Damp Proofing treatment.

1. DAMP-PROOFING TREATMENT FOR FLAT ROOF
Submitted by:
Diviyanshi Aggarwal
Atul Kishor

2. Contents:
• Introduction to dampness.
• Causes of dampness in roofs.
• Technique used for dam proofing.

3. Introduction
• Dampness in building may occur due to bad design, fault in
construction and use of poor quality of materials.
• Dampness affect the building as well as the hygienic condition
inside it.
• The process to prevent this dampness is generally called
‘water-proofing’ .
• Treatment to check and repair this dampness is very important
task in construction of a building.
• Flat roofs require relatively heavier and costlier water-proofing
treatment as compared with pitched or sloped roofs.

4. Causes of Dampness in roofs
• Poor quality of construction material.
• Bad design.
• Fault in construction.
• Rain water falling on the external walls, parapets also causes dampness.
• Rain water can also penetrates the roof if the roof is of low quality .
• Inadequate roof slopes or defective junction between roof slab and
parapet walls can cause dampness.
• Leakage through downpipes can causes dampness.
Inadequate roof slope
Leakage through pipes

5. Techniques for treatment of dampness in flat roof
• Grading of Lime concrete.
• Grading of lime concrete with tiles.
• Grading of mud phuska with tiles.
• Screed concreting.
• Tar-felting.
• EPDM.

6. Property of material use for Damp-proofing.
• It should be impervious.
• It should be strong and durable, capable of withstanding loads.
• It should be dimensionally stable.
• It should be free from deliquescent salt like sulphate chlorides and
nitrates.
• The material should be reasonably cheap.
• The material should be such that it is possible to carry out leak proof joint
work.

7. Grading of Lime concrete.
• This method id adopted in hot and humid region of India.
• This method include laying of lime concrete grading over the
roof slab.
• Material used in this method:
a) Lime concrete.
b) Bitumen solution (hot).
c) Bitumen sheet.

8. Process of laying lime concrete:
• Lime concrete of 10 cm thickness(average) is laid over the roof
slab directly.
• The slope is provided to the cement layer for proper drainage.
• Now a priming coat of hot bitumen solution is applied over
lime concrete.
• At last bitumen sheets is laid over the primed surface.
• Sometimes bitumen sheets are not considered in some parts
of country.

9. Water-proofing treatment of flat roof using Lime concrete.

10. Grading of Lime concrete with tiles
• Recommended in hot and humid regions of India.
• In this case roof is used for sleeping or other purposes.
• The grading must be strong enough to withstand the load because of
traffic of the user.
• Roof are make strong by using by covering with two courses of brick tiles
set in cement mortar.
• This process is commonly used in southern region of India.
• Materials used:
a) Bitumen(hot)
b) Coarse sand
c) Lime concrete
d) Flat brick tiles.

11. Operations involved in lime concrete with tiles:
• Firstly, the top of roof slab is painted uniformly by hot bitumen at the roof
surface.
• Coarse sand is applied immediately at the roof surface, the bitumen must
be hot.
• Then the lime concrete is laid over it with the thickness of 10cm. The slope
is given in this concrete layer.
• Finally, two courses of flat brick tiles (with breaking joints) are laid over the
compacted later of lime concrete in cement mortar (ratio: 1:3 ).
• Thickness of each course of tile varies from 13 to 20 mm.

12. Grading of Lime concrete with tiles
Water proofing treatment of flat roof using lime concrete with tiles.

13. Grading of mud phuska with tiles.
• Recommended for hot and arid regions.
• It is commonly adopted in Delhi, Punjab, Rajasthan and U.P. and other
regions where the rainfall does not exceed 1000 mm.
• Materials used in this technique:
a) Bitumen (hot)
b) Coarse sand
c) Mud phuska
d) Brick tiles
e) Mud gobri mortar 3:1 (3 mud:1 cowdung).

