How to Waterproof Concrete Foundations

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Waterproofing a concrete foundation is a job best left to professionals, or to be attempted only by the most confident and accomplished do-it-yourselfer.

If you are in this second category, this guide can help you understand what you are up against and make the decision to do it or to hire the work out to a company like Mar-Flex.

Waterproofing or Dampproofing?

First you must understand whether the work you are doing is waterproofing or damp proofing.

  • Will there be a great deal of exterior  ground pressure on the outside of the foundation and/or is the foundation submerged below ground?
  • Is the space on the interior side of the wall to be used, either for storage or habitation / work?

If the answers to these questions are “yes”, then you are waterproofing, and your work is more rigorous than merely dampproofing.

Waterproofing Process

First, full expose as much of the external foundation as you can. This is easiest with new construction, of course, but even with an established building, care must be taken to reach the whole concrete side of the structure.

Then, patch any holes, chips or cracks with a commercial-grade mastic or cement patching mix.

Once that dries, clear the surface of any dirt or debris.

When the surface is dry and clean, treat it fully with a commercial grade waterproofing sealant. Be sure to wear appropriate protection for this process, including an appropriate mask to prevent breathing fumes.

When this surface dries a final time, apply an external waterproofing barrier. This final barrier might look like fabric, but it should be a product similar to GeoMat or ShockWave. These specially-made barriers are constructed to direct water away from the foundation of your home.

Once this is properly installed and inspected, begin the careful backfill of rock and soil around your home. Fill until you reach the level of your rainwater management system.

At the appropriate level, install a below-ground drainage system. This can be as simple as a french drain that will help capture water below the surface and direct it into your rainwater system and safely away from your home.

Enjoying your dry space !

Waterproofing the exterior of your home can last a lifetime. In fact, some Mar-flex products have guarantees that stretch as long as a lifetime when verified as being properly installed by a Mar-flex approved applicator on a residential application.