Waterproofing vs Dampproofing

Waterproofing refers to techniques or materials used to help prevent water from penetrating the basement of a house or a building. Waterproofing a basement that is below ground level involves the application of materials and sealants and the installation of drains and possibly a sump pump to collect, remove, or redirect water away from the basement. There is a definite difference between damp-proofing and waterproofing.

Installing weeping tile (2)

What is Damp-proofing?

Damp-proofing is intended to keep out soil moisture while waterproofing keeps out both moisture and liquid water. Buildings have been damp proofed for years, a practice that used to be mistakenly referred to as waterproofing.

Damp-proofing involves a coating, usually asphalt-based, that is either sprayed on or applied by hand to the outside of the wall. Though less frequently recommended in modern residential construction, it is still an acceptable form of treatment in many situations. The drawbacks include an inability to seal larger cracks or holes left by concrete form ties (used to prevent concrete forms from spreading as a result of fluid pressure of freshly placed, unhardened concrete) and the likely possibility of damage cause by sloppy backfill. Damp-proofing will only retard moisture; it cannot stop a large volume of water resting against the foundation

But with proper surface drainage, correctly installed foundation drains at the footing, and the absence of hydrostatic pressure to drive water penetration, damp-proofing can supply adequate and long-term protection for many crawl spaces and basements.

Application of Delta MS Membrane (4)

What is Waterproofing?

Waterproofing a foundation is similar to the damp-proofing process in relation to surface treatment and drain pipe, but is much more through in the treatment of the wall itself. It is able to expand and bridge cracks in the foundation, withstand water under hydrostatic pressure and also stop water vapor from entering a basement.

The waterproofing process involves: excavating the foundation, repair any damage to foundation by parging, adding a footing level (where the foundation wall meets the footing), applying a dimpled waterproofing membrane, installing new weeping tiles and backfilling foundation.

Exterior waterproofing and drainage is by far the best protection for a basement. It is used almost exclusively when houses are being built. However, in retrofit (re-doing other systems that failed) situations, older homes with established landscaping, connected utilities, air conditioners, patios, decks, additions, garages, etc., exterior waterproofing can be at best impractical. However, if there is any doubt about whether or not damp-proofing will do the job, it’s best to spend the extra time and money to waterproof, particularly for habitable space.