One day of work, a guaranteed result, verified in writing.
The standard fix is active sub-slab depressurization, and the principle is simple. A suction point is cut through the slab into the gravel or soil below. A sealed pipe runs from that point up through the house or along an exterior wall, and a quiet inline fan pulls soil gas out from under the foundation and vents it above the roofline, where it disperses harmlessly. Because the fan keeps the area under the slab at slightly lower pressure than the house, radon stops being drawn inside and goes out the pipe instead.
Done properly, this cuts indoor radon by 80 to 99 percent. It is not a filter, there is nothing to replace monthly, and the fan uses about as much electricity as a light bulb.
Most Knox County homes land between $900 and $2,500. What moves the number is foundation type and routing. A basement with an accessible interior chase and a straightforward attic run sits at the low end. A crawlspace needing a full sealed membrane, or a home where the pipe has to go around the outside to keep it out of living space, sits higher. Multiple foundation types under one roof, common in additions, sometimes need two suction points. Every quote we give is fixed and written before any work starts. See the full cost guide.
Basement or slab-on-grade: a core-drilled suction point through the slab, sealed at the penetration, with existing cracks and the sump lid sealed as part of the work. Crawlspace: a heavy sealed vapor barrier across the floor with suction drawn from beneath the membrane. This is sub-membrane depressurization, it works as well as the slab version, and it usually improves moisture and musty smells as a side effect. Mixed foundations: assessed individually, since a system that only treats half the footprint only fixes half the problem.
Most installs are done in a single day. You approve the pipe route in advance, because where the pipe runs is the part homeowners care about most and it is much easier to agree before than after. There is one small penetration in the slab or membrane, some drilling noise for part of the morning, and a fan mounted in the attic, garage or outside, never in occupied space. Afterward the fan runs continuously and produces a low hum comparable to a refrigerator.
A system that is installed but never verified is a guess. After the system has run long enough to stabilize, we place a monitor and run a full post-mitigation test, then give you the written result. That document is what you keep for your records, hand to a buyer, or show a lender.
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