What Is The Difference Between Damp Proofing And Waterproofing?

Damp proofing is performed to keep out the soil moisture or dampness from the building structure, while waterproofing is applied to keep moisture and liquid water away and from damaging the building structure.

 The American Concrete Institute (ACI 515.1) and the International Residential Code (IRC) mention waterproofing and damp proofing as follows.

Bitumen Waterproofing
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Choosing between damp proofing or waterproofing is merely dependent on the moisture conditions of the site, the type of building, and environmental concerns. 

We will discuss in detail damp proofing and waterproofing procedures conducted for buildings and their best applications.

Damp Proofing and Waterproofing for Buildings

As per the International Residential Code (IRC), in Section R406:

Any concrete or masonry foundation walls that retain earth and enclose interior spaces and floors below grade shall be damp-proofed from the top of the footing to the finished grade. While waterproofing is required in areas where there is a high water table or other severe soil-water conditions are known to exist.

As per ACI 515.1:

Waterproofing treatment of a surface helps to prevent the passage of water from one side to another under normal or hydrostatic pressure. Damp proofing treatment prevents the water passage from one side to another by capillary action.

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How is Damp Proofing Performed?

• Damp proofing is performed using a mixture of traditional tar or unmodified asphalt.
• It is applied mainly on a concrete surface constructed over the ground to stop the transference or wicking of ground moisture through the concrete through capillary action.
• Damp proofing is a basic technique used to slow water penetration and hence does not have the ability to seal larger cracks, large bug holes, surface protrusion, and potential damage caused due to backfilling or etc.
• If only damp proofing is performed, it is essential to have a correctly installed foundation drain at the footing and check there is no presence of hydrostatic pressure to drive water infiltration.

How is Water Proofing Performed?

• Waterproofing a concrete surface stops water infiltration and also helps to bridge the cracks that arise due to the elastic, flexible nature and thickness of the waterproofing coating.
• Waterproofing membranes must stop water vapor, stop water under hydrostatic pressure, and must be able to span a crack in the treated concrete surface.
• Waterproofing treatment is essential in areas where the site is prone to significant rain and high water table. 
• It is a good choice in areas with clay soils as clay soils absorb and holds more water.

Difference Between Damp Proofing and Waterproofing Materials

Aspect	Damp Proofing	Waterproofing
Purpose	Prevents moisture (dampness) from rising through capillary action.	Prevents water under pressure from entering the structure.
Exposure	For non-pressurized moisture (e.g., rising damp from soil).	For pressurized water (e.g., rain, groundwater, leaks).
Common Materials	- Rich cement concrete (1:1.5:3) - Cement mortar (1:2) with waterproofing admixtures - Bituminous coatings - Polythene sheets (0.25 mm min as per IS 2508) - Mastic asphalt	- Bitumen membranes (APP, SBS) - PVC or HDPE membranes - Crystalline waterproofing compounds - Liquid waterproofing membranes (polyurethane, acrylic) - Epoxy coatings - Cementitious waterproofing slurries
Thickness	2 to 2.5 cm (as per Indian standards like IS 3067:1988)	Varies widely (1.5 mm to several layers depending on the application and pressure conditions)
Application Areas	Plinth level, wall base, floors above ground	Basements, roofs, water tanks, bathrooms, terraces, tunnels
Flexibility	Less flexible; mainly rigid materials	Highly flexible and elastic to handle cracks and movement

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