Radon testing notes for Denver buyers, sellers, and agents

This is a field note, not legal advice and not a contract clause. CDPHE encourages buyers to test during inspection and to hire a licensed radon measurement professional. The device CDPHE names for that job is a professional-grade continuous monitor or another approved test device. The location is the lowest area that could be turned into living space, which may be an unfinished basement the sellers never use.

A charcoal kit on the kitchen island is a weak exhibit in a negotiation. If you are the listing agent, the better move is to test before the house is listed, save the report, and fix a confirmed problem so it is not a last-week surprise. EPA’s Citizen’s Guide says homes where radon was reduced have not been a special barrier to selling, and that the fix can be a selling point. Hand the buyer the report, the dates, and the floor plan spot. Do not round a 4.6 down to “about 4.”

Sellers and buyers can negotiate who pays for a system. CDPHE’s usual Colorado cost talk is about $1,000 to $2,000 unless the layout is hard. That is a state figure, not a bid. The person who installs it needs a DORA mitigation license. National certification alone is not the lookup your client should rely on.

Colorado’s August 7, 2023 landlord disclosure rule, SB23-206, is a rental rule. Do not paste it into a purchase contract and call it the sale law. For a purchase, follow CDPHE’s transaction guidance and the forms your brokerage actually uses.

American Radon Systems installs in the Chicago area. It is not a Denver contractor. Do not tell a client an out-of-state company will pull a local permit. Point them at DORA’s roster.

Share the public guide, not a screenshot of a zone map, when a buyer asks whether “Denver is a radon city.” The accurate answer is that the county is Zone 1, and the house still needs its own test.