Do I Need to Test for Radon Before Selling My House in Spokane?

Why radon comes up so often in Spokane County

Radon is a radioactive gas that comes from uranium breaking down in soil and rock. You can’t see it or smell it. It moves up through the ground and into a house through cracks in the slab, gaps around pipes, sump pits, and bare dirt in a crawlspace, and it collects in the lowest living spaces.

Geology is the reason it gets so much attention here. The EPA’s radon map puts Spokane County in Zone 1, its highest category for predicted indoor radon potential. Then there is the housing stock. Older neighborhoods from Browne’s Addition to Hillyard have plenty of full basements, and a finished basement is exactly where a buyer’s inspector will set a monitor.

Two houses on the same block can read very differently, and only a test tells you about yours.

Is a radon test required to sell a house in Washington?

No state law requires a seller to test for radon before selling. What the law does require is honest disclosure, and the environmental questions on Form 17, Washington’s seller disclosure statement, name radon gas. A result you already have belongs on the form, along with any mitigation you did.

Testing before you list is really a choice about when you learn the answer, which the last section of this article takes up.

Short-term and long-term tests, and who runs them

Radon tests come in two lengths.

• Short-term tests run from a couple of days up to 90 days. Real estate tests are almost always short-term, usually a continuous radon monitor left in the lowest livable level for about two days.
• Long-term tests run longer than 90 days and give a better picture of the year-round average, which makes them useful for an owner who plans to stay and much less useful for a sale on a deadline.

During a real estate test, the house is kept closed: windows shut and exterior doors used only for normal coming and going, starting before the test and lasting until it ends. Many monitors log motion and power interruptions, so a window left open shows up in the report. Your listing agent should tell you when a buyer’s test is scheduled so the house is set up right.

Buyers typically hire their home inspector or a separate radon tester. Look for a tester or mitigator certified by one of the national programs, the National Radon Proficiency Program or the National Radon Safety Board. The Department of Health’s radon program is a good starting point if you want to test on your own first with a kit.

What a high reading means

The EPA recommends fixing a home when radon is at or above 4 picocuries per liter of air, written 4 pCi/L. Buyers and their inspectors generally treat that number as the line.

A high result is fixable, and it rarely ends a deal by itself. Someone installs a mitigation system, and the conversation turns to who pays for it and when.

How a mitigation system works

The usual fix in a house with a basement slab is called sub-slab depressurization. A mitigator drills a hole through the slab, pulls out some of the fill beneath it, and sets a plastic pipe in the opening. A fan somewhere outside the living space, often in the attic, the garage, or on an exterior wall, draws air from under the slab and vents it above the roofline. Inside, you see a white pipe rising from the floor. A small gauge on the pipe shows the fan is pulling.

Crawlspaces get a heavy plastic sheet sealed over the dirt with the suction pipe underneath it. Mitigators also seal the larger cracks and openings. After the system runs, a follow-up test confirms the level came down. Keep that retest. It is the document the next buyer will ask for.

How radon gets negotiated after a buyer’s inspection

When a buyer’s test comes back high, the inspection response usually asks for one of these:

• You hire a certified mitigator to install a system before closing, with a passing retest delivered to the buyer.
• You give a credit at closing, where the buyer’s lender allows it, and the buyer installs the system after moving in.
• A price reduction instead of a credit.

Having the seller install it is common because the buyer gets a retest before closing. The catch is time. The mitigator’s schedule plus the retest can press against the closing date, so get on a calendar the day the result arrives. A credit is simpler if your timeline is tight and the buyer is comfortable doing the work.

Cash buyers rarely ask for mitigation at all, which is one reason a cash offer request can be a reasonable comparison for an older house with other open questions too.

Should I test for radon before I list?

Testing first helps when your house has a basement or crawlspace and you would rather handle a possible fix on your own schedule. If the reading is high, you can install a system before listing, disclose the mitigation, and hand buyers a passing retest. That turns a likely inspection item into a line in the disclosure packet. It also gives you control over who does the work and what it costs.

Testing first helps less when you would not fix a high result anyway, for example if you are planning to sell the house as it is. Once you have a result you have to disclose it, and a high number on the form without a fix can make buyers nervous before they have even seen the place. Some sellers in that position skip the test and let the buyer’s inspection answer the question. Both approaches are legitimate, as long as what you know ends up on the disclosure.

A few practical notes. A buyer may run a new test even if you have one, so a result from a certified tester using a continuous monitor carries more weight than a kit from the hardware store. If the house already has a system, check that the fan runs and the gauge shows suction before photos, and gather the install paperwork and the last retest.

Radon comes up less in the Tri-Cities, where many houses are slab-on-grade or sit over crawlspaces with no basement at all. It can still be present in any house, and the only way to know is a test. The same basement buyers who ask about radon in Spokane often ask about old heating equipment too, which is covered in selling a Spokane house with an old oil tank, and the Spokane selling page goes through the rest of what inspectors check in older homes here.

Health questions about radon belong with the Washington State Department of Health.