WATER LEAKEGE REMEDIES AND PRECAUTIONS IN RCC STRUCTURE
WATER LEAKEGE REMEDIES AND
PRECAUTIONS IN RCC STRUCTURE
No. TOPICS PAGE NO.
1.1 Water Leakage in RCC Structure
1.2 Meaning of the Term
2 Types of Terracing
2.1 Types of Terracing
3 Slab Leak
3.1 How to Detect a Slab Leak?
4 Leaks From Terrace
4.2 Terrace Precautions
5 How to Control Roof Leaks
5.2 Locate the Leak from Inside
5.3 Control the Damage
5.4 Locate the Leak From Outside
6 How Water Damages a Ceiling
6.2 Supplies and Tools Needed to
Repair a Water Damaged Ceiling
6.3 Stop the Source of the Water
6.4 Dry Above and Below the Water
6.5 The Mold Danger
6.6 Remove the Damaged Ceiling
6.7 Prepare the Surface of the Ceiling
6.8 Cover the Stain on the Ceiling
6.9 Paint the Ceiling
6.10 Apply Texture to the Ceiling
7.1 An introduction to waterproofing
7.2 Chemical waterproofing
7.4 Polymer flexible slurries
7.5 Elastomeric coating/membranes
8 Water leakage in building
8.1 Leakage & dampness in buildings
8.2 Precaution during construction of
9 Water proofing
9.1 What is water proofing?
9.2 Concert water proofing by
9.3 water proofing compound
CHAPTER 1:- INTRODUCTION
1.1:- Meaning of the term:
The term water leakage in the buildings is used to mean the coming out of water from
components like walls and floors of the buildings. It is observed in the building industry that
99% (percent) of water leakage problems are concentrated on the terrace roofs and in the toilets.
The water leakage in the buildings is the most common problem particularly in all types of
buildings such as residential flats, hospitals, offices, school buildings, etc.
1.2:-Reasons and preventive measures for water leakage:
It is necessary to prevent water leakage in the buildings so as to provide healthy and happy
environment. It will also avoid damages to household articles, Costly painting and short
circuiting of electrical wiring. The defects which cause water leakages in the buildings can be
grouped in the following three categories:
(1) Defects due to poor maintenance
(2) Defects in construction
(3) Defects in design.
Each of the above categories of defect will now be briefly des-cribbed.
1.2.1:-Defects due to poor maintenance:
The neglected maintenance along with weathering and aging leads to the water leakage in the
existing buildings. The flowing water is dynamic and rushes through valves, traps, washers, taps
and cocks situated at several places in the building. These things are subjected to constant wear
and tear. They therefore require periodical maintenance. As such, non-repairing attitude proves
detrimental to the safety of the structure. Following are the measures to be taken to minimize
water leakage due to poor maintenance:
• Filling of joints: The joints in the drainage system should be filled with rich
cement mortar. Due to again, the strength of cement mortar deteriorates resulting in
leakages through the cracked joints. The remedy lies in filling such joints, initially with
epoxy mortar or at least at a later stage while repairing the same.
• Improper use of toilets: It is necessary to educate the public for properly
using the toilet system. For instance, in the drainage system of public hospitals, it is
observed that the patients and their near relatives misuse the toilet systems by throwing
bandages, cotton waste, injection bottles, etc. It ultimately leads to the choking of the
• Joints in floor of toilets: The joints in tiles of bath and water closet are
filled with white cement. These joints get loose after continuous use and require
periodical maintenance and sealing with white cement.
• Replacement of taps: The leaking water taps lead to colossal waste of
filtered water and avoidable water leakages in the building. It is therefore necessary to
provide good quality bib cocks initially and go on replacing washers periodically,
whether required or not, as a preventive maintenance measure.
1.2.2:-Defects in construction:
The defects at the construction stage include honeycombing in concrete, use of
defective materials, bad workmanship, etc. The remedial measures to avoid water leakage due to
such defects are as follows:
• Defective concrete: The provision of well designed compacted dense concrete
with proper curing can solve number of leakage problems in a building.
