A slab-on-grade or basement foundation gets a straightforward sub-slab depressurization system. A crawlspace needs a different approach, because there’s no slab to core into — just exposed soil under the house.
Why crawlspaces are different
Without a solid slab, radon (and moisture) can move up through open ground across the entire footprint of the crawlspace, not just through isolated cracks. The fix has to cover that whole surface area, not one suction point.
Vapor barrier plus sub-membrane depressurization
A heavy-duty vapor barrier gets sealed across the crawlspace floor and up the foundation walls, closing off that open-ground surface. A suction point is set beneath the membrane, connected to a fan the same way a sub-slab system would be — pulling soil gas out from under the barrier before it can rise into the crawlspace or the house above it.
Passive vs. active ventilation
Some crawlspaces rely on passive vents alone to manage moisture, without any mechanical suction. That can help with moisture but usually isn’t enough on its own for radon — a fan-driven system under the membrane is what actually creates the negative pressure needed to keep radon from working its way up.
Moisture and radon, handled together
The same vapor barrier that blocks radon also cuts down on the humidity and musty air that crawlspaces are notorious for. Homeowners dealing with both issues usually find one system solves both at once, rather than needing separate fixes.
Frequently asked questions
Will this stop my crawlspace from smelling musty?
Often, yes — sealing off ground moisture is a big part of what causes that smell in the first place.
Does a crawlspace system cost more than a slab system?
It depends on the square footage and current condition of the crawlspace — we quote based on what’s actually down there, not a flat rate.
Have a crawlspace with a high radon reading or a musty smell? Get a quote and we’ll walk the space with you.