14. Steps involved in this process:
• Firstly, the top of roof slab is painted uniformly with layer of hot bitumen at
the roof surface.
• Then the coarse sand is applied immediately when the bitumen is hot at the
roof surface.
• 10 cm thick mud phuska layer is applied at the bhusa being given to this layer.
• The slope for proper drainage of roof being given to this layer.
• A part of the slope required for the roof drainage may be given in the roof slab
itself.
• Then the mud phuska is plastered with a 13 mm. thick coat of mud gobri
mortar 3:1.
• Lastly, the tile brick is laid on plastered surface and the joints are grounted
with cement mortar 1:3.

15. Water-proofing treatment of flat roof using mud phuska with tiles

16. Screed Concreting.
• This method is adopted in hot and humid region in India.
• In this process a proper slope is provided to the roof.
• Materials used in this process
a) Sand.
b) Cement.
c) Admixture.

17. Method of applying this treatment:
• Firstly, the screed cement (mixture of sand, cement,
admixture) is laid over roof slab directly which is 100 mm for
new roof and 20 mm for renovated roof.
• Then the slope is given to the roof.
• After that sand/cement topping of 10-20 mm is given to the
cement to protect the layer.
• At last the layer is dried for two days.

18. 1) The screed mixture is prepared
2) The mixture is laid over the roof slab
3) Proper slope is given to the roof
4) sand/cement topping of 10-20 mm is done over the screed cement.

19. Detail of roof slab, displaying topping
Detail of different layers of roof..

20. Advantages & Disadvantages
• Usage of cement lead to
better water-proofing
system.
• It gives proper slope to the
roof.
• It is durable & permanent.
• It repairs the other voids or
cracks which is already
present at the roof slab.
• In this process sometimes
general cracks are
developed.
• It provide extra load to the
whole structure.
• It lead to level problem.
• Sometimes it creates ugly
patches to the ceiling.

21. Tar-Felting
• Tar-felting is a process by which a wall or a roof of the house is wrapped or coated
with certain types of material such as “ BITUMEN FELT” or plaster for insulation
and water protection.
• Generally used in hot area.
• Materials used in this process:
a) Bitumen mastic (mastic asphalt)
b) Bitumen felt
c) APP and SBS (are the modified bitumen= bitumen + plastic).

22. Method used in Tar-Felting:
• Firstly, brooming and cleaning of roof is done and the dust are
removed.
• Then the layer hot bitumen felt is provided to the roof slab
which covers the damage (or crack).
• Lastly, the bitumen sheet is laid over hot felt.
• The sheet get sticked to the roof slab and work as
waterproofing agent.

23. 1) Firstly the hot bitumen felt layer is applied on roof slab.
2) secondly, the bitumen sheet is laid over the hot fluid.
3) lastly, the edges are folded to a certain height.

24. Advantages & Disadvantages
• It protects the roof deck from
rain.
• It provides an extra weather
barrier in case of blow offs or
water penetration through the
roofing or flashings.
• It protects the roofing from any
resins that bleed out of the
sheathing.
• It have high tolerance for UV rays
• It requires less investment.
• Bitumen is mostly produced
from crude oil and is not regarded as
a sustainable building product
• Bitumen is combustible
• Exposure to extreme heat and UV
radiation drastically decreases the
lifespan
• The fumes that are produced during
hot application of asphalt or tar can
cause dermal and respiratory
problems

25. ETHYLENE PROPYLENE DIENE MONOMER
• EPDM (ethylene propylene diene monomer) is an extremely durable synthetic
rubber roofing layer.
• Its two primary ingredients , ethylene and propylene, are derived from oil and
natural gas.
• This method is adopted in heat and heavy rainfall area.
• Materials used in this technique:
a) EPDM Polymer
b) Carbon Black
c) paraffinic oils as softeners and
d) fillers, activators, crosslinking systems etc.

26. Method used in EPDM
• Firstly, the roof slab is cleaned and dried and no debris or crack should be present.
• Then membrane is unfolded and laid into position. The membrane is left for 30
minutes to remove wrinkles.
• The membrane is then cleaned with recommended cleaner. The membrane are
made to be in proper position and wrinkles are removed properly before applying
adhesive.
• Adhesive is applied to exposed deck and back of the membrane. The adhesive is
left until it get dried.
• The adhesive-coated membrane is rolled from exposed area. The membrane is
pushed with roll broom to remove all the wrinkles.
• The process of rolling continued until the membrane is secured.