Vented crawl spaces are the Treasure Valley's number one radon entry path. A sealed sub-membrane system stops the gas at the source, and blocks the moisture, must, and cold floors that come with it.
Get a crawl space quote → (208) 510-0970Here's what that looks like. A heavy-duty membrane gets sealed across the entire crawl space floor and up the foundation walls, seams overlapped and sealed, piers wrapped. Suction piping runs underneath it to a continuously running fan that holds the space under the membrane at negative pressure. Radon gets pulled out and exhausted above the roofline before it ever reaches the crawl space air, let alone your living room. Full mechanics are on the mitigation page.
The side effects are the part homeowners end up loving. That same sealed membrane blocks ground moisture, which is what causes the musty smell, the damp sagging insulation, the sweating ducts, and a chunk of the cold-floor problem in winter. One system, two jobs: the radon number comes down and the crawl space turns from a damp dirt cave into a dry, sealed space.
Homes that are part crawl space, part basement, common in split-levels across Boise and Nampa's older neighborhoods, usually need a combined system tied to a single fan. That's sized on the quote, one flat number before work starts.
Not by itself. A standard vapor barrier slows ground moisture. Radon mitigation for a crawl space is sub-membrane depressurization: a heavy-duty membrane sealed across the floor and up the walls, with a fan pulling air from underneath it. The membrane blocks moisture as a side effect, so a properly built radon system doubles as premium moisture control.
Because so much Treasure Valley housing sits on them, and a vented crawl space is essentially open soil connected to your living room. The stack effect pulls crawl space air, radon, moisture, and all, up into the house. Idaho DHW specifically identifies crawl spaces and foundation gaps as the main entry paths.
Yes. A sealed membrane blocks ground moisture, which is what drives the musty smell, damp insulation, and a lot of the winter floor chill. Radon control and crawl space comfort are the same physics, managing what comes up out of the soil.
It's the higher end of mitigation pricing, typically $1,500 to $2,500 for a full sub-membrane system depending on crawl space size and access, versus $800 to $1,500 for a simple sub-slab system. You get one flat number before work starts.
Flat quotes on sub-membrane systems across Boise, Meridian, Eagle, Nampa, and Caldwell.
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