain.

e) Disposal rubbish- the rubbish from the building will thrown away from the site.

f) Dust- the water was use to avoid the dust circulate before spread away from the site.

PRE DEMOLITION WORK

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