Denver Radon ยท Home Field Guide
Radon, read like a building plan
A calm, source-grounded guide to testing a Colorado home for radon and understanding what a mitigation system actually does. Start with a reliable measurement, then work outward.
- About 1 in 2 Colorado homes tests above the EPA action level of 4.0 pCi/L, per CDPHE.
- Radon is colorless, odorless, and tasteless; testing is the only way to know your home.
- CDPHE reports that mitigation systems can reduce radon in any home.
Begin with a reliable test
Short-term kits run 48–120 hours; the building is closed for 12 hours first, then the device sits for 48 hours or more. Location matters as much as the number: place the kit in the lowest living area, 2–7 feet off the floor, away from exterior walls, doors, vents, and whole-house fans.
Read the result against official guidance
EPA recommends fixing a home at 4 pCi/L or above, and because no safe exposure level is known, considering fixes between 2 and 4 pCi/L. Homes with mitigation systems should be retested about every two years, per CDPHE and EPA.
Know the parts before you hire
Most effective systems are sub-slab or sub-membrane depressurization: a pipe draws soil gas from beneath the foundation and vents it above the roofline, driven by a fan. Caulking and sealing are part of the work but not a stand-alone fix, because the aim is holding conditioned air in, not blocking radon.
Understand mitigation system parts Questions for a radon professional Open the questions sheet
Where the official record lives
CDPHE cannot test homes and does not endorse listed contractors; those firms are certified by the National Radon Proficiency Program or the National Radon Safety Board and licensed through the Colorado Department of Regulatory Agencies. Cost context from CDPHE (retrieved 2026-11-01): typically about $1,000–$2,000 unless design problems appear. CDPHE's January 2026 announcement described a Low-Income Radon Mitigation Assistance program for qualifying owners; confirm current status with CDPHE.
Review the guidance notes CDPHE: testing and mitigating EPA radon program
