Radon mitigation in Columbus. Installed this week.

Most Central Ohio basement and slab homes land between $1,200 and $2,400 for an active sub-slab system. Crawl spaces that need a sealed membrane run $1,800 to $3,500. A professional short-term test is $150 to $300.

The spread inside those ranges comes from the house, not the ZIP code. A 1990s Dublin or Pickerington slab with a clear path to the attic sits near the bottom. A Clintonville or Bexley basement with a patched floor, a sump, and walls that need extra sealing sits near the top, and a house that needs a second suction point can reach it. Ohio's mitigation standards also require items that belong in every price: a monitor or marked gauge, labels, an exterior fan hard-wired with its own outdoor disconnect, and a sealed sump cover that can still be lifted for pump service. Every Ohio proposal has to show the installation price and an estimate of what the system costs to run each year, so two quotes can be compared line for line. Our pricing guide by foundation type breaks the tiers down, and the calculator gives a starting range.

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A single-suction-point system in a basement or slab home is usually a one-day install. Crawl spaces that need a membrane, and houses with two foundation types, can take longer. The follow-up test then runs at least 48 hours.

The install day is only the middle of the sequence. Before it, Ohio's mitigation standards call for a visual inspection, a floor plan sketch, and a communication test wherever the material under the slab is unknown, so the suction point is chosen from data rather than habit. After it, the post-mitigation test has to begin no sooner than 24 hours and no later than 30 days after the fan is switched on, run by the specialist who installed the system or by an independent Ohio-licensed tester. Weather can nudge the calendar too: Ohio's testing rules bar short tests during severe storms or sustained winds of 30 mph or more, which can push a retest by a day or two in a blustery March. If a closing date is driving the schedule, say so on the first call and the plan gets built backward from it.

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Yes. Every Central Ohio county sits in EPA Radon Zone 1, and Franklin County's 16,142 pre-mitigation tests from 2008 to 2017 had an estimated mean of 9.5 pCi/L, more than twice the EPA action level of 4.0.

The county figure comes from an American Lung Association analysis of CDC tracking data, and it agrees with much older state work: the 1988-89 EPA and Ohio residential survey found 64 percent of 170 Franklin County homes above 4 pCi/L on short screening tests. The cause is geology. The Ohio Shale, the largest uranium source in the state, runs in a north-south band under Franklin and Delaware counties, and glaciers smeared shale and limestone debris across the region. The health stakes come from the EPA: about 21,000 US lung cancer deaths a year are tied to radon, roughly 2,900 of them among people who never smoked. None of that predicts a single house. Averages describe the region, and only a test tells you what your own basement is doing. See why Ohio radon runs high.

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Radon travels in the soil gas under your foundation. A heated house sits at slightly lower pressure than the ground, so it draws that gas in through the floor-wall joint, cracks, sumps, drains, pipe openings, crawl-space dirt, and joints in block or stone walls.

Central Ohio adds two local twists. First, most of the region is covered in glacial deposits, and the USGS found that the permeability of those deposits is the strongest control on how much radon reaches the surface: dense clay till slows it, while sand and gravel outwash along valleys like the Scioto and Olentangy lets it move freely. Second, the housing stock offers plenty of doors. A 1920s Clintonville basement may have mortared stone walls and a floor poured in sections, a postwar Whitehall ranch may sit over an open crawl, and a newer Hilliard split-level often has a slab and a crawl under one roof. Ohio's mitigation standards require the floor-wall joint, cracks, and utility openings to be sealed during an install, but sealing supports the fan; it never replaces it. See how a sump pit fits in.

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The Ohio Department of Health recommends retesting a single-family home every two years and after any significant renovation. Test sooner if you start using a lower level, replace the radon fan, or change the sump, waterproofing, or HVAC.

ODH sets a longer clock for bigger buildings: multifamily, school, and commercial buildings should be retested every five years or after significant renovation. In a house with a mitigation system, the first test after the install belongs inside Ohio's window of 24 hours to 30 days after the fan starts, and the installer is required to advise you in writing to retest at least every two years after that. Between tests, the gauge on the pipe is the everyday check. A two-year rhythm fits the climate zone 5A heating season well: pick a month between November and March, close the house the way the testing protocol asks, and keep each result with the install paperwork so you can compare year over year. The retest schedule lays out the full timeline.

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A short-term test, 48 hours to 90 days under Ohio's protocol, is the tool for a home sale and a first screening. A long-term test of more than 90 days shows the year-round average and is the better basis for a borderline decision.

Ohio's recommended strategy for a home that is not being sold starts with a short-term test in the lowest livable level, then adds a second short-term test or a long-term test when the first result lands between 4 and 8 pCi/L. For a sale, only the short route is practical, and Ohio requires at least 48 hours using either two side-by-side devices or a continuous monitor. Long-term devices, such as alpha-track detectors, suit a homeowner who wants the whole seasonal swing of a zone 5A year, and they need far less babysitting than a closed-house short test. Neither type is more official than the other; they answer different questions. The comparison page lays them side by side.

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Two separate things: a written workmanship warranty on the install, and the fan maker's warranty. Ohio also requires every proposal to state either a guarantee to bring the average below 4 pCi/L, with its conditions, or why no guarantee is offered.

The guarantee statement is the piece most homeowners never see spelled out elsewhere, and it comes from the Ohio Radon Mitigation Standards in the appendix to OAC 3701-69-08. Read its conditions; most are reasonable, such as keeping the fan running and the sump cover sealed. On the fan, the EPA notes that fans often last five years or more and that manufacturer warranties tend not to exceed five years, so expect at least one fan replacement over the life of the house. Ask whether the workmanship warranty transfers to a buyer if a sale is possible. Keep the closeout package, which Ohio requires to include the contract and warranties, the floor plan drawing, and the pre- and post-mitigation results. If the post-mitigation test misses the guaranteed level, the correction belongs under that guarantee. See what an Ohio proposal must include.

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A little. The fan runs around the clock on electricity, and the system can draw a small amount of heated or cooled air. Ohio requires every mitigation proposal to include an estimate of the annual operating cost, so you see the number before signing.

The EPA's guidance is plain: fan-powered systems are the most effective option and slightly increase the electric bill, by an amount that depends on the climate, the system, and the house. In a zone 5A Central Ohio winter the bigger variable is heat loss, and the sealing done during the install (floor-wall joint, cracks, the sump cover) limits how much warm basement air the fan can pull down through the slab. You can check the fan's draw yourself from the rating on its housing and your AEP Ohio rate. Never switch the fan off to save money; the EPA is explicit that it must run continuously for the system to work. If the operating estimate on a proposal looks high or oddly low, ask how it was calculated and which fan it assumes.

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