The process of making a surface or a structure element impermeable, so that water does not pass through. It also be designed to prevent the water percolating through a surface under pressure due to high water table and under seepage due to gravity.
SOURCES OF DAMPNESS :- Dampness of building is generally due to one or more of the following causes:
- Faulty design of structure
- Faulty construction or poor workmanship
- use of poor quality material in construction
Problems occurs without waterproofing :-
- Efflorescence of Bricks
- Plaster Crumbling
- Corrosion of metal
- Warping and decay of timber
- Deterioration of floor covering
- Damage to electrical installations and short circuiting
- Blistering,flaking and bleaching of paint.
- Development of termites
- Development of Unhealthy condition for the occupant of the building
Basic terms of waterproofing :-
- Coving or Haunching :- The process of making corner /edges into a smooth curve for the purpose of turning of waterproofing membrane. it can be done for both side horizontal and vertical portion.
- Ponding :- It is the process of stocking water on a given surface to desire depth for the purpose of checking the area of leakage before and after of waterproofing coating.
- Pressure grouting :- when a grout is forced under pressure into opening in concrete and masonry structure to fill the cavities.It is called as pressure grouting
- Caulking strips :- It is a special type of tape fixed at the corner of wet area, sandwiched between the two layer of under tile waterproofing compound to seal any hairline cracks at the corners.
- Positive side and Negative side waterproofing:-The side of an RCC element , over which the water pressure acts directly and the site opposite to the positive side which is not directly exposed to water pressure
TYPES OF WATEWRPROOFING
- Acrylic Waterproofing
- Cementitious Waterproofing
- PU Based Waterproofing
- Epoxy based waterproofing
- Bitumen waterproofing
Procedure to prepare the area of podium slab Step by Step
- Bore Packing;- The inner side of the cut out in the RCC element should be hacked and apply epoxy bonding agent on the side and fill with non- shrinkable compound
- Haunching or coving : Make all the corner/ edges in concave shape with cement mortar.we can also use Caulking strips for wet area
- Pre-Ponding test:- Clean the area and fill it with water for 24 hours and after 24 hours check the area from basement and mark it .
(Note;- After pre-ponding test we can easily find out the area of leakage and prevent with following process like pressure injection grouting , Construction joints treatment,bore packing , fill all the Tie rod hole, potholes size more than 25 mm with Various Construction chemical compound
3. Construction joints and cracks Treatment :- The chances of leakage is more due to construction joint and preparation of construction joint is more important with following procedure
- V- groove should be made along the length of Construction joints, Cracks and weak portion
- GI- nipple should be fixed at suitable area and pressure grouting should be done using approved grout
- The Groove should be filled with SBR mortar
- The Groove should be saturated with water before grouting
4. Patch hole and Tie rod hole should be clean and saturated with water and filled with SBR mortar and do proper curing
5. Surface cleaning :- The surface to be treated must be dry, clean, structural sound, free from oil,grease ,wax,polish,laitance,dust and other barrier material
6. Priming ;- If the quality of concrete slab is good we have no need of priming and primer is required when the surface is more porous and absorbent , or sand cement screed
7. Waterproofing membrane :- Apply 2 coat of waterproofing compound as per Technical data sheet
8. Post Ponding Test :- After the full cure of waterproofing membrane fill the area again with water and check after 48 hours
9. Geotextile sheet : when we do waterproofing in Open area like podium, terrace,planter box etc Before Cement sand screeding Cover the waterproofing membrane with geotextile sheet otherwise Cover with tile ( Covering should be done as per the manufactures only)
9. Protection screed :- The waterproofing membrane should be protected with cement sand screeding and must be in slope