Basement projects are everywhere in Knox County right now. A bonus room for the kids, a guest suite for the in-laws, a home office that finally has a door. The lower level of a house on a Farragut, Fountain City or West Knoxville hillside is often the biggest unused space the family owns. It is also the part of the house closest to the ground, which makes it the part where radon matters most.
Radon is a radioactive gas that forms naturally in rock and soil. It moves up through the ground and enters a house through the slab, cracks, joints, floor drains and sump pits. East Tennessee has a well known history of elevated radon, and our radon levels page explains what we see locally. The basement collects the most of it, and once you turn that space into a bedroom or a den, people are breathing it for hours a day.
A radon test is inexpensive and takes a few days. Do it before the project begins, under normal closed house conditions, so you have a clean baseline. A test run during active construction, with the doors open and dust in the air, does not give a reliable number. Our radon testing page explains how a test works and how to read the result.
If the number is low, you have peace of mind and a record to keep with your permit paperwork. If it is high, you have found out at the cheapest possible moment.
A mitigation system pulls air from beneath the slab and sends it through a pipe to a fan and out above the roofline. When the walls are open and the ceiling is not yet closed, running that pipe is straightforward. After the drywall is up and the trim is painted, the same pipe may have to go through a closet, a chase or a boxed in corner, and the finish work around it has to be repaired. If you need a system, we want to meet your contractor before framing so that space is left where it is needed. Read our mitigation page for how a system works and the cost guide for what to budget.
Crawl space homes with a finished lower level or an addition are a related case, and the approach is different, so tell us what you have.
Even with a low reading, some homeowners ask for a passive rough in, which is a capped pipe from under the slab up through the house, without a fan. It adds little to the project, and if a later test comes back high, adding a fan is a short visit instead of a rebuild. Radon levels shift over the years, so a pipe in the wall is a reasonable precaution on a hillside lot.
If you sell later, a buyer's agent will ask about radon on the lower level, particularly if it is finished living space. Having a test result and any system documentation on hand speeds up the deal. Our page on the Tennessee radon disclosure explains what sellers should know about disclosure.
Before work starts: test the lowest level with the house closed up normally.
Before framing: if the result is elevated, walk the space with us and your contractor to choose the pipe route and fan location.
After the finishes are done: test the finished space again, since that is where people will live.
Call (865) 563-8112 with your address and a short description of the plans. We will set up the test and explain the result in plain language.
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Call (865) 563-8112