Two things in Colorado's ground can affect a home: a naturally occurring gas called radon, and clay soils that swell and shrink. Both are common, both are manageable, and both are worth checking for when you buy.
Radon
Radon is a radioactive gas that seeps up from the soil and can collect indoors. Long-term exposure raises lung-cancer risk, and Colorado has high radon potential across much of the Front Range, so testing is a routine part of buying a home here.
- Test during due diligence. A short-term test by a professional is standard.
- Know the number. The EPA recommends taking action at 4 picocuries per liter or higher.
- Mitigation works. A system with a vent pipe and fan typically reduces levels significantly. It is a common, comparatively affordable fix, and sellers and buyers often negotiate who pays.
- Retest occasionally. Levels can change after renovations or over time.
Expansive soils
Many Front Range neighborhoods sit on clay soils that swell when wet and shrink when dry. Over the years this movement can crack foundations, slabs, driveways and walls, and cause doors to stick.
- Look for warning signs. Cracks in foundation walls or drywall, sticking doors and windows, uneven floors and gaps around trim can all be signs.
- Drainage matters most. Water pooling near the foundation makes movement worse. Grading should slope away from the house, and gutters and downspouts should carry water well clear of it.
- Get an expert opinion. If an inspection raises concerns, a structural engineer can say whether the movement is minor or needs repair.
- Newer homes are often built with foundations designed for these soils, such as drilled piers.
Tips
Ask sellers about past foundation repairs and radon systems, and get documentation. Keep water away from your foundation and avoid overwatering landscaping right next to the house.
General information only. A licensed inspector or engineer can evaluate a specific property.