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Do New Homes Have Radon? Testing and Radon-Resistant Features
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Why a new home is not exempt
EPA says radon comes from the natural decay of uranium in nearly all soils. It moves up through the ground and into a home through cracks and other holes in the foundation. EPA says local geology, construction materials and how the home was built are among the factors that affect radon levels.
What "radon-resistant" means
If a new house is built to be radon-resistant, EPA says it will include these basic elements:
- Gas-permeable layer under the slab or flooring, often a 4-inch layer of clean gravel. It is used with basement and slab-on-grade foundations, not crawlspace foundations.
- Plastic sheeting over that layer and under the slab. In crawl spaces, the sheeting goes directly over the crawlspace floor.
- Sealing and caulking of all below-grade openings in the foundation and walls.
- A vent pipe, 3 or 4 inches wide, running from the gas-permeable layer through the house to the roof.
- Junction boxes. One in the attic makes it easier to add a vent fan. Another in the living space powers the fan alarm.
EPA says these passive techniques can help reduce radon levels when installed properly and completely. It suggests asking your builder whether they use a recognized approach, such as International Residential Code Appendix F, ASTM E 1465-08 or ANSI/AARST RRNC 2.0.
What to do
- Test soon after you move in, even if the home is radon-resistant. See our test kit guide.
- If the result is 4 pCi/L or higher, EPA says a vent fan can be added to the passive system. Ask a qualified mitigator for an estimate. See how to find one.
- Test again after the fix. See radon tests after mitigation.
Buying a new home? Our home sale guide covers the steps. Use licensed pros for any electrical work and follow local codes.
Moved into a new home?
Testing is the only way to know your radon level. A mail-in kit is a low-cost way to start, and our guide shows how to place it so the result is reliable.
How to use a radon test kitBrowse radon test kitsCommon questions
Do new homes have radon?
They can. EPA says radon can be a problem in homes of all types: old homes, new homes, drafty homes, insulated homes, homes with basements and homes without basements.
Should I test a new home?
Yes. EPA says even if a new home was built to be radon-resistant, it should be tested for radon as soon as possible after occupancy.
What are radon-resistant features?
EPA lists five basic elements: a gas-permeable layer under the slab or floor, plastic sheeting, sealing and caulking of below-grade openings, a vent pipe from the gas-permeable layer to the roof, and an electrical junction box in the attic to make adding a vent fan easier.
What if my new home tests at 4 pCi/L or higher?
EPA says a vent fan can easily be added to a passive radon-resistant system to make it an active system. Consult a qualified mitigator to estimate the cost.
Is radon-resistant construction worth it?
EPA says including passive radon-resistant features during construction usually costs less than fixing the home later.
Related guides
Free printable: Radon Test Day Checklist
EPA's testing steps in one page, plus what your result means. Download the one-page PDF now, or get it by email along with a short series of five helpful emails.