Radon Testing for Home Sales in Spokane, WA
Washington's disclosure law and typical buyer-seller practice around radon are often confused with each other. Here's what Form 17 actually requires, who usually pays for testing, and how to fit it into your closing timeline.
Is Radon Testing Required to Sell a Home in Washington
No, not directly, and this distinction matters. Washington law requires sellers to disclose known radon information as part of the Form 17 seller disclosure statement, under RCW 64.06.013, but it does not require radon testing itself as a condition of selling a home. That's different from a mandatory point-of-sale testing requirement. In practice, plenty of buyers order their own test anyway, whether or not the seller has ever tested, since a lender, agent, or the buyer's own due diligence often calls for it even where state law doesn't. If you're selling and have never tested, you can honestly answer Form 17's radon question based on what you actually know, which for most sellers means "don't know," rather than guessing.
What Washington's Form 17 Actually Asks About Radon
Form 17's Environmental section asks sellers: "Are there any substances, materials, or products in or on the property that may be environmental concerns, such as asbestos, formaldehyde, radon gas, lead-based paint, fuel or chemical storage tanks, or contaminated soil or water?"
Radon is named specifically, alongside asbestos and lead-based paint, not buried in generic language. Sellers answer Yes, No, or Don't Know based on actual knowledge, not a duty to investigate further before answering. If a seller answers Yes, meaning they know of a radon issue, typically a prior elevated test result, buyers cannot waive receiving that section of the disclosure. That's a meaningful protection: known radon information has to reach the buyer in writing, even though testing itself was never mandatory.
Who Pays for Radon Testing in a Home Sale
There's no fixed rule; it's negotiated like any other inspection cost. In practice, buyers commonly order and pay for radon testing themselves as part of their own due diligence, often scheduled alongside a general home inspection during the same visit. If the result comes back elevated, that's usually when negotiation starts: the buyer and seller work out whether the seller credits money toward mitigation, whether the seller has mitigation done before closing, or whether the buyer accepts the property as-is with that information in hand. None of that is dictated by state law; it plays out through the purchase and sale agreement like any other inspection finding.
Timing Testing Around Your Closing Date
A standard short-term professional test runs 48 hours once placed, plus scheduling and lab turnaround, so plan for roughly 3 to 5 days from ordering to a written report in most cases. Building radon testing into your inspection contingency window from the start, rather than requesting it once other inspection items are already resolved, avoids a last-minute scramble that can put your closing date at risk. If the result comes back elevated, you'll also want time left in your contingency period to negotiate before that window closes.
If the Test Comes Back Elevated
An elevated result during a transaction doesn't have to derail it. The same mitigation options covered on our radon mitigation page apply here: a qualified local professional designs a system around the home's foundation, and a retest afterward confirms the fix worked before or shortly after closing. If the property is new construction, check whether it was already built with the passive radon system Washington requires in Zone 1 counties; our new construction page covers what that includes and whether a fan needs to be added and activated. Either way, an elevated result is a solvable problem, not a reason to abandon the sale.
Request testing before your closing date
Call directly, or send a request and a qualified local pro will follow up.
Real Estate Radon Questions, Answered Straight
Is radon testing required to sell a home in Washington?
No. Washington law does not require radon testing as part of a home sale. It does require sellers to disclose known radon information, including past test results, in the Environmental section of the Form 17 seller disclosure statement. Many buyers and lenders request testing anyway, even though the state itself does not mandate it.
Who pays for a radon test during a home sale?
There is no fixed rule; it is negotiated like any other inspection cost. In practice, buyers commonly order and pay for radon testing as part of their own due diligence, often alongside a general home inspection, and then may negotiate mitigation costs or credits with the seller if the result comes back elevated.
What does Washington's Form 17 actually ask about radon?
Form 17's Environmental section asks sellers whether they know of any substances or conditions that may be environmental concerns, naming radon gas specifically alongside asbestos and lead-based paint. Sellers must answer based on actual knowledge, and if the answer is yes, buyers cannot waive receiving that section of the disclosure.
How long does radon testing take during a real estate transaction?
A standard short-term professional test runs 48 hours once placed, plus scheduling and lab turnaround, so plan for roughly 3 to 5 days from order to written report in most cases. Building that into your inspection contingency window, rather than requesting it at the last minute, avoids delaying closing.
See Washington's RRNC requirements
What Spokane County requires and how North Idaho differs.