Difference between Waterproofing and Damp proofing
Waterproofing and damp proofing are both closely related methods of protection of structure against moisture, mold formation and seepage of water. Yet are different in many ways including their purpose, methods, materials used and protection provided.
Let’s get to understand what these two actually mean.
What is waterproofing?
Waterproofing is used to prevent all moisture including groundwater, and rainwater from permeating into a structure. It is done in the basement, wet areas, roofs etc. to stop leakage and moisture buildup.
So what is damp proofing?
The main purpose of damp proofing is to stop the wicking or transfer of moisture through the masonry and concrete by simply blocking its entry. When it is in case of high ground water table or rain season when soil is always damp, a building’s foundation is likely to absorb moisture which rises through capillary action causing dampness on walls. Damp proofing acts as a barrier and prevents rising damp and condensation.
Both waterproofing and damp proofing are essential during the construction stage itself. Paying attention to the right method is important to prevent aesthetic and property damage. However, they need to be redone if the structure has been damaged and there is seepage of water causing mold formation on walls.
Waterproofing is essential to prevent damage to the building and ensure it has a long life. It not only protects the building and its interiors from damage but also safeguards the people by ensuring the structure remains strong and does not deteriorate and collapse.
Damp proofing is essential for ensuring the structure stays strong and withstands against absorbing the moisture in adverse weather and soil conditions. It also helps create a good and healthy living environment for the inhabitants by blocking out dampness which can cause respiratory issues.
Some commonly used methods of waterproofing are:
- Cement-based waterproofing
This is the easiest and most widely used method for domestic wet areas like bathrooms and toilets as well as structures like water tanks, planters, small roofs and balconies etc.
- Liquid waterproofing membrane
This is a thin coating, usually consisting of one or two components, applied by spray, roller or trowel. It offers more flexibility than cement-based waterproofing and hence is used more widely.
Image source: Archiproducts
- Bituminous coating waterproofing
Also called asphalt or Tar based coating, it is an economical, basic protective coating with limited life. It is not suitable for exposure to sunlight for a long time.
- Bitumen membrane waterproofing
Multi-layer Tar sheets and APP membrane rolls are popular in this category. It can be torch-on or self-adhesive bituminous waterproofing. Certain resins and oils may be added to the self-adhesive compounds in order to improve the adhesion properties. As the adhesion properties of the membrane decrease over time, this self-adhesive membrane has a low shelf life.
Some commonly used methods of dampproofing are:
- Damp proof course (DPC)
DPC is a barrier designed to prevent moisture from rising by capillary action into the walls at plinth or upper floor levels. The conventional DPC is a thick layer of plain cement concrete in M15 to M20 grade, coated with flexible coating based on polymer or bitumen. This method is quite time-consuming and skilled workmanship is key for performance.
- Shot Concrete (Guniting)
Guniting on walls consists of forming an impermeable cementitious layer of enriched cement mortar in the ratio of 1:3 or 1:4 on masonry or concrete surface to act as a moisture barrier. The mortar upon drying becomes very hard and strong making the surface water-impermeable.
- Cavity walls
Cavity walls are 2 masonry skins separated by air space forming a cavity in the middle. The formation of a cavity prevents the transmission of moisture from the outer to the inner wall.
Image source: Civil Bull
- Silicone damp course
Also known as wall injection damp proofing which is trial and error based. It involves drilling a series of holes in the wall and injecting the silicone-based dampproof liquid. The injected fluid diffuses rapidly before curing to form a DPC barrier for the affected area.
- Integral dampproofing
This involves mixing water permeability reducing admixtures to concrete or cement mortar of the building during construction. The purpose of this is to fill pores and voids in the concrete and mortars to ensure it is damp-proof.
- Damp Proof Membrane
Bituminous or Polyethylene based membrane rolls are used as a damp proofing membrane. These are loosely placed, many times unbonded, dimensionally unstable and has limited life under adverse conditions.
- Pressure grouting
This is a trial and error method helps to seal major cracks in concrete using cementitious or resin grouts with pressure.
The technological advancement in the DPC arena is DampX which is designed to provide a permanent solution against rising damp in walls from plinth or floor level, into the structure. This method uses a robust and highly flexible elastomeric membrane to create a physical barrier under the walls which stops moisture from rising through capillary action. It becomes monolithic with structure, easy and quick to install as well as has the longest life within its category.
Most buildings have been constructed using traditional waterproofing and damp proofing techniques but with advancements in technology and increased structural demands, new age methods have evolved that provide long life, ease of application, better protection to the structure and ultimately a good indoor air quality to inhabitants.