Waterproofing in Basements

7/23/2019 Waterproofing in Basements

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WATERPROOFING IN BASEMENTS

Waterproofing is the formation of an impervious barrier, which is designed to prevent water

entering or escaping from various sections of building structures. In this regard, hydrostatic

pressure is pressure exerted or existing within a liquid at rest with adjacent bodies.

Hydrostatic pressure rises as the water table rises in the monsoon. While, for structures

located in the vicinity of a water body, the hydrostatic pressure may be permanently present.

The deeper the structure is set into the earth, greater the hydrostatic pressure will be, which

will try to force water into the pores of concrete and assist in a rapid deterioration.

Internal areas that are waterproofed include bathrooms, shower recesses, laundries and toilets.

While, external areas waterproofed extends to roofs, planter boxes, podiums, balconies,terraces, retaining walls and swimming pools.

In this paper, we shall restrict us to Waterproofing in basements!, which shall cover the

evolution, importance, role, types of waterproofing treatments, brief procedures, pros and

cons of each of this type, "ox type waterproofing treatment! which is the most popular

treatment in India, drainage in basements and the future of waterproofing.

EVOLUTION

The first real need for waterproofing dates bac# to the days of $oahs %r#. The &' days of

incessant rain inspired people to ta#e some course of action to prevent water from entering

their habitat. In the early days people relied upon thatch, such as straw, reed, leaves and other

dried vegetable matter as a barrier against water entering their home.

(ver time more sophisticated waterproofing materials were adopted. These included) animal

s#ins, timber shingles, and natural stones li#e slate. The architectural designs of the day such

as high pitched roofs helped overcome some of the shortfalls and limitations of the materials

that were used. (ver the centuries other waterproofing materials were used such as metals eg.

copper, lead, *inc, and tin.

Waterproofing has come a long way since $oah+s day. The discovery of oil, coupled with the

advances of chemistry saw the arrival of numerous petroleum derived waterproofing products

such as bituminous, butyl rubber, neoprene rubber, hypalon etc.

Technological improvements and brea#throughs are occurring on a daily basis. (ver time

today+s waterproofing membranes such as polyurethanes, acrylics and polyesters will become

as antiquated as leaves and animal s#ins are today.


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THE IMPORTANCE OF WATERPROOFING

If we refer bac# to the definition of waterproofing as an impervious barrier designed to

prevent water entering or escaping from building structures, then the importance of

waterproofing is reflected in the consequences of not waterproofing.

Water which enters or escapes from buildings can have immediate and long term undesired

effects. %part from damage to the buildings contents, structural damage is unavoidable if the

problem persists.

Water damage is second only to fire as a cause of building decay and deterioration.

urthermore, majority of building materials have a considerable shorter life span when

subjected to moisture or emersion over a prolonged period of time.

The casualties of water damage include)

- otting of timber structures and finishes such as floor joints, beams, floors, studs, s#irting,

architraves and frames.

- /orrosion of metals such as steel reinforcement in concrete, steel beams, lintels, metal door

frames etc.

- 0welling of plasterboards and the subsequent debonding of ceramic tiles.

- 1lectrical ha*ards causing the possible short circuit of lighting and power points.

- The blistering of paint.

- 2nsightly deterioration of the building facade.

- Health problems due to dampness, which may lead to respiratory problems.

- otting carpet.

The importance of waterproofing can not be overstated. The damage caused to the building+s

structure, coupled with the high cost of rectification warrants the careful design and

application of waterproofing.

THE ROLE

The role of waterproofing is to protect a building+s visual and structural integrity. It achieves

this by forming an impervious membrane that prevents water entering or escaping from wet

areas to dry areas.

In order to effectively fulfil this role a membrane must possess the following qualities)

- The membrane must be impermeable to prevent the passage of water.

- lexibility 3 membranes need to accommodate any normal movement that may occur in

building structures.


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- The membrane must be durable, it must be able to retain it+s integrity over a long period of

time.

- The membrane must lend itself to design details in a building. It must be suitable for each

specific application. The membrane is useless if it cannot be applied where needed because of

structural details.

- The membrane must be able to breathe permitting the escape of moisture vapours from

building interior and substrates.

- The membrane must be compatible with adhesives to ensure long term adhesion where tiles

are directly fixed over the membrane.

- 2ser friendly, the membrane must be easy to apply, relatively lightweight, non ha*ardous,

and environmentally safe.

- In exposed areas such as rooftops, the membrane should require little maintenance, and in

the event of damage must be easily repairable.

- It should provide a continuous film, without areas of wea#ness such as overlaps, which

could prove to be a potential source of water entry.

- The membrane must be suitable to withstand environmental and climatic conditions.

TYPES OF WATERPROOFING

There are generally two types of waterproofing membranes 3 sheet membranes and liquid

membranes. The nature of the problem to be addressed determines which type of membrane

to be used.

SHEET MEMBRANES)

The purpose of sheeting membrane is to completely cover any imperfections in the substrate

or bac#ground. They are numerous and include)

- 4etal sheets in the form of lead, copper or stainless steel flashing or trays.

- 4ultilayer bituminous paper system with gravel topping for protection.

- "utyl rubber sheeting

- 0emi3rigid asbestos asphalt sheeting

- "itumen5polyethylene sheets

- 1.6.7.4. 1thylene propylene 7iene 4onomer

- /hlorosulphanated rubber 8Hypalon9

- 6:/ 6olyvinylchloride

- $eoprene rubber


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- Torch3on sheeting consist of layers of polypropylene bitumen modified.