• Door frame joint near toilet: The joint between door frame and flooring
of bath and water closet should be made leak proof by applying epoxy mortar or cement.
• Plumbing: The joints in the plumbing of w.c. seats and nanny traps should be filled
with rich cement mortar and cured for seven days. If curing is not properly done, the rich
cement mortar gets cracked and leads to leakage. If possible, one piece P trap
• Should be used to reduce one joint in the drainage system and it should be fixed before
water-proofing of the W.C. block is started.
1.2.3:-Defects in design:
The defects in planning and design can be avoided in the pre-construction stage by
entrusting the work to Experienced and well trained architect and engineer. Some of the
Measures to avoid water leakage due to faulty planning are as follows:
Design of floor slab: It should be seen that the design of Floor slab and
centering should be such that the local stagnation of water does not occur.
Design of rain water spouts: The rain water spouts of less than 100 mm diameter
should not be used. It is also desirable to provide one spout for every 40 m2 area of terrace.
Fixing of nanny traps: The nanny traps are required for toilets, Kitchen sinks,
washbasins, etc. The niche or pocket of clear size About 300 mm x 300 mm x 150 mm should be
provided to accommodate the nanny traps and their locations should be clearly shown in the
Location of sanitary block: For public buildings like schools, Hospitals,
hostels, colleges, commercial centers, theatres, etc., it is Desirable to detach the sanitary block in
the planning stage only. Such a criteria will help in keeping the building usable even if the
Sanitary block suffers from leakage. It will also avoid the spreading of dampness in the rest of
• The entire sanitary block should be sunk to a sufficient depth to accommodate the items
of Sanitation. As a matter of fact, the engineer should supply a detailed Plumbing
drawing of the sanitary block showing the slope of pipes, Slope of gutters carrying urinal
effluent, washbasin effluent, general Slope of the toilet flooring, etc.
Relief valves: It is necessary to provide break pressure relief Valves at suitable vertical
distance in multi-storied buildings to prevent seepage of water through the plumbing system.
Slope of terrace slab: The minimum slop of 1 in 100 to 1 in 60 should be clearly
shown on the terrace plan. It will help in adjusting the slope in centering with uniform thickness
of roof Slab. The suitable provision of terrace slope would result in smooth Disposal of
• Water tanks:
For overhead R.C.C. water storage tanks, it should be seen that the permissible limits of
stresses relating to Resistance to cracking are not exceeded. The detailed bar bending
Schedule should be supplied by the designer. The bottom slab of Overhead water tank
should be placed one metre above the roof Slab. It will facilitate proper centering during
construction and also for locating and repairing the leakages after construction.
CHEPTER:-2:- TYPES OF TERRACING
2.1:- TYPES OF TERRACINGS
Proper terracing contributes to a great extent to the waterproofing. Junction
arrangement of a terracing with parapets is of utmost importance. Where a terracing is
not embedded inside the parapet wall as per arrangements in annexure-I, alternative
arrangement is possible to make the joint water proof by arrangements shown in
annexure-V. A brief review of the various types of terracing used and precautions to
be taken are given below:-
2.1.1:- BRICK BAT COBA
This involves lying of 80 – l00 mm thick coba concrete on a prepared surface
with graded broken brick aggregate. Concrete can be lime concrete or cement concrete
with water proofing compound. This is useful for giving the surface the required slope
so as to drain out water quickly. Since brick-ballast is hygroscopic, very good
workmanship, mixing of all the ingredients in correct proportion and adequate
compaction by rammers for lime concrete and by vibrators for C.C. is of paramount
The brick bed coba is topped with IPS or with China Mosaic.
China mosaic is usually provided over a Coba surface by broken pieces of ceramic,
China or Mosaic tiles are set over bed of cement mortar (1:3, 15mm thick).
