Defect Library · Roseville, MNRadon in Roseville — Ramsey County EPA Zone 1
Radon is a naturally occurring radioactive gas that seeps from soil into basements. EPA classifies counties into Zones 1, 2, and 3 by predicted indoor levels. Ramsey County is Zone 1 — the highest tier.
What is Radon (Ramsey County Zone 1)?
Radon is a naturally occurring radioactive gas that seeps from soil into basements. EPA classifies counties into Zones 1, 2, and 3 by predicted indoor levels. Ramsey County is Zone 1 — the highest tier.
What do we find on Roseville inspections?
About 40% of Roseville basements we test are at or above 4.0 pCi/L. Older homes with unsealed sumps and exposed basement soil are the worst offenders.
History and background
EPA published its first national radon map in 1993, dividing US counties into Zones 1 (predicted average ≥ 4.0 pCi/L), 2 (2.0–4.0), and 3 (< 2.0). Ramsey, Hennepin, Anoka, and Dakota counties are all Zone 1. The Minnesota Department of Health has tracked indoor radon since the 1990s and published mitigation contractor licensing requirements in 2015.
How and why it fails
Radon is a decay product of uranium found naturally in soil and rock. It seeps from the ground through cracks in slabs, unsealed sump pits, plumbing penetrations, and porous foundations. In Roseville, glacial-till soil is permeable to soil gas. Once inside, it accumulates in basements and lower levels.
What we look for on the inspection
- Unsealed sump pit (the single most common entry point)
- Visible cracks in basement slab
- Bare-dirt crawlspace
- Passive radon stub-out installed but not activated (newer homes)
Repair cost breakdown
| Repair scope | Cost range | Notes |
|---|---|---|
| 48-hour CRM test | $150–$200 | Diagnostic. Required to know your level. |
| Active sub-slab depressurization | $1,500–$2,500 | Most common mitigation. Sealed pit + fan venting above the roofline. |
| Sub-membrane depressurization (crawlspace) | $2,000–$3,500 | For crawlspace foundations. |
| Post-mitigation re-test | $150 | Verify the system works. Required for many transactions. |
Code and regulatory references
Minnesota requires radon mitigation contractors to be licensed by the Department of Health. Builders of new homes since 2009 must install passive radon control as part of standard construction.
What should you do about it?
Active sub-slab depressurization mitigation runs $1,500–$2,500 installed by a licensed MN radon contractor.
How this connects to other Roseville defects
Era-defects rarely show up in isolation. A 1965 Roseville rambler that has one of these almost always has two or three more from the same construction window. Our defect library documents the full set we look for, and the inspection report cross-references findings so you can see the pattern.
Related defects in the same era window
Get this checked on your Roseville inspection
Call (651) 666-5602 or request an inspection quote. Radon (Ramsey County Zone 1) is included in every standard home inspection we perform. Same-week digital report with photos and prioritized repair recommendations.
Ready for a Roseville Home Inspection?
Same-week reports. Thermal imaging included. Era-specific findings for 1955–1975 ramblers, lakefront walkouts, and new-construction townhomes.