Why radon deserves its own test
A standard home inspection does not measure radon. It is a separate test with its own protocol and its own device, and it is the only way the topic gets addressed before you own the house. Once you close, an elevated level becomes your problem and your expense.
When to test
Order the radon test at the same time you schedule the general inspection, on day one of the inspection period. The test itself takes 48 hours, and you want the remaining days for negotiation — not for waiting on a lab.
Radon timeline inside a home sale
Typical scheduling. Actual dates depend on contractor availability and your contract terms.
Order the radon test at the same time as the general home inspection. Closed-house conditions start 12 hours before the device is placed.
Reading the result
pCi/L reference table
Levels reflect EPA guidance for residential indoor air.
| Level | What it means | Recommended action |
|---|---|---|
| 0.0 – 1.9 pCi/L | At or below typical US indoor average (1.3 pCi/L) | No action needed. Retest in about two years. |
| 2.0 – 3.9 pCi/L | Elevated but below the action level | EPA suggests considering mitigation. A long-term test helps confirm. |
| 4.0 – 7.9 pCi/L | At or above the EPA action level | Mitigation recommended. |
| 8.0 – 19.9 pCi/L | Two to five times the action level | Mitigate promptly. |
| 20+ pCi/L | Substantially elevated | Treat as urgent; mitigate as soon as possible. |
Your options when the result is elevated
| Option | What it looks like |
|---|---|
| Seller mitigates before closing | Cleanest outcome; ask for the verification test result too |
| Seller credit at closing | You control contractor choice and schedule the work after you move in |
| Price reduction | Similar to a credit; depends on how your lender treats it |
| Proceed as-is | Reasonable at marginal levels if you plan to mitigate yourself |
If the home already has a mitigation system
- Ask for the original pre-mitigation and post-mitigation test results.
- Check that the manometer shows an offset between the two liquid columns.
- Confirm the fan is mounted outside living space and the exhaust is above the roofline.
- Test anyway. A system that exists is not the same as a system that works.
- Ask when the fan was installed — replacement typically falls in the 8–12 year range.
What to ask for in writing
- 1The measured pre-mitigation result and test conditions.
- 2A description of the installed system, including suction point count and fan model.
- 3The post-mitigation verification result.
- 4Any workmanship terms the installing contractor provides.
Common questions
Almost never on radon alone. It is a one-day, well-understood fix with a measurable result — far more predictable than most inspection findings.
Related services
Keep learning
- Selling a Home With Radon: A Seller's GuideRadon discovered during a buyer's inspection is a negotiation. Radon discovered before you list is a line item you control.
- EPA Radon Action Levels ExplainedTwo numbers drive nearly every radon decision: 4.0 pCi/L, where the EPA recommends action, and 2.0 pCi/L, where it suggests considering it. Here is what sits behind them.