2.1.2:- INDIAN PATENT STONES (IPS)
This surfacing is used either as a surface barrier treatment over a new
surface or at a location where the ingress of water has taken place. A 25 – 40 mm thick
layer of cement concrete 1:1:2 (8 mm to 10 mm size stone aggregate) is laid over a flat
surface, giving it a correct slope before IPs is laid on top of the same. Joints on IPs are
filled with a suitable sealant like bitumen, mastic, etc. Leakage may also take place
through the joints which develop cracks with time. IPs can also be provided over coba
2.1.3:- MUD PHUSKA WITH BRICK TILES
This treatment usually consists of the following:-
a) 100 mm thick (average) mud phuska consisting of puddle clay mixed with
chopped straw (bhusa) 8-10 Kg. /m3 of soil.
b) Mud plaster of paddle clay mixed with chopped straw 30 to 35 mm long.
c) One or two course of brushing (“leaping”) with fine clay and cow dung in
d) One or two layers of bricks tiles laid on a bed
mud mortar and jointed and pointed
in cement mortar 1:3.Some time a coat of hot bitumen @ 1.7 Kg./Sq m.
On a polythene sheet can be laid below the mud phuskalayer.Mudphuska
also gives excellent protection from heat.
2.1.4:- LIME CONCRETE TERRACING
This treatment has been used since time immemorial. This treatment is however most
successful where temperature variation is less since the lime concrete itself crack under wide
Terracing consists of various proportion (which vary with regions) of brick aggregate,
lime surki and sand to make a lime concrete of thickness 75 to 100 mm which is rammed and
subsequently beaten with wooden thappies for three to four days as it slowly
CHEPTER:-3:- SLAB LEAK
3.1:- How to detect a slab leak?
Every homeowner should be aware of the signs that point to a possible slab leak in the
foundation, and make sure proper action is taken to repair the slab leak.
3.1.1:- The following check list is a good tool for detecting
Significant increase in your water or electricity bill: if you notice that your water or
electricity bill suddenly jumps, It may be due to a slab leak.
3.1.2:- Visible wet or damp stains on carpet or flooring:
A slab leak can sometimes reach the flooring, creating noticeable spots or stains.
3.1.3:- Reduced water pressure:
If you notice a decrease in water pressure, it may be caused by a slab leak.
3.1.4:- Stalling of the foundation:
When an actual shifting of the home’s foundation is felt, a slab leak may have occurred.
CHEPTER:-4:- Leaks From Terrace
Most of the terraces are laid with brick-lime jelly and pressed tiles or brickbat coba for
providing nominal slopes on the roof slab to drain off water through the rainwater down-take
This lime concrete over the RCC is meant for gradation and hydration purpose only and not
used as a waterproofing agent. So, the RCC should be protected with waterproofing system.
Since water has a tendency to take the weaker path, the entry of water from the terrace of
even the ninth or 10th floor can be the cause for leaks in the ground floor or any other floor of
that building. Also, leaks may take place through cracks on the top and sides of the parapet walls
leading to entry of water into the building. Improper sealing of the rainwater down take pipes
also leads to water leaks in the walls/slab of the building.
Care should be taken to provide proper slopes on the slab to prevent stagnation of water.
All opened-up tile joints have to be filled with a polymer - modified waterproof mortar and
Damaged tiles have to be replaced with new ones.
Any exposed concealed pipe-electrical/others on the terrace has to be sealed properly to
prevent water seepage through them into the building.
CHEPTER:-5:- How to Control Roof Leaks
Treat a leaking roof as an emergency, because it can wreak havoc in your house in a very
short time. Attend to any signs of a roof leak, such as water entry, stains or mold, immediately to
limit damage. Locate the leak from inside and then take steps to control the damage until you can
have a suitable outside inspection and repair done.
5.2:- Locate the leak from inside:-
1. The first and perhaps most obvious place to look for a roof leak is directly above the leak in a
ceiling or exterior wall. Use a flashlight to inspect the attic floor over the leak while it's raining.
Look for standing water, water stains, mold, wet insulation or other exposed insulation.
