Radon Testing and Mitigation for Salt Lake City's Older Basements

Why an older Salt Lake City foundation has so many ways in

Much of Salt Lake City was built long before anyone was thinking about soil gas. Across Salt Lake County you will find basements with stone or block foundation walls, mortar joints that have loosened over decades, a floor drain in one corner, and a slab poured in sections that have since shifted apart. Radon is a naturally occurring gas that rises out of the ground, and every one of those features is a possible way in. None of them are defects in the ordinary sense. They are simply the details of an older house, and together they add up to a foundation with many small openings rather than one obvious hole.

That matters because radon is odorless and colorless. You cannot walk a basement and see it, and nobody in the house notices anything different when it is present. Radon exposure produces no symptoms, which is exactly why a measurement is the only way to find out what your house is doing. It also means a neighbor's result is not a stand-in for yours. Two homes on the same block, built the same year by the same builder, can read very differently depending on the soil, how the foundation settled, and how each house is heated and ventilated. The only number that describes your home is measured in your home.

Sealing helps, but it is not the mitigation system

It is tempting to look at a cracked slab or an open floor drain and assume caulk and patching will settle the matter. Sealing is genuinely useful, and a good contractor does it as part of the work. On its own, though, it rarely holds. An older foundation has more entry paths than anyone can find, including gaps behind finished walls, the opening around a sump pit, and the hollow cores of block walls themselves. Close five and the soil gas uses the sixth. Sealing reduces the number of leaks a system has to overcome. It is not a substitute for the system.

The standard fix is sub-slab depressurization. A pipe is set through the slab, a fan draws soil gas from the ground beneath the floor, and that gas is vented above the roofline instead of drifting up into the basement. Because the fan holds the space under the slab at slightly lower pressure than the room above it, the small openings that worried you stop pulling gas inward. That is the reason sealing supports the system rather than replacing it. After installation the house is re-tested, because the follow-up measurement is the only evidence that the design did what it was meant to do.

Testing an older basement, then deciding

Start with a test, not a decision. A short-term test gives you a quick reading and is often the first step, particularly when a sale is involved. A long-term test runs for a longer stretch and better reflects an annual average, because levels move with weather, season, and how the house is operated, from open windows in September to the furnace running in January. Neither is the wrong test; they answer slightly different questions. The EPA publishes an action level, and the Utah Department of Environmental Quality publishes state guidance and radon maps, so check those sources for current figures before you interpret a result.

If your reading points toward mitigation, the next step is a look at the actual basement. A contractor will want to see where the slab can be penetrated, whether there is a sump to work with, how the foundation walls are built, and where a pipe can run without cutting through living space. Older Salt Lake City houses often offer a straightforward route through an unfinished corner. Call 801-644-9000 and we will connect you with radon contractors working in Salt Lake County who can look at your foundation and quote the work. Test first, then decide, is the order that keeps the choice an informed one.

Questions from Salt Lake City homeowners