Radon Testing When You Buy a Utah Home: What Buyers Should Know

Radon does not show up on a walkthrough. You cannot smell it, and a home can look immaculate and still test high. It comes up often enough in Utah transactions that buyers should plan for it — and it is one of the few inspection items a standard home inspection does not cover by default.

Here is what a buyer in Salt Lake, Davis, Utah, or Tooele County should know before the due diligence clock starts.

Why radon comes up so often in Utah

Radon is a radioactive gas produced by the natural breakdown of uranium in soil, rock, and water. It moves up through the ground and enters a home through cracks and other openings in the foundation, where the building traps it and it can accumulate.

The Utah Department of Environmental Quality reports that 1 in 3 homes in Utah have elevated radon levels. That is a large enough share to make testing a reasonable default here rather than an unusual precaution.

Two things worth clearing up:

• A newer home is not automatically safer. The EPA states that any home may have a radon problem — new and old homes, well-sealed and drafty homes, and homes with or without basements.
• A neighbor’s result tells you nothing reliable. The EPA addresses this as a myth directly, noting radon levels can vary greatly from home to home. The only way to know a specific house is to test that house.

On health, we defer to the EPA rather than characterizing the risk ourselves. The EPA states that radon is the second leading cause of lung cancer in the United States, that by its estimates it is the number one cause among non-smokers, and that it is responsible for roughly 21,000 lung cancer deaths a year. It notes the risk is especially high for people who smoke and live with high radon levels. Health questions belong with your doctor.

Radon is not part of a standard home inspection

This is the most useful thing to know going in. A general home inspection covers structure, roof, plumbing, electrical, and HVAC. Radon is a separate measurement, ordered separately, and it takes time to run.

Most inspectors in the Salt Lake area offer it as an add-on, often alongside a sewer scope. But it is opt-in. If you assume it is bundled and it is not, you can reach the end of your objection window with no radon data and nothing to raise.

Order it when you schedule the general inspection, not after the report comes back — a test that starts late may not finish in time to matter. The EPA also notes buyers frequently want testing done by someone not involved in the sale. If that matters to you, say so early.

Short-term and long-term tests, and which fits a purchase

The EPA describes two categories. Short-term tests remain in the home for two days to 90 days, depending on the device, and are the quickest way to test. Long-term tests remain for more than 90 days and are more likely to reflect the home’s year-round average.

Radon levels vary day to day and season to season, so a short-term test is less likely to capture a true annual average.

In practice, a purchase timeline does not accommodate a 90-day test. A short-term test is the normal choice during a transaction, and the EPA’s guidance accounts for this: if you need results quickly, a short-term test followed by a second short-term test may be used to decide whether to fix the home.

Conditions matter for a valid result. The EPA calls for closing windows and outside doors and keeping them closed as much as possible during the test. For a test lasting only two or three days, they should be closed at least 12 hours beforehand, and the EPA advises against running those short tests during unusually severe storms or high winds. The kit goes in the lowest lived-in level, in a room used regularly — not a kitchen or bathroom — at least 20 inches above the floor, away from drafts and exterior walls.

What the 4 pCi/L action level actually means

The EPA recommends fixing your home when radon levels are 4 pCi/L or more. The State of Utah uses the same figure.

Read that number correctly. It is an action threshold, not a safety line. The EPA is explicit that no level of radon is safe and that levels below 4 pCi/L still pose some risk and can often be reduced. A result of 3.8 is not a clean bill of health, and a 4.7 is not an emergency — it is a number that triggers a recommended response.

The EPA’s testing sequence:

1. Take a short-term test. If the result is 4 pCi/L or higher, take a follow-up test.
2. Follow up with a long-term test for a better sense of the year-round average, or a second short-term test if you need results quickly. If the first short-term result is more than twice the 4 pCi/L action level, the EPA says to take a second short-term test immediately.
3. Fix the home if a long-term follow-up reads 4 pCi/L or more. If you used a second short-term test, consider fixing if the average of the two is 4 pCi/L or higher.

Utah DEQ adds guidance for the middle range: for results between 4 and 6 pCi/L, consider a long-term test. For results below 4 pCi/L, retest every two to five years.

What mitigation typically involves

Mitigation is a well-established repair, not an exotic one.

For homes with a basement or slab-on-grade foundation, the usual approach is active subslab suction, also called subslab depressurization — which the EPA calls the most common and usually the most reliable radon reduction method. One or more suction pipes go through the floor slab into the crushed rock or soil underneath, and a fan draws the soil gas out and vents it above the home. Homes over a crawlspace are often handled with submembrane suction, which covers the earth floor with a high-density plastic sheet and vents from beneath it.

The EPA states that some radon reduction systems can reduce levels in a home by up to 99 percent.

On cost, we would rather be straight than quote a number we cannot stand behind. The EPA does not publish a fixed price. It says most homes can be fixed for about the same cost as other common home repairs, and that costs vary with the size and design of your home and which reduction methods are needed. Get written estimates from more than one qualified radon mitigation contractor. The EPA recommends using a certified or qualified contractor rather than doing the work yourself, because doing it wrong can raise your radon level or create other hazards.

Two notes for after you close: the fan is designed to run continuously and should never be switched off, and the EPA advises retesting at least every two years.

Where radon fits in your inspection objection window

Under Utah’s standard Real Estate Purchase Contract, your due diligence period is the window in which you evaluate the property’s condition and deliver any objections. We are deliberately not quoting a day count, because those deadlines are negotiated per contract and the dates on your REPC are the only ones that govern your deal. Your agent should calendar them the day you sign and tell you the exact date objections are due.

What matters for radon is sequencing. The test has to be ordered, run its full duration, and come back from a lab before you can object to anything it shows. That is the constraint that trips buyers up, not the negotiation itself. So order the test when you book the general inspection, confirm how long the device sits and when results return, and leave room for a follow-up if the first result lands at or above 4 pCi/L.

If a result comes back elevated, it is negotiated like any other finding. Sellers sometimes install a system before closing, sometimes offer a credit, and sometimes decline. Which outcome is realistic depends on your contract and how competitive the offer environment was. Our guide to home inspection negotiations in Salt Lake County covers how to prioritize requests so a reasonable ask does not get lost in a long list.

A mitigation system is also not a stigma. A house with a documented, working system and a post-mitigation result is in a better known state than an identical house that was never tested.

Planning inspections before you are under contract

The buyers who handle radon calmly decided to test before they wrote an offer. It is a line item you plan for alongside the general inspection and a sewer scope, not a decision you make under deadline pressure.

If you are early in the process, our first-time home buyer guide for Utah walks through the path from pre-approval to keys, and our breakdown of what happens after your offer is accepted lays out how the contract period unfolds.

We work with buyers across Salt Lake, Davis, Utah, and Tooele counties. We will make sure radon is on your inspection list from the start and every contract deadline is calendared. If you are getting ready to start looking at homes or want to talk through your timeline, reach out and we will walk you through it.

Test the house you are buying. Read the number for what it is. Then handle it inside your window.