2. Examine the underside of the roof for wetness or mold around points of penetration
(plumbing vents, chimneys), wherever different roof planes intersect (valleys) and near dormers.
These symptoms indicate holes in the flashing or faulty flashing installation.
3. A leak away from such locations suggests a problem in the roofing material. Keep in mind
that water may travel sideways before passing through a joint in the roof sheathing, and may
travel in a horizontal joint before falling on the floor or ceiling.
5.3:- Control the damage:-
1. Water can travel on the underside of sheathing or down roof rafters before dropping off in one
or more places. To control where it falls, tack a piece of string into the stream of water and let it
hang into a bucket. The water will tend to follow the string.
2 .Poke or drill a hole in your ceiling to let the water through. This technique prevents the water
from spreading across the top of the ceiling to other areas; it prevents the ceiling from becoming
saturated, eliminating the chance of collapse and often the need for replacement; and it allows
you to collect water from below using the string-and-bucket method.
5.4:- Locate the leak from outside:-
1. Using any measurements or other information you gathered indoors, make your initial
outdoor observations from a ladder and/or using binoculars. Do not walk on a pitched roof
during rain or as long as the roof is wet. A wood roof is particularly treacherous.
2. Look for leaves and other debris slowing the natural downward flow of water, as often
happens in valleys and adjacent to or above any roof penetration or dormer. If there is snow on
the roof, an ice dam may have formed at the roof's lower edge, causing water to back up under
overlapping layers of roofing materials. Remove the obstruction if you can get to it safely.
3. If or when you can safely get close enough, examine metal flashings for corrosion or
open joints where they connect to a chimney or other roof penetration. You can temporarily
patch metal flashings, but replacement is the only permanent solution. Typically, you can replace
cracked or dried-out rubber gaskets on plumbing vents
CHEPTER:-6:- How Water Damages a Ceiling
Water always flows down and always follows the path of least resistance. When water
flows onto a ceiling from above, it looks for the easiest way to keep going down. With drywall,
this is usually where two panels of drywall meet. The water drips through the gaps in the seams.
With plaster, it is usually the place where the water pools up. It saturates the plaster then drips
right through. The ceiling material soaks up the water and changes color. It becomes heavy and
sags. In extreme cases of water damage, huge chunks of the ceiling collapse. Water allowed to
min gle inside your ceiling and walls will grow mold that is very difficult to get rid of once it
starts to grow.
6.2:- Supplies and Tools Needed To Repair Water Damaged
You will need several supplies and tools to repair a water damaged ceiling. You may
have to get some or all of the following items:
• · Ladder
• · Towels
• · Vacuum cleaner
• · Fan
• · Screwdriver
• · Bucket
• · Putty knife
• · Paint Scraper
• · Sandpaper
• · Joint compound
• · "Kilz" primer
• · Tarps
• · Masking tape
• · Plastic sheets
• · Paint
• · Canned ceiling texture
6.3:- Stop the Source of the Water
This is the first thing you should do. It does not make any sense to repair a water
damaged ceiling if more water will come in and damage it again. Find out where the water is
coming from and stop any more from getting in. This could require you to fix a roof, replace a
pipe or threaten a neighbor who is leaking water into your home.
6.4:- Dry Above and Below the Ceiling
Once you stop the water from coming in, mop up as much water as you can as quickly as
you can. Dry everything out with towels, vacuums and fans. Do this both above and below the
ceiling. If water is dripping through that means the ceiling is saturated. The ceiling must either be
dried out or the wet portions removed. If the ceiling plaster or drywall is bulging, stab it with a
knife or a screw driver. Be careful. Water may come pouring out. Place a bucket underneath the
bulge before poking it.
