What is a Radon Seal?

A radon seal provides a protective barrier in basements against infiltration from soil or water, which typically contain harmful radon gases. After determining that there are unsafe radon levels in a home, the owners perform a radon inspection, assessing the areas of possible contamination. The homeowners then implement do-it-yourself radon mitigation methods or contract professional radon services to apply a radon seal.

A radon inspection involves locating areas within a basement that provide access for harmful gases. Cracks in floors and wall foundations, floor drains and sump pumps are the usual culprits. Likewise, crawl spaces containing soil are generally rich in radon emissions. The space between the basement foundation and the upper floor provides a means for radon to enter the living area of a home. Environmental protection experts recommend that all of these locations receive treatment in order to ensure an effective radon seal.

Basement waterproofing generally involves using a product that prevents moisture from seeping through naturally porous concrete, but this type of product generally coats the outside surfaces only, in hopes of preventing water from entering the basement. Researchers suggest that while these products provide a temporary solution to moisture problems, most do not produce an effective radon seal. Many also contain dangerous chemicals, including benzene or xylene. Various chemical constituents may be combustible, produce harmful vapors or contain proven carcinogens.

Typical radon sealant products contain petroleum-based acrylics in an oil or water suspension. These concrete sealers not only protect the surface but also penetrate the capillaries and pores of cement. This permeating action forces soil and water back toward the exterior of the home. As a radon seal formulation enters the concrete, it also reacts with alkalis and calcium, forming a gel-like substance. Over time, the gel becomes increasingly hard, forming a moisture and gas resistant barrier.

Homeowners generally apply radon sealants by spraying the product onto the floor and foundation walls. Manufacturers suggest that two or three applications of the product are required in order to provide an effective seal. Various formulas are available for use on smooth, unpainted and unsealed concrete, but some products are ineffective where moisture is an existing problem. Once applied, radon seal products appear invisible and do not alter the surface of the concrete.

While many manufacturers boast lifetime warranties on radon seal products, the Environmental Protection Agency (EPA) suggests testing for radon levels every two years. The EPA also recommends using radon seal products in conjunction with various ventilation and exhaust systems in order to eliminate radon gas existing in the air.