Who does this work
You may come across radon-only companies and other trades offering this work. Whichever you're talking to, ask how much of their work is radon systems, and have them walk you through your own house. A typical active system has a suction point, pipe, fan, exhaust and warning device, followed by a test to show it worked. The mitigation guide explains each one.
If you're thinking of doing it yourself
CDPHE says you "might be able to do sub-slab depressurization yourself," given good handyman skills, including electrical wiring. Larimer County warns that do-it-yourself systems "may not meet local building codes." Weigh both. If you sell later, a buyer will see what you built, and the disclosure law means they'll hear about it too.
Questions to ask a contractor
- Who will be at the house doing the work?
- Which standard do you work to? (Colorado's rules cite AARST standards. AARST revised its standards in 2023, and a state report says Colorado hasn't adopted those revisions, so ask which edition applies. There's no need to insist on one.)
- Where will the suction point, pipe, fan and exhaust go? Can I see the route before you start?
- Does the exhaust meet EPA's distances from windows, doors and other openings?
- What warning device will I get, and how do I read it?
- Will the system be labeled with who installed it, and when?
- Does this need a permit? Who pulls it? (Then confirm with the building department.)
- Who runs the follow-up test, and when? What happens if the number is still high?
- What's the warranty on the fan and on the work?
- Will you check my combustion appliances, or should I have someone else do it?
- How much is due before work starts, and when is the rest due?
- Can I have references?
What the contract should say
EPA's Consumer's Guide to Radon Reduction lists items for a contract: the total cost, the time needed, permits, and a question worth putting in writing, "A guarantee to reduce radon levels to 4 pCi/L or below?" Add the locations you agreed on, the fan model and warranty, who does the follow-up test, and any deposit, with when the balance comes due. EPA also says wiring "must be installed according to local electrical codes," and that "Radon reduction systems must be clearly labeled."
EPA's timing for the test after the install is "within 30 days of system installation, but no sooner than 24 hours." It also recommends an independent follow-up test of 2 to 7 days, which could be a measurement professional or a kit you run yourself.
Permits and local offices
Permit rules vary, and no local page reviewed for this site says whether adding a radon system to an existing home needs one. Call the building department before work begins. The contacts are on the Larimer County page. The City of Fort Collins points out "Work without a permit may cause problems when selling a home". That applies to building work in general, so it's worth a phone call.
What commonly goes wrong
- Finding out late. A state report says some owners don't learn systems "were installed improperly until they are selling their homes." Check the labels, the warning device and the follow-up result while the installer can still fix things.
- Accepting a sealing-only plan. "EPA does not recommend the use of sealing alone to reduce radon."
- Taking a radon number on faith. Keep your test reports. A seller has to share the most recent ones.
Who this page isn't for
If you're looking for help through the state's low-income program, that program has its own contractor process. Go to CDPHE directly. If you're looking for a reading and not a system, see the testing guide.
Questions homeowners ask
What should I settle before work starts?
Where the suction point, pipe, fan and exhaust go, what warning device you'll get, who runs the follow-up test, what the warranty covers and how payment works. Then get it in the contract.
How do I judge the work afterward?
Your follow-up test and the install section of the mitigation guide are how you judge it.
Can a plumber or electrician install a radon system?
Ask them the same questions you'd ask anyone, starting with how many radon systems they've put in. EPA says wiring "must be installed according to local electrical codes."
Can I do it myself?
CDPHE says you might be able to, and Larimer County warns about building codes. See the section above.
How this site helps
LarimerRadon.com is a referral service: a request here goes to one independent local contractor, who quotes and does any work directly with you. Ask them these same questions.
Sources
- Colorado Department of Regulatory Agencies, radon report (Oct 15, 2026).
- CDPHE, testing page (© 2026, undated).
- EPA, Consumer's Guide to Radon Reduction.
- Larimer County health page (Nov 1, 2026); City of Fort Collins, Building Permit Process.