Radon-Resistant Construction

Updated 2026-05-17

Radon-resistant construction refers to building techniques and features incorporated into new homes to prevent radon gas from entering the indoor environment. These methods are particularly important in areas identified by the Environmental Protection Agency (EPA) as having a high potential for elevated radon levels (Radon Zone 1).

Key elements of radon-resistant construction typically include:

• Gravel layer: A layer of clean, coarse gravel beneath the slab or flooring system allows soil gases to move freely underneath the house.
• Plastic sheeting: A heavy-duty plastic sheet (6-mil polyethylene or equivalent) placed over the gravel layer and sealed at all seams and penetrations acts as a vapor barrier and helps block radon entry.
• Sealing and caulking: All openings in the foundation floor and walls, such as utility penetrations, control joints, and cracks, are sealed with caulk or other sealants.
• Vent pipe: A 3- or 4-inch diameter vent pipe extends from the gravel layer through the house and roof, providing a passive pathway for radon to escape. This pipe can be easily adapted for a fan if active Radon Mitigation becomes necessary.
• Junction box: An electrical junction box is installed in the attic near the vent pipe to provide power for a fan, should one be needed in the future.

For VA Loan Entitlement, Certificate of Eligibility (COE), and Loan Guaranty Certificate (LGC) involving new construction, builders may be required to certify whether a property was constructed using radon-resistant techniques and if it meets local building codes or state regulations for radon control. States may reference specific standards for radon-resistant construction, such as CCAH-2013 ("Standard: Reducing Radon in New Construction of 1 & 2 Family Dwellings and Townhouses").

References

1. 2026 VA Radon Testing: Required? Mitigation Costs Explained — valoannetwork.com
2. [PDF] State Multi-Family Radon Requirements State Certification — sosradon.org
3. [PDF] Radon Gas Certification for VA Builder Property - Windsor Mortgage — windsormortgage.com