Radon Mitigation
A large share of the older housing here sits over a crawlspace rather than a basement — the pre-war cottages in the Avenues, the early stock around Murray and central Bountiful, and almost any house that has been extended. There is no slab to drill and nothing airtight to seal to, so the fix is to build the barrier the house never had: a sealed membrane across the ground with the suction drawn from underneath it.
A crawlspace changes the problem completely. With a basement there is a concrete floor between the soil and the house, and the job is to depressurise the ground beneath it. In a crawlspace the soil is simply open to the underside of the building, separated from the rooms above by a floor that was never built to be airtight. There is nothing to drill through and nothing to seal to. The fix is to build the barrier that is missing.
A sealed membrane is laid across the entire ground surface, seams lapped and sealed, carried up the stem walls and sealed to them, and sealed around every pier and penetration. Suction is then drawn from underneath that sheet, which turns the whole crawlspace floor into one large collection area. Done properly it is very effective. Done to eighty per cent — a corner left short, a seam taped rather than sealed, the pier bases skipped — it leaks at exactly the points that were hardest to reach, and the reading reflects it.
The honest constraint on this work is not technique, it is the space. The pre-war stock in the Avenues and the older cottages around Murray and Bountiful frequently have partial crawls with eighteen to thirty inches of clearance, sometimes over uneven ground or rubble stone. Sheeting one properly is slow, awkward work carried out on your side in a space you cannot kneel upright in, and it takes as long as it takes. Anyone quoting one from photographs has not been under the house.
Extremely common here, and worth flagging because it is where systems most often come up short. A house that was extended, or built into a slope, frequently ends up with a basement under the original footprint and a crawlspace under the addition. Those are two different sub-slab environments, usually not connected to one another, and a system that treats the basement and ignores the crawl leaves a substantial part of the ground contact untouched. Both get looked at, and the design accounts for both.
A sealed, depressurised crawlspace usually also reduces ground moisture reaching the building, which tends to help with damp, musty air and the general condition of joists and ducting down there. That is a real and welcome consequence, and it is not the reason for the work. The reason is the reading, and the only evidence the work succeeded is the test afterwards. If you are not yet sure whether you have a problem at all, that starts with a 48-hour measurement.
How long does it take? One to two days depending on headroom, how much of the ground is obstructed by ductwork and piping, and whether the space has to be cleared first.
These usually come up in the same conversation:
The standard fix for a Salt Lake basement or slab-on-grade: suction under the floor, every gap sealed, a fan and a sealed riser to above the roofline — then a retest to prove it worked.
Learn More →A continuous monitor in the lowest lived-in level for 48 hours, logging hourly — so you get a curve you can read, not one number that might have been a fluke.
Learn More →An open sump pit is a hole straight into the soil. Sealing pits, cracks and penetrations is what makes the rest of a system work — and it is where cheap installs cut corners.
Learn More →Free · No Obligation
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