A passive radon system in a new home does not prove that the house has been tested or that its indoor radon level is low. The system gives soil gas a route to escape without a powered fan. EPA says testing is the only way to know whether a new house has a radon problem.

For buyers, buyer agents and builders, a complete handoff connects the installed equipment, test results and responsibility for any remaining work. Add these checks to your new-home purchase preparation.

Confirm what the builder installed

Ask the builder to show you the labeled radon vent pipe and explain its route from beneath the foundation to its roof outlet. For a typical slab system, EPA describes a gas-permeable layer beneath the slab, plastic sheeting, sealed foundation openings, a vent pipe and an electrical connection for a future fan. Designs vary with the foundation.

• Confirm the system type in writing. A passive system relies on natural air movement. An active system adds a powered fan in the vent pipe.
• Locate the provisions for a fan. Ask where the fan would go and whether its electrical supply is installed.
• Request evidence of concealed work. Obtain plans, installation records and available construction photographs.

An outlet beside a pipe shows preparation for a fan; it does not establish that one is installed. EPA’s activation bulletin illustrates the distinction. Resolve the equipment scope alongside other new-construction decisions, while specifications can still be clarified.

Schedule testing after construction

Schedule testing for after construction is complete, when proper test conditions can be maintained. EPA’s February 2020 technical bulletin recommends testing before occupancy. Its new-home guidance also calls for testing immediately after moving in, so put that check on the homeowner’s calendar.

• Agree on the location and method. EPA’s buyer guidance calls for testing the lowest level that could be used regularly.
• Protect the test conditions. For a two-to-four-day test, EPA specifies closed-house conditions for at least 12 hours beforehand and throughout testing. Windows stay closed; exterior doors open only for normal entry and exit. Follow the tester’s instructions, including normal heating and cooling operation. For tests lasting less than a week, use only air conditioning that recirculates interior air.
• Allow time for testing and the report. EPA specifies at least 48 hours of testing; some devices require longer.

These are highlights of EPA’s March 2024 testing checklist, pages 20–21, not a complete testing protocol. Coordinate remaining construction work with the tester.

Put payment and follow-up duties in the agreement

Do not assume “radon-resistant construction” includes testing, a fan or a promised result. EPA’s buyer guide, page 8 recommends addressing testing and mitigation responsibilities in the purchase contract.

Before signing or amending the agreement:

• Name who orders and pays for initial testing.
• Specify the result that triggers corrective work and who pays for the fan, electrical work and other necessary corrections.
• Assign responsibility for follow-up testing and sharing the complete report.
• Set deadlines and address what happens if results or corrections remain outstanding at closing.
• Clarify any warranty, exclusions and responsibility if the follow-up result misses the agreed target.

EPA recommendations do not determine your builder’s contractual obligations. Ask a local real estate attorney to review unresolved terms, and confirm applicable requirements with the local building department or state radon office.

Decide whether to activate, then verify the result

EPA recommends fixing homes at 4 picocuries per liter (pCi/L) or higher and considering reduction between 2 and 4 pCi/L. Below 4 does not mean risk-free. Have the tester explain the result and any confirmation needed under the applicable testing protocol.

A qualified radon contractor can assess the installed system and add a fan to make it active. Obtain a written scope; do not assume every pipe installation needs only a fan. EPA’s activation guidance recommends using a credentialed or licensed contractor as applicable to state requirements.

After activation, arrange another radon test. EPA’s 2025 consumer guide, page 13 recommends post-mitigation testing within 30 days of installation, no sooner than 24 hours after the system begins operating. It also recommends an independent follow-up measurement.

Retain a usable homeowner handoff file

Keep installation plans and photographs, installer contacts and all test reports together with the signed allocation of responsibilities. Include correction invoices, operating instructions and warranties. Label each test by date, location, method and whether the system was passive or active.

For an active system, ask for a demonstration of its warning device and maintenance instructions. EPA’s operating guidance says the fan should run continuously and recommends retesting at least every two years.

For any unfinished work, record the responsible party, deadline and evidence needed to close the item. A fan invoice documents installation; the subsequent radon report records the measured indoor level.