Full basements are common in Cheyenne. They're dug below the frost line anyway, and many homes in the capital's older neighborhoods and post-war subdivisions have them. You'll also find garden-level basements in split-levels, and slab-on-grade ranches in some newer developments. Concrete foundations like these are where most local radon mitigation happens, and the method is the same in each case: sub-slab depressurization.
How a basement lets radon in
A basement is a concrete box sitting in soil, and radon gets in through the gaps:
- The joint between the floor and the walls, where the slab was poured against the footing.
- Cracks in the slab or walls, including shrinkage cracks that appear as concrete cures.
- Sump pits and floor drains.
- Plumbing and utility penetrations, especially under tubs and in mechanical rooms.
- The hollow cores of concrete-block walls, which can carry soil gas up and out at the top of the wall.
Basements also sit deepest in the soil and stay at the lowest pressure in the house, so they're usually where the highest readings show up.
Sub-slab depressurization, explained
A sub-slab system creates a vacuum field beneath the floor. The basic sequence:
- Communication test. The installer drills a small hole and checks how well suction spreads under the slab. Clean gravel spreads it widely; dense soil doesn't.
- Suction point. A hole of a few inches is cored through the floor, often in a utility room or unfinished corner, and some fill is removed underneath to make a small pit.
- Pipe run. PVC pipe rises from the pit, through the floor above or out through the rim joist, toward the fan.
- Fan. The fan is mounted in the attic, the garage, or outside, never in the basement or living space.
- Discharge. The pipe exits above the roof, away from windows.
- Sealing. The floor-wall joint, open cracks, and the sump get sealed so the system pulls soil gas, not room air.
- Verification. A manometer is installed and a follow-up radon test confirms the new level.
Questions about a reading? A certified Cheyenne-area pro can help. (307) 317-5825
Sump pits
If your basement has a sump connected to perimeter drain tile, it can be an excellent suction point because the drain tile runs right around the foundation where much of the radon enters. The lid has to be airtight. Clear lids let you see the pump, and a sealed lid can still allow for service.
Block walls
Older basements built from hollow concrete block sometimes need extra attention. If sub-slab suction alone doesn't reach the target, the installer may seal the top of the block walls or add suction to the wall cavities. Ask during the assessment whether your walls are poured concrete or block.
Finished basements
Finished basements are popular in Cheyenne for extra bedrooms and family rooms, and that's exactly the space you most want protected. Finishes make installation harder, though: carpet and pad over the slab, framed walls hiding the floor-wall joint, and limited unfinished space. Installers usually look for:
- A mechanical room, under-stair closet, or storage room for the suction point.
- A path straight up through a closet stack to the attic, or out through the rim joist into the garage.
- Spots where accessible sealing will make a difference without tearing out finishes.
If you're about to finish a basement, test first. Installing a system before the drywall goes up is much easier.
Slab-on-grade and garden-level homes
Slab ranches are often the simplest homes to mitigate. A single suction point through the garage slab or a closet floor can cover the whole footprint when there's gravel underneath. Split-level and garden-level houses can be trickier because part of the slab sits at grade and part below, sometimes poured separately. Separate slabs may need separate suction points.
Where the pipe goes in a Wyoming winter
Because of freezing and condensation, many cold-climate installers favor routes that keep most of the pipe inside the heated envelope or the garage:
- Up through the house: a closet or chase from basement to attic, fan in the attic, roof penetration. Nearly invisible outside.
- Through the garage: the pipe exits into the attached garage, the fan mounts there or in the garage attic, and it vents above the roof.
- Exterior wall: quickest, but the pipe and fan sit in the cold and wind, so drainage slope and freeze protection matter more.
Questions about a reading? A certified Cheyenne-area pro can help. (307) 317-5825
Results and costs
A properly designed sub-slab system typically drops basement radon well below 4 pCi/L. Many certified installers guarantee that number in writing and come back to adjust the system if the post-mitigation test is high. As a national benchmark, Angi's 2026 data puts active suction systems at about $805 to $1,326, with an average near $1,043. Finished basements, block walls, multiple slabs, and interior routes can raise the total. Prices come from the individual professional after an assessment; these are typical national ranges only.
Before you call
Have your test result handy, along with the basement type (full, garden, partial, block, or poured) and whether there's a sump. That's enough for a certified professional to plan a visit.
Frost depth, soils, and Cheyenne basements
Foundations in Cheyenne are built below the local frost depth, which is one reason full basements and garden levels are so common here: once you've dug that deep, adding a basement is a relatively small step. The soils those basements sit in vary. In some areas the backfill and native material are coarse, gravelly sediments derived from the granite of the Laramie Range, which let soil gas move easily toward the foundation. Elsewhere, finer silts and clays slow it down. That variation is exactly why installers do a communication test instead of guessing.
Basement questions we hear
Will sealing cracks alone fix it?
Usually not. The EPA notes that sealing by itself hasn't been shown to lower radon significantly or consistently. It works best as part of a depressurization system.
Can I keep using my basement during installation?
Generally yes. Work is concentrated around the suction point and pipe route, and most single-point systems take about a day.
What about radon from a basement sump with a pump?
A sealed sump lid can include a pass-through for the pump's discharge and power cord, so the pump keeps working while the system draws from the drain tile.
Questions about a reading? A certified Cheyenne-area pro can help. (307) 317-5825