Central Ohio radon retest schedule: 24 hours to every two years

A radon system just started humming in your basement, and somewhere in the paperwork is a line about retesting. Here is the whole calendar in one place, from the afternoon the fan first runs to the checkups that keep the number honest for as long as you own the house.

Day one: the baseline goes on paper

Activation day sets the reference point every later check is measured against. Ohio's radon mitigation standards (ORMS, the appendix to OAC 3701-69-08) require the start-up reading to be marked right on the manometer, and the system pressure to be given to you in writing. Before the job closes, the seals are checked, the pressure is verified, a backdraft test is run if the house has natural draft gas appliances, and a house with a sump pump gets confirmation that the pump still has power.

Take a phone photo of the manometer on day one, because that marked line is what every future glance at the pipe gets compared to. A liquid column still sitting where it was marked means the fan is pulling the way it was designed to. A column that has crept back toward level is a service call, and it can show up there long before a test would catch it. The is my system working FAQ covers what a changed reading means and what to check first.

Hour 24 to day 30: the verification test

ORMS also requires that you be told, in writing, when the first post-mitigation test belongs: no sooner than 24 hours after the fan is switched on, and no later than 30 days after. The first full day gives the pressure field under the slab time to settle. The 30-day ceiling keeps a weak spot from hiding through a whole season.

That test can be run by the mitigation specialist who designed the job or by an independent Ohio-licensed tester. Ohio's licensing rule adds a useful wrinkle: when the same licensee both tested or advised on a house and then mitigated it, the written contract has to say so, and it has to spell out the advantages of long-term testing and the value of a second opinion. If one company handled both your original test and the install, an independent verification test is the second opinion Ohio's own rule points you toward. A professional short-term test runs $150 to $300 here.

Wherever the verification device goes, put it where the pre-mitigation device sat. The Ohio measurement protocol places follow-up measurements in the same location as the first, so the before and after numbers describe the same air.

Year two, year four, and on from there

Once the verification number is filed, the standing rule is short. Retest a single-family home at least every two years, even when nothing about the house seems different. The Ohio Department of Health recommends a two-year cycle for single-family homes, EPA's consumer guide to radon reduction gives the same interval, and ORMS has the mitigator advise it at closeout.

Why keep testing a system that sounds fine? Fans wear out. EPA notes they may last five years or more and that manufacturer warranties tend not to run past five, so by the second or third checkup the fan is into the years when wear starts to show. Caulk ages, new hairline cracks open in a slab, and a basement that held boxes becomes a playroom. A test every other winter, with the house closed up and the device back in its usual spot, is the simplest way to know the system still earns its electricity. The testing frequency FAQ goes deeper on the two-year cycle.

Changes that restart the clock early

Some events make the last result stale no matter how recent it is. Retest after any of these, once the house is back to normal living:

• A significant renovation. ODH names it outright as a retest trigger, and EPA's Citizen's Guide advises testing before a major project such as finishing a basement and again once it is done.
• Moving daily life downstairs. A new basement bedroom in Westerville or a home office in a Dublin lower level means that floor is now where someone breathes for hours, and EPA says to retest on the level you start occupying.
• A replacement fan. Under ORMS, swapping a worn-out fan and leaving everything else unchanged does not count as altering the system, but new hardware still deserves a new number.
• Sump, waterproofing or foundation work. Interior drain tile, a new sump basin, crack repair and pier work all disturb the slab or the seals around it. Clay-rich glacial till drains slowly around Columbus, which is why interior drainage and sump jobs are familiar basement projects here. A sump lid lifted for service and left unsealed is an open door to the soil. The foundation work FAQ covers timing after that kind of job.
• Heating and ventilation changes. A new furnace or air handler, a whole-house fan, or a balanced ventilation system changes how the house breathes, and pressure differences are what move radon indoors.

If a renovation reroutes the pipe or relocates the fan, that is altering the system, and Ohio expects the altered system to meet ORMS before you trust a new number. Treat the finished project like a second day one: note the manometer, then test.

Apartment buildings, schools and offices: every five years

Larger buildings run on a slower clock. ODH recommends retesting multifamily buildings, schools and commercial buildings every five years, compared with every two for a single-family house, and after significant renovation in any case. An apartment owner in Clintonville or a small office landlord in Worthington can put the date on the same maintenance calendar that holds the roof and boiler checkups. A tenant in a unit with no test on record can ask the owner for the latest result.

The folder that makes every retest mean something

A retest number is only useful next to the numbers that came before it. ORMS requires a closeout package at the end of every mitigation job, and all of it belongs in one folder, paper or scanned, that stays with the house:

• the floor plan drawing showing the foundation, drains, entry points, pipe route, and where the fan and warning device sit
• pre-mitigation and post-mitigation test data
• contracts and warranties
• a description of the system, plus any deviations from ORMS
• operating and maintenance instructions, including what to do if the warning device goes off
• the installer's name, phone number and Ohio license number, and the phone number for the ODH radon program

Drop each retest report in as it arrives. Ohio test reports record exact device locations, start and stop times, and the license numbers involved, which is everything the next tester needs to repeat the measurement faithfully. When a buyer asks about radon years from now, that folder answers in minutes.

If your verification test is still ahead, or your newest result is more than two years old, schedule radon testing for the lowest lived-in level, or call or text us and we will help you sort out which retest trigger applies to your house.