The sheeting membranes can be applied as fully bonded to the substrate or unbonded. The

most commonly specified sheet materials are self3adhering rubberi*ed asphalt membranes.

These ;'3mil3thic# membranes are composed of rubberi*ed asphalt laminated to a waterproof

polyethylene film. The asphalt side is incredibly stic#y but is covered by a release paper,

which you remove during application.In both cases sheets must be overlapped about


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tight and properly detailed and the correct use of the manufacturers mastic or other

accessories are made. or example, one manufacturer requires you to apply a bead of mastic

to every lap joint within


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(ne of the chief disadvantages is the possible inconsistency in coverage. The typical

application thic#ness is ;' mils, but it ta#es a careful applicator to be sure of always

achieving that minimum coverage.

egardless of which class of membrane is used, waterproofing membranes are only as good

as the applicator. 4anufacturers and distributors expect their product to be applied as

specified. ailure to adhere to their recommendations can retard the performance of the

membranes.

CEMENTIOUS WATERPROOFING:

Advantages:

/ementitious products are probably the easiest waterproofing materials to use. They+re

readily available, and they+re easy to mix and apply. =ou+ll get better bonding and a more

solid, durable coating.

Dsadvantages:

The chief disadvantage cementitious products have is that cement just doesn+t stretch to any

degree. They will stand up fine to a head of water, but will tolerate almost no joint or crac#

movement.

BENTONITE:

0odium bentonite, a clay material, has enjoyed a steady upsurge in popularity over the past

several years. In panel form, bentonite has become the choice of a growing number of

architects and builders. "entonite wor#s because it can absorb a tremendous amount of water.

%s it ta#es in water, the clay swells to


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With other products, you can inspect the finished waterproofing application and confirm the

integrity of the seal before bac#filling. With bentonite panels, the seal doesn+t form until the

foundation is bac#filled and water reaches the panel.

BO" TYPE WATER#PROOFING

or basements, 0wimming 6ools and under3ground ducts such as lift3pits, the waterproofing

has to withstand the water pressure in addition to it!s basic stress. 0hahabad "ox Type

treatment method of waterproofing is very commonly used in India.

Invention)

"hati 4ohiuddin, the founder of the $ew /onstruction Waterproofing /ompany, born in


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B$% T&'e (ate)')$$*ng *$) +ase,ents

P)$-ed.)e:

% base3coat in cement mortar


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The ground water table in the area where the basement is located, rises considerably above

the basement level in the rainy season. The water flows are also found at various depths

below the ground level.

7ue to the rise in the water table and the up thrust of the water pressure from below, the

waterproofing measures for the basement may sometimes fail and damage the basement.

%dditional measures to protect the basement are carried out for large projects or commercial

complexes as details below.

D)anage n +ase,ents

P)$-ed.)e:6athway of si*e '.;m to '.Bm width is proposed, with compacted impervious material with

specified flooring on the top. The area beyond this pathway is excavated to form a trench

throughout the periphery of the basement. The highest level of the trench is #ept at least

'.


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T1%T41$T ( (2$7%TI($0 ($ "%7 0(I>0)

Where the sub3soil water is not properly drained 8in clay or peat soil9 the structure should be

disconnected from the face of the ground excavation and a trench made all around for a width

of ;'' mm ta#en down to a point at least as low as the underside of the concrete footings.

The bed of the trench should be provided with a good slope at each end and the trench filled

with co#e, gravel or stone, graded with fines to fill the voids. %n open3jointed land drain may

be laid at the bottom to collect and drain out the sub3soil water. % waterproof coat should be

given outside the structure foundations 8on the external face of the walls9 and continued

through the thic#ness of the walls 8under the walls over the foundation concrete9 and under

the floor. % GA mm layer of waterproof cement concrete can be laid all around. 7ampness can

also be sometimes be reduced by leaving out an air gap around the external wall of the

foundation.

Where sub3soil drainage has been ignored and necessary precautions have not been ta#en,

water will stand about in the foundations, and the warmth of the interior of the building

acting through porous concrete floors will set up suction of moisture which will eventually

give rise to dampness in the floors and walls. Where the sub3soil water is near the ground

surface and can be lowered by underground drainage owing to the flatness of the ground or

any other reasons, the level of the floors of the buildings should be #ept sufficiently high. It is

considered that the height of the plinth should be #ept at least


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- Waterproofing membranes will be environmentally friendly, free from harmful carcinogenic

substances. overnments will have a greater input in the contents, handling and application

of chemicals.

4any people in the waterproofing industry are genuinely excited about the Industry+s future,

the advent of new products, wider fields of application, and a growing recognition of it+s

importance augurs some encouraging signs for the future.

SUMMARY

The awareness and understanding of waterproofing has grown significantly over the last

decade. 4ore and more people are recognising the important role that waterproofing plays in

today+s building industry. ew years bac#, there were no industry associations. Today,

industry bodies such as Waterproofing Industry /ouncil (f %ustralia 8W.I./.%.9 have

emerged as waterproofing grows in prominence as a building material.

Waterproofing is a critical component of any building structure. The four #eys to successful

waterproofing are)

- proper consideration at the design stage

- choosing the right product for the job

- adequate preparation

- the correct application.

The ramifications of failing to waterproof, or waterproofing inadequately can be horrendous.

Documents

Waterproofing in Basements