Dry Everything Out Quickly
6.5:- The Mold Danger
Mold grows very well in moist and dark places. If you eliminate the water in the ceiling right
away you may be able to stop the mold from sprouting. If you allow the ceiling to be damp for
several days, mold might start growing and thriving. Once mold gets into the interior passages of
home, it is extremely difficult and costly to get it out. Sometimes homes are completely
condemned because mold has taken over. Do not take this lightly. Dry everything out as quickly
as possible. This may require several days with a fan blowing on it. Once the moisture is gone
and you are convinced the water is not coming back, you can begin repairing the water damaged
6.6:- Remove the Damaged Ceiling
Scrape away any pieces of plaster or drywall that are loose, bulging or peeling away. If it
is moist to the touch, tear it out. If it is flaking or chipping, scrape it with a putty knife or paint
scraper until it is flat. If the ceiling is discolored but otherwise flat and unchanged, you do not
need to scrape it.
Severe Ceiling Damage
6.7:- Prepare the Surface of the Ceiling
Use sandpaper to remove the ridge separating the damaged and undamaged areas of the
ceiling. Make this as smooth as possible. Major holes will require new sheets of drywall or
plaster. Repair small holes by filling them with joint compound. Smooth them level with a putty
knife and allow it to dry. Once it is dry, sand it again to remove any bumps. Do this until it is
smooth to the touch and your fingers can not tell where the patch begins and ends. If the ceiling
is only discolored and has no holes, skip this step and move on to the next step.
6.8:- Cover the Stain on the Ceiling
Buy a can of a primer called "Kilz." It covers any kind of stain so it cannot be seen later. If
you just paint over water damage, it can show through the paint or appear later. Kilz looks like
ordinary white paint but does much more. Apply a coat to the stain area and allow drying. Apply
more coats of Kilz if necessary. Be sure to ventilate the room to prevent the buildup of toxic
6.9:- Paint the Ceiling
. Secure them with masking tape. Before you begin any large scale painting, spread out tarps on
the ground underneath the part of the ceiling where you are painting. Once the layers of Kilz are
dry, paint the ceiling with a color that matches the rest of the ceiling. If the ceiling paint is old
and hard to match, it may be more efficient to paint the entire ceiling in that room. If you are
painting the entire ceiling, cover furniture and the walls with plastic sheets
6.10:-Apply Texture to the Ceiling
if the ceiling has texture; spray some canned ceiling texture on the damaged area. Wait for it to
dry and see if it matches the rest of the ceiling. Add another coat if more is required. The water
damaged ceiling is now repaired.
CHEPTER:-7:- Waterproofing system
7.1:- An Introduction To Waterproofing Systems:-
Many homeowners find it necessary to invest in waterproofing systems for their
homes, especially if the house has a basement or a cellar. In modern home developments, it is
Often required by state or local regulations to have waterproofing systems installed before the
completion of the home, because without a proper installation of such a system your house is at
risk for water damage or the growth of black mold in prone areas. There are also other factors
that you will have to consider when implementing waterproofing systems such as the landscape,
climate, terrain of the area and the weather.
The waterproofing systems are necessary because normally basements leak for a multitude
of reasons. Water can build up because cracks in the walls or the floor, improperly installed or no
footer tiles, pressure build up from the floor or walls, leaks from sweating basement pipes and
leaks from basement windows and many other reasons. The mold is a dead giveaway that your
basement has leakage or condensation problems. In case you have problems with the black mold
then it is imperative that you seek a professional installer for your waterproofing system.
Another important reason for installing waterproofing systems is the roof leakage. One of
the most popular methods that has been a top choice in roof maintenance for more than 35 years
are the spray polyurethane waterproofing systems. The spray polyurethane waterproof has a lot
of advantages to offer when it comes to protection systems, such as waterproofing/leak
prevention and insulation value, better compressive strength, lightweight and the durable and
long lasting effects, just to name a few.
