7/23/2019 Waterproofing in Basements
1/11
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.
7/23/2019 Waterproofing in Basements
2/11
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.
7/23/2019 Waterproofing in Basements
3/11
- 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
7/23/2019 Waterproofing in Basements
4/11
- 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
7/23/2019 Waterproofing in Basements
5/11
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
7/23/2019 Waterproofing in Basements
6/11
(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
7/23/2019 Waterproofing in Basements
7/11
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 $ew /onstruction Waterproofing /ompany, born in
7/23/2019 Waterproofing in Basements
8/11
B$% T&'e (ate)')$$*ng *$) +ase,ents
P)$-ed.)e:
% base3coat in cement mortar
7/23/2019 Waterproofing in Basements
9/11
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)$-ed.)e:6athway of si*e '.;m to '.Bm width is proposed, with compacted impervious material with
specified flooring on the top. The area beyond this pathway is excavated to form a trench
throughout the periphery of the basement. The highest level of the trench is #ept at least
'.
7/23/2019 Waterproofing in Basements
10/11
T1%T41$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
7/23/2019 Waterproofing in Basements
11/11
- 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.