Radon Testing on a Deal Deadline
An inspection window gives you days, not weeks. We arrange 48-hour continuous-monitor radon tests across the North Shore with reports delivered as soon as the device comes down, so the radon question gets answered inside your contingency period, not after it.
How the 48-hour transaction test works
A licensed measurement professional places a continuous radon monitor in the lowest level of the home that could be lived in, under closed-house conditions. The monitor logs radon hourly for at least 48 hours, records temperature, pressure, and power interruptions, and produces a timestamped report the moment the test ends. You get the EPA-protocol average plus the hour-by-hour graph, and so does the other side's agent, which is exactly why nobody argues with it.
Timing matters more in a transaction than anywhere else. Closed-house conditions need to hold starting 12 hours before the monitor starts logging, so on a typical inspection timeline the monitor should go in the same day as, or the day after, the general inspection. Scheduling the radon test last is how buyers end up asking for extensions.
What Illinois law actually requires
The Illinois Radon Awareness Act puts the obligation on disclosure, not testing: sellers must provide the state radon pamphlet and disclose known radon hazards or prior results before the buyer is bound. No statute forces a test — the inspection contingency is where buyers protect themselves. If a prior mitigation system exists, its vent-pipe tag with the installer's license number and the most recent test result become part of that disclosure picture, which is one more reason a tagged, tested system helps a sale rather than hurting it.
For sellers: test before you list
A pre-listing test costs little and removes the only radon scenario that genuinely damages deals: the surprise. Test low, and you disclose the result and move on. Test high, and you install a system on your own schedule at a normal price, instead of negotiating one under deadline pressure with a buyer holding leverage. Winter listings have an extra angle: closed-house season is when tests read highest, so a winter pre-listing test that comes back low is strong evidence in your favor.
For buyers and agents
Order the radon test with the inspection, not after it. If the result comes back at or above 4.0 pCi/L, the ask is straightforward: a mitigation credit or a seller-paid install with a verification test before close. The economics are small against a North Shore purchase price — most systems run $800 to $2,500 — but only if the finding lands while the contingency is still open. Our testing page covers the measurement methods themselves, and our suburb pages cover what local housing stock means for radon odds in Northbrook, Glenview, Wilmette, and Evanston.
Inspection window open? Get the monitor placed.
Call (224) 362-4440Frequently asked questions
Does Illinois require a radon test to sell a house?
No. The Illinois Radon Awareness Act requires sellers to give buyers the state's radon pamphlet and disclose any known radon hazard or prior test results, but it does not force anyone to test. In practice, buyers order the test during the inspection window, and on the North Shore most of them do.
Can a 48-hour test really be trusted?
When it runs on a continuous radon monitor, yes. A CRM logs the level hour by hour, flags power interruptions and tamper conditions, and reports an EPA-protocol average. That hourly record is exactly why lenders, attorneys, and both agents accept it: the result is auditable rather than a single number from a mailed-in envelope.
The test came back high. Is the deal dead?
Almost never. A high radon test is one of the cleanest inspection findings to resolve, because the fix has a known price and a verifiable result. Typically the parties negotiate a mitigation credit or the seller installs before close, and a verification test confirms the number dropped. Radon kills deals mainly when it surfaces late — which is an argument for testing early in the window, not for skipping it.
We waived the inspection. Should we still test?
Yes, after closing, for your own information. A test costs little, takes two days, and if the number is high a mitigation system is a one-day install. Waiving an inspection contingency is a negotiating decision; breathing the basement air is a daily one.