Yes — even though Ohio doesn't require it. Roughly half of Ohio homes test above the EPA's 4.0 pCi/L action level (Ohio Department of Health radon program data), and radon risk is driven by the soil under a specific lot, not by whether a home is new or old. A newly built home on high-radon soil will test just as high as an older one next door unless it was built with radon-resistant features or gets mitigated after the fact.
Why "new" doesn't mean "radon-safe"
Radon gas comes from the natural breakdown of uranium in soil and rock, and it enters a building through gaps and openings in the foundation — cracks, sump pits, utility penetrations, even porous concrete block. None of that is affected by the home's age. Ohio's statewide average indoor radon reading is about 7.9 pCi/L, roughly double the national average, and that figure is a product of Ohio's underlying geology, not its housing stock. A brand-new slab poured over the same soil as an existing high-radon home carries the same underlying risk unless it was specifically built to manage it.
What it costs to build a radon system in vs. retrofit later
The EPA's radon-resistant new construction (RRNC) approach — a gravel layer, sealed vapor barrier, and vent pipe from sub-slab to roofline — is designed to be installed during the foundation stage, when the crew already has the slab open. Retrofitting the same system into a finished, occupied home means core-drilling through the slab, routing vent pipe through closets or exterior walls, sealing the penetration, and patching finished surfaces afterward. The physical work is the same; the context makes it dramatically more disruptive and typically more expensive after the fact.
Building code status in Ohio (verify before you assume)
Ohio recognizes RRNC as a defined standard in its administrative code but does not require builders to follow it, and there's no statewide law requiring a radon test or mitigation before a home sale or rental. That means the decision to include a radon system in a new build is currently left entirely to the builder and buyer — nothing forces the conversation to happen. If you're buying new construction, it's worth asking directly whether RRNC components were included in the spec, because the answer won't be obvious from a walkthrough.
What to do if your new home wasn't built with a system
A certified short-term radon test (minimum 48 hours under closed-building conditions, per EPA testing protocol) placed on the lowest lived-in level is the only reliable way to know your home's actual level. If the result comes back at or above 4.0 pCi/L, an active mitigation system — the same sub-slab depressurization design used in RRNC, but with an in-line fan added — typically reduces radon by 80-99%, often bringing a home below 2.0 pCi/L. See our radon testing guide for how testing works, or our mitigation systems overview for what an install involves in an existing home.
The bottom line for Ohio builders and buyers
Because RRNC is optional rather than code-mandated in Ohio, a radon system in a new home only happens if someone specifically asks for it. Given that installing the passive components during a build costs a fraction of a post-occupancy retrofit, and that roughly half of Ohio homes test above the action level regardless of age, asking for it during the build — or testing immediately after move-in if it wasn't included — is the lower-cost, lower-risk path either way.
Questions to ask your builder before the foundation is poured
If you're under contract on new construction, the window to add RRNC features closes once the slab is poured. Worth asking directly: Is a gravel sub-slab layer with a soil-gas collection point included? Is a sealed vapor barrier specified under the slab, or just standard visqueen without taped seams? Is a vent stack roughed in from the collection point to the roofline, or would that require cutting into finished space later? Is there a labeled junction box near the vent stack for a future fan? A builder unfamiliar with RRNC may not volunteer these details unprompted, even if the components themselves are inexpensive to add.
What if the home is already under construction or finished?
If framing or slab work is already complete, RRNC's foundation-stage components can no longer be added the easy way — at that point, a post-occupancy test followed by active mitigation (the same sub-slab depressurization approach, installed via a compact core-drilled entry point) is the standard path, and it's a well-established, routine service rather than a major renovation.
Reading a builder's spec sheet for radon language
Standard builder spec sheets rarely use the word "radon" at all, which is itself informative — if RRNC isn't mentioned, it usually isn't included. Some production builders bury it under a generic "environmental" or "energy efficiency" upgrade package rather than listing it as its own line item, so it's worth asking the sales representative directly rather than relying on the printed spec alone. A builder who has RRNC as a standard inclusion (not just an option) will typically say so proactively, since it's a selling point once a buyer understands what it means.
What this means for a whole subdivision, not just one lot
Radon risk is driven by geology, which means it doesn't respect lot lines — homes across an entire subdivision built on similar soil often share a similar radon risk profile, high or low. A production builder developing dozens of lots in the same area has more leverage to standardize RRNC into the base spec across every home than a single custom-build client negotiating one house at a time, since the marginal labor cost per home drops further with repetition. Buyers evaluating a new subdivision can reasonably ask whether the builder tested a sample of completed homes in earlier phases of the same development, since that data — where it exists — is a more direct signal for a specific area than statewide averages alone.
Weighing the upgrade against other buyer options
Builders who offer RRNC as a buyer-selectable option, rather than a standard inclusion, are essentially asking a homebuyer to weigh it against other structural and finish upgrades at the time of contract. Because the radon components are literally buried under the slab once poured, it's one of the few upgrades a buyer can't add later without disruption — unlike cabinet finishes or flooring, which remain changeable well after move-in. That's a meaningful point of difference worth factoring into the decision, separate from cost alone.
How this affects resale down the road
A documented radon system — whether passive or active — is generally viewed as a positive by future buyers and their agents, since it removes radon as an open question during a later sale's inspection period. A future buyer's own radon test still happens regardless (Rule of thumb in real estate: assume every serious buyer will test), but a home that already has RRNC or mitigation in place walks into that test with a real structural advantage over a comparable home that doesn't. Conversely, a home that tests high at resale with no system in place typically means either a price adjustment or a mitigation contingency gets negotiated into the deal — the same choice the original builder or buyer faced, just later and under more time pressure.
Where to go from here
If you're actively building or under contract, the conversation with your builder needs to happen now, before the foundation stage. If you already own a new-construction home without a system and haven't tested yet, that's the next step — see our radon testing guide for how an EPA-aligned test works in Ohio.
Key takeaways on getting a radon system for a new home
- A new radon system isn't guaranteed by a home's age — soil geology, not construction date, drives radon risk.
- Ohio's optional building-code status means a radon system only gets included in a new build if someone specifically requests it.
- A radon system installed during construction is dramatically less disruptive and typically less costly than one retrofitted afterward.
- If your new home doesn't have a radon system, a 48-hour EPA-aligned test tells you whether one is needed.
Questions about a specific lot, subdivision, or existing new-construction radon reading? Call Radon Eliminator at 216-480-9580.