Montana Put Radon in the Real-Estate Paperwork Back in 1993
Montana was one of the early states to write radon into its real-estate law. The Montana Radon Control Act requires that every offer to purchase inhabitable property carry a radon disclosure statement — on a document the buyer signs before or at the same time as the offer. The statute (MCA § 75-3-606) even dictates the words, in capital letters:
“RADON GAS: RADON IS A NATURALLY OCCURRING RADIOACTIVE GAS THAT, WHEN IT HAS ACCUMULATED IN A BUILDING IN SUFFICIENT QUANTITIES, MAY PRESENT HEALTH RISKS TO PERSONS WHO ARE EXPOSED TO IT OVER TIME. LEVELS OF RADON THAT EXCEED FEDERAL GUIDELINES HAVE BEEN FOUND IN BUILDINGS IN MONTANA. ADDITIONAL INFORMATION REGARDING RADON AND RADON TESTING MAY BE OBTAINED FROM YOUR COUNTY OR STATE PUBLIC HEALTH UNIT.”
Two more things the law does: if the seller knows the property has been tested, the available results — and evidence of any mitigation work — must be handed to the buyer before or when the contract is signed. And sellers and agents who comply get statutory immunity from radon-related liability. That's the trade the Legislature wrote: put it on paper, share what you know, and you're protected.
Note what the law does not do: it doesn't require anyone to test. Which means every Montana closing carries a radon warning — and most carry no radon number. The buyer's inspector is usually the one who supplies it, ten days before closing, at maximum leverage.
If You're Buying: Test Before You Close
Cascade County is EPA Zone 1, and the county health department reports 60 percent of collected samples above the 4.0 pCi/L action level. In this market, skipping the radon test isn't optimism — it's buying a coin flip weighted against you. A professional 48-hour test slots inside a normal inspection window, and it's the one number the disclosure form can't tell you: what the house reads right now, measured by a device working for you.
- The result is high? Negotiate the fix like any inspection item. A standard system is a known four-figure cost with a published range — not a mystery.
- The disclosure mentions an old high test, but there's a system? Ask for the post-mitigation verification report. No report? Order a retest — 48 hours settles it.
- The house was never tested? That's the most common case, and the easiest: test now, while your inspection contingency is open.
If You're Selling: Get Ahead of the Form
The sellers who lose money on radon are the ones who learn their number from the buyer's inspector, ten days before closing, with zero leverage and a deadline. The sellers who don't are the ones who tested first. Test before you list: if it's low, you disclose with confidence. If it's high, you fix it on your schedule, at a price you chose, and your paperwork shows a mitigated home with a passing verification test attached. Under Montana's disclosure rules, that documentation works for you in every future showing — and because known results follow the house, a quiet high test never really stays quiet.
How We Work a Closing Timeline
Real-estate radon work is deadline work, and we build the schedule around the contract, not the other way around. A typical pre-closing sequence: firm written quote from the test report and foundation details the day you call · installation inside the week · 48-hour verification test immediately after · documentation packet to both agents before the walk-through. Install day itself is three to five hours, and nobody has to move out.
One honest note: we are the mitigation side, not a home inspector, and the verification test we run on our own installs is quality control — for the transaction's independent test, use your inspector's monitor. That separation protects everyone, including you.