How to Eliminate Moisture Behind Your Basement Vapor Barrier

basement floor
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What You'll Need
Vapor barrier paint
General paint
Vapor barrier sheets

Basement vapor barrier sheets and paints ensure that moisture does not penetrate the walls and ceiling of your basement; however, water vapor will sometimes become trapped behind the barrier, creating a layer of moisture under the floor.

Moisture can then slip through small air holes in the barrier and penetrate the home. There are a few solutions that the homeowner can try to ensure that moisture remains behind your vapor barrier. One solution is to use a different product to prevent moisture from building up, while another is to install some insulation in order to reduce the possibility of moisture building up in the first place.

A Coat of Paint

The best method of preventing moisture from becoming trapped under a plastic sheet is not to have the sheet in the first place. Instead, consider installing basement vapor barrier paint.

Rather than having sheets, which will never be 100% watertight, applying paint means that you can significantly reduce the likelihood of air holes. This liquid is applied usually as a prime to the bare boards of the basement. You avoid adding a layer of mortar underneath the plastic. Apply the paint in a steady, even stroke, avoiding air bubbles and ensuring that all parts of the basement are covered.

Another Coat

Apply a general coat of paint using the same paintbrush to protect your barrier paint and ensure that your basement has an attractive color scheme. Leave the paints to dry completely before using the basement.

Raise the Barrier

Another solution to the problem of moisture penetrating vapor barriers is to lift the sheeting from the floor by constructing a timber frame over the concrete floor and installing the sheeting on top of the timber frame.

Doing so will provide a layer of insulation by trapping air between the concrete and the sheeting. Place your timber lengths into box frames, which should be no larger than the width of your vapor barrier sheets.

Nail your sheets to the frame, taking care to ensure that the barrier is flush with the wood frame. Continue throughout the basement. Finish by adding a layer of caulk, then installing boards or flooring above the sheet.


Insulation is another good idea for those who are able to manage it. The use of insulating foam will keep moisture away from the walls. Use a waterproof material that can dry quickly to cover the bases of the wall and pipe/ductwork.

Take care not to cover hot water pipes, as they can overheat. A layer of insulation between the sheeting and the floor of the basement will also keep out moisture.