Selling a House With a Radon Problem
3 min read · Last updated 2026-08-05 · Reviewed by Joseph Mena, CFO of Cash Flow Deals.
A radon test that comes back above the EPA's action level of 4.0 pCi/L gives most buyers the contractual right to ask for mitigation or walk away. You typically pay for the mitigation system, which usually costs between $800 and $2,500, and the sale is delayed until the retest clears. With us, you choose between the Fast Cash Offer, where we buy your house as-is and close without requiring you to mitigate or retest, and the Premium Cash Offer, where a pre-approved FHA or conventional buyer we already have, ready to go, pays more and buys directly from you. On Premium, only what the buyer's lender requires gets fixed, with repair costs settled from the sale proceeds out of our share. We cover repair costs, and we figure out a way, so nothing comes out of your pocket.
| Factor | Traditional Route | Cash Flow Deals |
|---|---|---|
| Failed radon test | Buyer can request mitigation or cancel, adding 1 to 3 weeks for install and retest | Sale moves forward with no retest required |
| Mitigation cost | Seller usually pays $800 to $2,500 out of pocket before closing | Seller pays nothing toward mitigation |
| Closing timeline | Can slip 30 to 60+ days waiting on contractor scheduling and lender sign-off | Closing date set by the seller, not a retest |
How a radon test derails a financed sale
Most standard purchase contracts give the buyer a set inspection window to test for radon, and if the result comes back above the EPA's 4.0 pCi/L action level, the buyer usually gets the right to demand mitigation or terminate the contract. Lenders don't want to fund a loan on a home with an open health flag, so even a motivated buyer's financing can stall until a mitigation system is installed and a follow-up test confirms the level dropped. That single test result can turn a 30-day closing into a two-month wait.
Who actually pays for radon mitigation
In most negotiations the seller pays, either because the contract defaults that way or because the alternative is losing the buyer. A standard sub-slab depressurization system, the most common fix, runs roughly $800 to $2,500 depending on the home's foundation and size. On top of that cost, the seller is usually the one scheduling the contractor and waiting on the retest, since the buyer's financing is on hold until it clears.
What you're actually required to disclose
If you've had a radon test done and know the result, most states require you to disclose that information to a buyer once you're under contract or before, even if you never fixed the problem. Disclosure rules on radon specifically vary by state, so check your state's specific requirements before you sign anything, but the safe default is: if you know a number, put it in writing.
Radon and mortgage approval
FHA and VA loans don't require a radon test as a condition of the loan itself, but if a test was done and the result is on file, an elevated reading can become a condition the lender wants resolved before funding. Conventional lenders generally follow the buyer's contract terms, meaning if the purchase agreement makes mitigation a condition, the lender will hold funding until that condition is met.
Selling as-is with the radon result in hand
Cash Flow Deals gives you the choice between the Fast Cash Offer, where we buy your house as-is and close, and the Premium Cash Offer, where a pre-approved FHA or conventional buyer we already have, ready to go, pays more and buys directly from you. You share the radon test result you already have so you can compare both paths. For either offer, the number is agreed before any work starts, and it changes only if you agree. The one exception: if something structural surfaces that was not visible or disclosed before we signed — foundation issues, hidden moisture, old wiring, cast-iron drain failure — we re-cost it and bring the number back to you. You decide. You can walk away. We disclose what we know at offer time so this almost never happens. With Premium, any mitigation or retest the buyer's lender requires must be completed for that loan to close. We cover repair costs, and we figure out a way, so nothing comes out of your pocket; only lender-required work gets done, and those costs are settled from the sale proceeds out of our share, not your agreed number. If your Premium Cash Offer buyer's loan falls through, that is our problem, not yours, and you can still take the Fast Cash Offer at its own number.
Common questions
What radon level fails a home inspection?
There's no official pass or fail line, but the EPA sets 4.0 picocuries per liter (pCi/L) as the level at which it recommends taking action. Most purchase contracts use that same number as the trigger for a buyer's right to request mitigation.
Do I have to disclose radon test results to buyers?
In most states, yes, if you know the result. Radon-specific disclosure rules vary by state, so check your state's exact requirement, but withholding a known elevated result you have on paper is a risk almost nowhere worth taking.
How much does radon mitigation cost?
A standard sub-slab depressurization system typically costs $800 to $2,500 installed, according to EPA guidance, though larger or more complex foundations can push that higher.
Can I sell my house without fixing the radon?
Yes, but a financed buyer's lender or contract may require it to be fixed before closing. Selling directly to a company that buys as-is skips the mitigation requirement entirely.
Will a radon problem scare off cash buyers?
Some will pass or lowball once they see the number, since mitigation is a real cost. A direct buyer prices the home once, radon result included, instead of renegotiating after the report lands.