Buildings incorporate latest scientific methods to ensure perfection in appearance while
waterproofing is done by methods that are centuries or possibly millennia-old. Frenetic speed,
non-availability of quality Construction materials and lack of sincere labor are reasons for poor
structures coming-up of late, says A. C. RAVI RANGASWAMI
Laying of tiles on a waterproofed terrace
CONSIDER a house that you are visiting. It is less than a year old. Its façade is
impressive. Its design is ornate and available space has been skillfully exploited. You admire the
beautiful and apt colors used too. But as you look up, at the ceiling, you find a damp patch in a
corner, spoiling the whole appearance of the room. No expense has been spared to make the
house look grand but have the architect and builder been remiss in bestowing attention on the
durability of the structure? The small patch in the ceiling does not mean that water has leaked
through that spot alone. It means rather, that water spreading over a longer area and through
various channels behind and below the surface, has, for the present, been able to escape to the
surface at that point only. Obviously, stop-gap repair work to clear that blemish will not help,
for, over a period of time, perhaps after the very next shower, the moisture will find other portals
of entry to the surface of the walls and ceilings.
What then, is the source of this evil? Why is this leakage of water, even in new buildings,
a ubiquitous problem in Chennai? The answer is that waterproofing of buildings receives scant,
if any, attention at the time of construction. While other aspects of the building incorporate latest
scientific methods to ensure perfection in appearance and quality, waterproofing is done
following methods that are centuries, possibly millennia old.
In those days, construction was done at a leisurely pace. Curing of concrete/mortar was
given great importance. Curing is one of the most important factors determining the strength and
water tightness of concrete. But nowadays, we witness huge buildings cropping up within a few
The main reason for waterproofing being accorded step-motherly treatment is lack of
awareness of its long-term benefits.
Waterproofing is an integral part of the construction activity and its critical role must be
appreciated. We fail to realize that all the money we spend on aesthetics will go down the drain
if we do not ensure that the house is waterproofed. This is confirmed by the absence of
waterproofing details in the advertisements released by construction companies that provide all
other details, which are physically visible.
Water seepage is just not an inconvenience but also damages your concrete, causing
corrosion of steel reinforcement. Durability of the finished structure relates to concrete's ability
to preserve the alkaline environment around the reinforcement during its service life and to
maintain its structural capacity. The protection of the reinforcement is lost if harmful substances
like chlorides or carbon-dioxide and other toxic gases like nitrogen oxide and sulphuric oxides
penetrate the cover layer along with moisture and oxygen causing corrosion of the re-bars.
Slope-making (with concrete) towards down take pipes
7.2:- Chemical Waterproofing:-
Chemical admixtures are ingredients in the form of powder or liquid, added to the concrete
matrix during mixing. Admixtures are actually no substitute to waterproofing of buildings but
definitely provide many beneficial effects.
The advent of coating membranes followed admixtures but unfortunately they are not found
suitable for Indian conditions. In surface coating, the pores and capillaries are blocked,
hampering the natural breathing of the building. The impermeable surface coating allows water
to build up behind the surface coating with the risk of disruption to the coating and possibility of
damage. In fact, trapped water would be moving behind surface coating and wherever it finds
weaker segments, it would come out resulting in cracks and blisters on the surface.
Bitumen or asphalt is widely used as a coating. Bitumen, on attaining high temperature,
particularly in summer, undergoes photo-oxidation, initiated by UV radiation. This results in the
formation of cancer-causing and toxic polyaromatic compounds including Benzopyrene (B) (a
harmful toxic constituent as in cigarette smoke) which have led to the banning of bitumen in
7.4:- Polymer Flexible Slurries/Membranes:-
The proportion of polymer in these is at least 40 per cent, expressed in terms of cement. As a
result, the cement no longer forms a firm framework. In fact, the polymer bonds the mixture of
sand and cement to yield a soft and flexible structure.
7.5:- Elastomeric Coatings/Membranes:-
The entry of recent generation of elastomeric coatings/membranes has revolutionized the
waterproofing industry. These elastomers are special class of materials that are flexible and
breathable, with high elongation and weather ability and crack bridging membranes.
Solvent-based impregnates have several problems — Toxicity, hazardous, environmental
pollution, odor and so on. In various countries, there is now legislation in place limiting the use
of organic solvents in the coating and imp regnant industries.
