Damp-proofing is a coating, usually asphalt-based, that is either sprayed on or hand applied 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 form ties and the potential for damage by coarse or careless back-fill. But with proper surface drainage, correctly installed foundation drains at the footing, and the absence of hydro-static pressure to drive water infiltration, damp-proofing can supply adequate and long-lasting protection for many crawl spaces and basements.

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Waterproofing a foundation requires the same care as damp-proofing in regard to surface treatment and drain pipe, but is much more exacting in the treatment of the wall itself. Obviously, 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.