Radon for Helena home buyers and sellers
With roughly half of tested homes in the county at or above the action level, radon comes up in a lot of Helena sales. Here's what Montana law requires and how to keep a test on schedule.
Montana does not require a radon test to sell a house, but it does require a disclosure. Under Montana Code 75-3-606, a radon disclosure statement has to appear on at least one document signed before or with an offer on inhabitable property, and the buyer signs to acknowledge it. If the seller knows the building has been tested, the seller must give the buyer the results and any evidence of mitigation before or when the purchase contract is signed.
If you're buying
- The EPA recommends testing any home you buy, regardless of zone. Most buyers schedule it during the inspection period.
- If the house already has a system, ask for the installer's paperwork and the last test result, and look for a running fan and a manometer showing suction.
- The disclosure law doesn't create a contingency or a right to back out unless your contract says so. Talk with your agent about a radon clause.
- If the result is 4 pCi/L or higher, common options are a system installed before closing, a credit, or a plan to install one yourself after closing.
If you're selling
- Testing before you list keeps a surprise out of the buyer's inspection window.
- If you've ever tested, Montana law says you must share those results, so keep them with your house records.
- If you put in a system, keep the installer's details, certification number and the post-mitigation result for the next buyer.
How is a real estate test run?
Most are short-term tests with a continuous monitor under closed-house conditions. Opening windows, running fans that pull in outside air, or moving the device can throw off the result, and many monitors record tampering. Keep the house closed, and let the seller's household know the rules.
Can testing and a system fit before closing?
Usually, if you call early. Give the radon company your inspection deadline and closing date up front so it can schedule the test, the install and the follow-up test in order. Montana DEQ says the follow-up test should come no sooner than 24 hours after the system starts.
We don't publish or quote prices. The radon company prices the job after it understands your foundation, and usually after someone has walked through the house, so treat any figure given over the phone as a starting point, not a quote.
Where we connect you with help
Common questions
Is a radon test required to sell a house in Montana?
No. Sellers must provide the radon disclosure statement and any known test results and mitigation records, but the law doesn't require a test.
Who pays for a radon system in a sale?
It's negotiated between buyer and seller. Your real estate agent can advise on what's typical in your deal.
Related services
- Radon testing
- Radon mitigation systems
- Crawl space and mixed foundations
- Radon fan replacement and repair
More background: Montana radon guide.
Radon result came back over 4 pCi/L?
Call and get connected with a Helena-area radon company that can look at your foundation and design a system.