In the West, experts recommend solvent-free aqueous silicone ester emulsion for
waterproofing of external brick walls and exteriors without leaving any patch. At present, this
product is manufactured as well as imported into our country.
A majority of the products available in India are based on the coating technique, while the
latest impregnation technique is offered by only a few companies. Some of the major players in
the waterproofing industry are Forsook, Rife, McBauchemie, Pixilate, STP, Don, Xpedx, Tech-
Dry etc. As far as Chennai is concerned, the coating technique is preferred since it is a one-step
treatment and less time-consuming.
The impregnation technique, which is becoming popular worldwide, is a multi-step
treatment and several civil engineering professionals are really impressed by the results of this
technique and recommend it to their clients. But, it must be borne in mind that application skills
play a very important role in the success of any waterproofing system. It calls for considerable
expertise and specialized labor.
Application of polymer modified coating helps to avoid water
CHEPTER:-8 WATLEAKAGE IN BUILDING
8.1:-LEAKAGE & DAMPNESS IN BUILDINGS
Leakage in building, especially roofs has been a cause of concern on the Indian
building. There is hardly any railway building, which does not show signs of leakage.
Apart from inadequate water-proofing, which has been dealt with in detail in these
papers, our failure to observe certain precautions at the time of construction of these
buildings largely results in leaky roofs.
8.2:-PRECAUTIONS DURING CONSTRUCTION OF
Some of the essential precautions to be taken at the time of construction are as
i) Every building plan, whether for new building OR for addition/alteration to new
building, must give details of terracing to be provided , water proofing system for roof
with details of joint with parapet wall, sunken `floor and down water pipes in scale not
smaller than 1:20
ii) Specifications laid down by the manufacturers of
the water proofing products should be followed scrupulously to ensure that no air
bubbles are left between the under lying surface and the water proofing layer. Adequate
overlaps should water proofing layers, including cover up to the parapet wall. There are
a large number of relevant Indian Standards Codes of practice available. Their
provisions regarding material & execution may be followed.
iii) Drainage slope of the roof is one of the most important factors. For the guidance of the
field Staff, each building plan must also incorporate a roof plan, showing the position
of drainage Pipes and direction and extent of slope on the roof. Drainage slope should
not be flatter than 1 in 80 and should preferably be 1 in 40. There should be no
undulations in the roof surface, which may result in accumulation of rain water. At
the time of construction, the roof levels should be personally recorded by the
Inspector of Works and 100% check exercised by the Assistant Engineer. Extra care
is necessary for construction of goals, coping and joints.
iv) At the extension joints in buildings, water proofing has to be strengthened by inserting
a PVC Or a copper plate to prevent water from seeping. These joints should also be
plugged by a good sealant. Polysulphide based flexible sealants have good adhesion
to concrete surfaces and can be compressed or stretched up to 50% of the width of the
joints and are good material for sealing of expansion joints. Depth of the expansion
joints above the copper/PVC plate should normally be kept half of the joint width and
should not exceed 20 mm.
v) Special precautions should be taken for sealing of area around the water spouts to make
them water proof.
CHEPTER:- 9 WATER PROOFING
9.1:- What is Water Proofing?
Ø Waterproof or water-resistant:- describes objects relatively unaffected
by water or resisting the ingress of water under specified conditions. Such items may be
used in wet environments or under water to specified depths.
Ø In construction, a building or structure is waterproofed with the use of membranes and
coatings to protect contents underneath or within as well as protecting structural integrity.
Ø The waterproofing of the building envelope in construction specifications is listed under
'07 - Thermal and Moisture Protection' within Master Format 2004, by the Construction
Specifications Institute, and includes roofing material as well as waterproofing materials.
Ø Waterproofing is used in reference to building structures (basements, decks, wet areas,
Ø Waterproofing should not be confused with roofing, as roofing cannot necessarily
withstand hydrostatic head, and waterproofing can.
