Lowering Your Home's Radon Levels

Listed below are strategies used to reduce radon levels:

Mitigation

• Radon mitigation systems use sub-slab depressurization to prevent radon from entering your home by drawing the radon from below the house and venting it through a pipe to the outside air above your roof, pictured right.
• Radon mitigation systems can reduce radon to below 2 pCi/L.
• The video above illustrates how sub-slab depressurization works to reduce radon.

Cost: A certified contractor can install a radon mitigation system for around $1,200, although it can range from $800 to $2,000. Sub-slab depressurization is not a do-it-yourself project unless you have considerable contractor skills.

See our list of radon mitigation contractors, and visit "This Old House" to learn more about how mitigation systems are installed.

Sealing

Important note: sealing alone to reduce radon is not recommended. The sealing process, by itself, has shown to not reduce radon very much and it is not very consistent.

• All gaps and openings through basement floors and walls can be sealed with gas-tight materials. The caulk type with the best adhesion to concrete is polyurethane (not silicone).
• Since it can be inexpensive and does make mitigation systems more effective, it is worth a try, but one shouldn't expect it to have a major effect. It might reduce radon levels significantly if the area of openings that are sealed adds up to several square inches. Hairline cracks are not worth sealing.

Construction

Radon-resistant construction can be installed into new homes. Building radon resistance into a new house is cheaper than radon mitigation after construction as the needed building materials are common and the techniques are straightforward. Visit the Environmental Protection Agency's (EPA) webpage Radon-Resistant Construction Basics and Techniques to learn more about radon-resistant construction.

Additional resources

• U.S. EPA Booklet, Building Radon Out: a Step-by-Step Guide on How to Build Radon-Resistant Homes (PDF)
• Pictures, information, prices for radon mitigation supplies; pictures of mitigation system installations
• Pictures, information, prices for radon mitigation supplies
• Pictures, supplies, books and information for mitigation
• Information about radon for families, homeowners, builders and contractors

Radon mitigation system standards

To get the radon as low as reasonably possible, maximize durability, and minimize operating costs for homeowners, regulating states have adopted standards for mitigation systems. The US EPA document, Radon Mitigation Standards (PDF) has been the model. In it, some of the most important features for good mitigation systems are described in Sections 14.2 (vent pipe), 14.3 (fan installation) and 14.5 (sealing).