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Radon Testing & Mitigation

Radon is a soil gas that enters through the same foundation cracks and crawl space soil that let water and moisture in. Here is what testing and mitigation cost, how to read the numbers, and what the EPA county map can and cannot tell you.

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Frequently Asked Questions

How much does a radon mitigation system cost?

A residential system costs $800–$2,500 installed, with most homeowners paying about $1,200–$1,500 for standard sub-slab depressurisation.

Crawl spaces run higher — $1,500–$3,000 — because a sealed membrane has to go down before anything can be depressurised. Budget separately for the running costs: $60–$180 a year in electricity, and a $500–$1,100 fan replacement every 5–10 years.

What radon level is dangerous?

EPA sets the action level at 4 pCi/L — fix the home at or above that figure. Between 2 and 4 pCi/L, EPA suggests considering mitigation, because no level of radon is known to be harmless.

Below 2 pCi/L no action is generally recommended, though retesting every couple of years is sensible. For scale, the average outdoor level is about 0.4 pCi/L and the average US indoor level about 1.3 pCi/L.

Does my county's radon zone tell me whether my house has radon?

NoEPA classifies all 3,142 US counties into Zone 1 (predicted above 4 pCi/L), Zone 2 (2–4) and Zone 3 (below 2), which is useful for codes and for knowing whether to prioritise testing.

It cannot predict an individual building. Two homes on the same street routinely test very differently, because the result depends on the specific soil, foundation and ventilation beneath that house. Elevated homes have been found in every zone, including Zone 3.

Does crawl space encapsulation reduce radon?

PartlyAnd it is frequently oversold on this point. A sealed liner blocks the easiest path for soil gas and sealed crawl spaces do test lower, but the liner also traps gas beneath it.

Actual mitigation needs a vent pipe running under the liner to a fan that exhausts above the roofline. Test before encapsulating, and if levels are elevated have the mitigation designed into the job rather than bolted on afterwards. Retest after any encapsulation — the previous result no longer applies.

Who do I call right now for water damage?

Call (888) 840-6512. The line is answered 24 hours a day, seven days a week, and connects you with an IICRC-certified water damage restoration company that serves your area. Describe what you can see — where the water is coming from, how long it has been there, and whether it smells — the more specific you are, the faster the right company is on the line.

If the source is a pipe or an appliance, shut the main water valve first. Have four things ready and the call goes quickly: the address, when the water started, what is wet now, and whether you have filed an insurance claim.

Still not sure which of these is your situation? (888) 840-6512 · toll-free · answered 24/7