9.2: CONCRETE WATER PROOFIN CRYSTALIZATION
These products comprise mineral based hydraulically setting products, which when
applied to concrete as a cementations slurry react with concrete to form a crystalline structure
deep within the capillary and pore structures, blocking voids and producing a water proofing
effect. Cement and sand used in the product are used as a carrying agent for the chemicals.
The active components in slurry react with the by – products of cement hydrations and give
rise to insoluble crystals. The system becomes permanent, integral part of the concrete itself..
There is no other preparation of concrete needed beyond cleaning the surface. The product
comes in different names and the products available and their manufacturers are given at
This treatment may be useful for dampness due to capillary action of poorly executed plinth
damp course. For better results however downwardly inclined holes are to be bored in the
masonry where the “Semitist VK” of MC Biochemical can be grouted. This will diffuse into the
masonry and give plinth protection from dampness.
Sketches showing some different types of water proofing arrangements for existing and
new constructions are enclosed at annexure 1-5.
Addresses of some of the manufacturers of various water proofing materials are also given at
9.3:- Water Proofing Compound
It is used for water proofing of any surface from which water is leaking or as pre
It is composed of mainly two things one is the liquid form compound and a sheet of
finely fibers of plastic.
• How to use:-
• First of clean up the surface where proofing is to be applied.
• Apply a single layer of the mixture.
• Spread the fiber sheet over the entire area.
• Now again apply another layer of the mixture.
• And let it to dry.
• Compound: 60-70rs per liter
• Fiber sheet: 60rs for 1.2*1 sq.
Isolation joints have one very simple purpose—they completely isolate the slab from something
else. That something else can be a wall or a column or a drain pipe. Here are a few things to
consider with isolation joints:
Even wooden columns should be isolated from the slab.
Walls and columns, which are on their own footings that are deeper than the slab
subgrade, are not going to move the same way a slab does as it shrinks or expands from
drying or temperature changes or as the subgrade compresses a little.
Very long unjointed sections can expand enough from the hot sun to cause blowups, but
this is rare.
If slabs are connected to walls or columns or pipes, as they contract or settle there will be
restraint, which usually cracks the slab—although it could also damage pipes (standpipes
or floor drains).
Expansion joints are virtually never needed with interior slabs, because the concrete
doesn't expand that much—it never gets that hot.
Expansion joints in concrete pavement are also seldom needed, since the contraction
joints open enough (from drying shrinkage) to account for temperature expansion. The
exception might be where a pavement or parking lot are next to a bridge or building—
then we simply use a slightly wider isolation joint (maybe ¾ inch instead of ½ inch).
Blowups, from expansion of concrete due to hot weather and sun, are more commonly
caused by contraction joints that are not sealed and that then fill up with noncompressible
materials (rocks, dirt). They can also be due to very long unjointed sections.
Isolation joints are formed by placing preformed joint material next to the column or wall
or standpipe prior to pouring the slab. Isolation joint material is typically asphalt-
impregnated fiberboard, although plastic, cork, rubber, and neoprene are also available.
Isolation joint material should go all the way through the slab, starting at the subbase, but
should not extend above the top.
For a cleaner looking isolation joint, the top part of the preformed filler can be cut off and
the space filled with elastomeric sealant. Some proprietary joints come with removable
caps to form this sealant reservoir.
Joint materials range from inexpensive asphalt-impregnated fiberboard to cork to closed
cell neoprene. Cork can expand and contract with the joint, does not extrude, and seals
out water. Scott Whitelam with APS Cork says that the required performance is what
determines the choice of joint materials. How much motion is expected, exposure to salts
or chemicals, and the value of the structure would all come into play—and of course the
At columns, contraction joints should approach from all four directions ending at the isolation
joint, which should have a circular or a diamond shaped configuration around the column. For an
I-beam type steel column, a pinwheel configuration can work. Always place the slab concrete
first and do not install the isolation joint material and fill around the column until the column is
carrying its full dead load.
Polyethylene foam isolation joint material comes in various colors. C2 Products