The Best Way to Keep Moisture out of a Basement with Justin Wilson

Demonstrating with a simulated slab, Justin Wilson of Construction Instruction shows the best way to keep moisture out of basements, what issues can arise when building directly above a sand or dirt layer, and the physics behind moisture control.


Basements have transformed from simple storage areas to valuable extra living space that owners can utilize in a variety of ways. From home theaters to home offices, more time and effort is being spent in this area of the home.

With basements being built deeper into the ground, issues with water management and the importance for basement moisture control become greater. Although moisture barriers are installed on the walls, they are often not installed on top of the footing. By installing an underlayment, you can ensure your basement is completely moisture proof and sealed from the elements – if it’s done correctly.

In the video, you’ll see Justin Wilson use DELTA®-FL as his material of choice. It’s a dimpled, heavy-duty, high-density polyethylene (HDPE) membrane that is completely impermeable. DELTA®-FL provides a capillary break and vapor barrier which acts as a magnet, attracting moisture that rises through the concrete. This air space pushes the water and moisture back into the slab, leaving the above flooring dry.

The dimpled membrane also provides a thermal break, making the flooring warmer and more comfortable, completing a well-rounded system to prevent damp basements.

Learn more about basement waterproofing and foundation protection at the DELTA® Academy: