Radon Testing Basics For Franklin & Williamson County

If you are buying or selling in Franklin or anywhere in Williamson County, you have probably heard someone mention radon. It is invisible and odorless, which makes it easy to overlook during a busy move. Still, understanding radon can help you protect health, reduce surprises during inspections, and keep your deal on track.

In this guide, you will learn what radon is, how and when to test, what the numbers mean, and what to do if levels are elevated. You will also get a simple buyer and seller protocol tailored to local timelines. Let’s dive in.

What radon is and risk

Radon is a naturally occurring radioactive gas that comes from the breakdown of uranium in soil and rock. It can enter homes through cracks and openings in foundations and accumulate indoors. The U.S. Environmental Protection Agency and the Centers for Disease Control and Prevention identify radon as the second-leading cause of lung cancer in the U.S. and the leading cause among non-smokers, with an estimated 21,000 deaths per year nationwide.

The key point for homeowners is simple. You cannot see or smell radon, so testing is the only way to know your home’s level.

Franklin and Williamson context

Radon potential varies across Tennessee, including parts of Williamson County. Local geology and even house-by-house differences can lead to very different results on the same street. Do not assume a home is safe based on location or rumors. The Tennessee Department of Environment and Conservation (TDEC) provides state resources, maps, and education on local conditions. Check the TDEC Radon Program for current information, and use testing to confirm any property you own or plan to purchase.

When to test a home

You can test at any time, but certain moments are especially helpful:

• Before listing, so you can disclose results and reduce buyer friction.
• During the inspection period for a purchase, so you can negotiate confidently.
• After renovations that change ventilation or foundation conditions.

Test the lowest lived-in level. That could be a basement, a slab-on-grade first floor, or a crawlspace-adjacent level if it is heated and used. If multiple levels are regularly occupied, consider testing those as well.

Short-term vs long-term tests

There are two main approaches, and both are useful.

• Short-term tests: Typically 2 to 7 days. These are common in real estate timelines and include charcoal canisters or continuous radon monitors. They give you a quick screening.
• Long-term tests: At least 90 days. These average out seasonal swings and give a more representative annual exposure picture.

For short-term tests, keep “closed-house” conditions for 12 hours before and during the test. Keep doors and windows closed except for normal entry and exit. Place the test 20 to 40 inches above the floor, away from drafts, exterior walls, high humidity, and direct sun. Follow the device instructions closely.

How to read results

• Below 2.7 pCi/L: This is below the World Health Organization reference level. It is generally low concern, although lower is better.
• 2.7 to 4.0 pCi/L: This is below the EPA action level but above WHO’s reference. Consider a retest or mitigation depending on household factors and buyer preferences.
• At or above 4.0 pCi/L: The EPA recommends mitigation. For a short-term result at or above 4.0 pCi/L, confirm with another short-term test or, if time allows, a long-term test.

For real estate, a common approach is to confirm an elevated short-term result with either a second short-term test or an agreed plan to mitigate and then verify performance after installation.

Mitigation basics and costs

The most common fix is active soil depressurization, often called sub-slab depressurization. A contractor installs piping and a fan to reduce radon entry from the soil. Other approaches may include crawlspace ventilation and targeted sealing.

Typical costs often range from about $1,000 to $3,000, depending on the home’s size, foundation type, and complexity. Ask for a written proposal, a system diagram, and warranty details. After installation, complete a post-mitigation test to confirm levels drop below the target threshold.

Tips for real estate timelines

Here is a simple protocol you can follow in Franklin and Williamson County.

If you are selling (pre-listing)

1. Order a short-term test (48 to 96 hours) with a certified tester or a reputable kit. Maintain closed-house conditions.
2. If the result is below 4.0 pCi/L, include the report, date, and method in your disclosure packet.
3. If the result is at or above 4.0 pCi/L, choose one of three paths: confirm with a longer test before listing, disclose and offer a mitigation credit, or mitigate now and retest before going active.

If you are buying (offer and inspection period)

1. Include a radon-testing contingency and complete a short-term test within the inspection window.
2. If elevated, request confirmatory testing or mitigation according to your contract. Options include seller-paid mitigation, credits, or a price adjustment.

Regardless of side, document everything. Keep test reports, device details, and any mitigation proposals and verification tests. Clear records reduce friction later.

Choose certified pros

For measurement and mitigation, hire certified professionals. Use the National Radon Proficiency Program directory to verify credentials. You can also reference industry standards from the American Association of Radon Scientists and Technologists. Ask for:

• Certification details and references
• A description of the test method and quality controls
• A clear mitigation scope if needed, including expected performance and warranty
• A post-mitigation test plan to verify results

Local resources

• EPA radon overview: education, testing, and mitigation guidance from the EPA radon pages.
• Health guidance and safety information from the CDC radon program.
• Tennessee maps, education, and potential test-kit offerings through the TDEC Radon Program.
• Additional public health context from the American Lung Association on radon.

If you are planning a sale or purchase in Franklin or greater Williamson County, you do not have to navigate testing and timelines alone. For a calm, well-managed process that protects your interests, reach out to Unknown Company for guidance.

FAQs

Do Tennessee home sellers need to disclose past radon tests?

• Check current Tennessee disclosure requirements and standard forms, and consult the TDEC Radon Program or local real-estate counsel for the latest guidance.

What radon level requires action under EPA guidance?

• The EPA recommends mitigation when the long-term average is at or above 4.0 pCi/L, and to confirm any elevated short-term result with follow-up testing.

Can I use a DIY radon test kit for a Williamson County purchase?

• Yes. DIY kits are widely available, but many buyers prefer professional testing for documentation and credibility during negotiations.

How quickly can a radon mitigation system be installed?

• Many systems are installed in one day to a few days by a qualified contractor, depending on scheduling and home complexity.

Is radon higher in basements in Middle Tennessee homes?

• Often yes. Basements or the lowest lived-in levels can show higher levels because they are closest to the soil, but elevated radon can occur on any level, so testing is essential.