Radon in a Utah Basement Apartment: What to Test Before You Rent, Finish, or Move In
Radon is a real issue in Utah basement apartments — the Utah Department of Environmental Quality (DEQ) estimates about 1 in 3 Utah homes test above the EPA action level, and radon levels typically run highest in a home's lowest level: exactly where a basement apartment sits. It's also fixable: a test costs $30 or less, and mitigation typically runs around $2,000 (a planning estimate — site conditions change it). This guide is for Utah renters, landlords, and homeowners planning a basement apartment. (Planning a detached unit? Radon still matters — see our detached ADU guide.)
Last verified: July 2026
About this guide. Utah ADU Builders is an independent, Utah-focused ADU planning, feasibility, and builder-matching resource — not a government office, law firm, health agency, radon mitigation company, or licensed contractor. We may receive compensation when homeowners request estimates or get connected with local professionals through our feasibility funnel. That compensation doesn't change the numbers, rules, or risks explained on this page. Nothing here is legal or medical advice.
What we verified (July 2026): Utah radon statistics, testing protocol, and mitigation guidance from the Utah DEQ; action levels and health data from the U.S. EPA; landlord, licensing, and building-code context from the Utah Department of Health and Human Services' Radon in Utah report; Utah's internal ADU framework via the Utah Property Rights Ombudsman; and the current HOA radon statute and the 2026 session's radon bill in the Utah Legislature's records. Full source list at the end of this page.
Your situation, your next step
| Your situation | Bottom line | Next step |
|---|---|---|
| Planning to finish a basement into an apartment | Test before major finishes or occupancy | Put radon testing in the feasibility phase — it's a $30-or-less step |
| Already renting out a basement apartment | You need a documented, recent result | Test now; fix if high; retest every two years |
| Renting (or about to rent) a basement apartment | Ask for recent results — or test it yourself | If it's high, notify the owner in writing |
| Result is below 2.0 pCi/L | Lower concern, not zero risk | Keep the record; retest after big changes |
| Result is 2.0–3.9 pCi/L | Below the action level, still worth watching | Consider a long-term test if someone lives down there |
| Result is 4.0 pCi/L or higher | Action recommended — this is fixable | Follow-up test, then mitigation bids |
| A mitigation system already exists | A system isn't proof of current low levels | Check the manometer; retest |
Planning a basement apartment? Radon is one feasibility input among many — egress, moisture, parking, and your city's rules matter just as much. Before you spend on finishes:
Check ADU FeasibilityA feasibility check is planning help — not a permit approval, legal opinion, health diagnosis, or construction guarantee.
Is radon actually a problem in Utah basement apartments?
Yes — several times over the national rate. The Utah DEQ estimates about 1 in 3 Utah homes have radon above the EPA action level of 4.0 pCi/L, compared with the EPA's national estimate of roughly 1 in 15, thanks to the uranium-bearing soil and rock under much of the state, including the Wasatch Front. Radon is a colorless, odorless radioactive gas, so the only way to know your level is to test — and the lowest level of a home is typically where it concentrates.
The more sobering number is how few people check: in the most recent state health survey to ask the question, about four in five Utahns said their home had never been tested for radon (Utah Department of Health and Human Services, 2016 survey data).
Why the basement usually reads highest
Radon comes from the soil, and the basement sits directly on the source. The gas moves into a home through slab cracks, floor-wall joints, sump pits, utility penetrations, and crawl spaces, and because indoor air pressure is usually lower than the pressure in the soil, the house gently pulls soil gas inward. Levels are typically highest in the lowest level and dilute as air rises through the home — which is why the Utah DEQ and the EPA both point testing at the lowest lived-in level.
That's the whole reason this page exists: a basement apartment means someone sleeps in the home's typically highest-radon level roughly eight hours a night, every night. The same house that's fine for a family living upstairs deserves a fresh look when the basement becomes someone's bedroom.
A few factors make testing especially worth prioritizing:
- ▸Someone sleeps (or will sleep) in the basement full-time
- ▸The basement was recently finished or sealed up — airflow has changed
- ▸There's a sump pit, crawl space, visible slab cracks, or utility penetrations
- ▸There's no documented test on record, or the last one predates a remodel
- ▸A mitigation system exists but hasn't been retested in years
Why your neighbor's result doesn't prove yours
Utah's own health department cautions that radon test data isn't systematic — results reflect which homes happened to test — and that the individual house or building is the biggest factor in indoor levels, more than the geology alone. Two homes side by side can produce very different numbers. The DEQ publishes median radon levels by ZIP code if you want a sense of your area, but a ZIP median is context, not a substitute for testing your actual basement.
What radon level is unsafe in a basement apartment?
The number to know is 4.0 pCi/L (picocuries per liter, the standard unit for radon in air). At or above 4.0, the EPA and Utah DEQ recommend taking action — usually a follow-up test, then mitigation. Between 2.0 and 4.0, the EPA suggests considering a fix, because there is no known fully safe level of radon.
Why the concern is real: the EPA identifies radon as the second-leading cause of lung cancer in the United States, the leading cause among people who have never smoked, and a factor in an estimated 21,000 deaths per year. Risk builds with long-term exposure — years, not weekends — which is exactly why a full-time basement bedroom raises the stakes compared with a laundry room nobody lingers in. And per Utah health officials, the risk of developing lung cancer is about 10 times higher for people who smoke and live in a home with high radon than from either factor alone.
| Test result | What it means | Practical next step |
|---|---|---|
| Below 2.0 pCi/L | Lower concern, not zero risk | Keep the record; retest after major changes or when the basement becomes occupied |
| 2.0–3.9 pCi/L | Below the action level, but measurable | Consider a long-term test if someone lives down there full-time |
| 4.0 pCi/L or higher | EPA/Utah action level reached | Run a follow-up test; if confirmed, get mitigation bids |
| 8.0 pCi/L or higher (double the action level) | Treat follow-up as urgent | Do a prompt second short-term test and line up bids |
| Post-mitigation result | Confirms whether the system works | Save the documentation; keep retesting on a schedule |
How do you test a basement apartment for radon?
Place a test in the lowest lived-in level — the basement apartment's living area — follow the closed-house instructions, and mail it to the lab. The Utah DEQ's short-term protocol runs 48–72 hours for common kits with windows and doors kept closed (normal entry and exit is fine) before and during the test. It's one of the cheapest pieces of due diligence in all of housing.
Where to get a kit
The Utah DEQ sells low-cost mail-in kits online, and hardware stores carry kits for roughly $15–$30, lab analysis usually included. As of early 2026, Utahns could also request a free kit through UtahRadon.org, a Utah radon-awareness nonprofit — availability and pricing change, so check current options. Continuous digital monitors cost more but track levels year-round — useful once a tenant is living downstairs.
Placement rules that actually matter:
- Put it in the basement living area — a bedroom or main room, at breathing height where practical
- Not in a kitchen, bathroom, closet, crawl space, or unused utility room
- Keep closed-house conditions per the kit instructions
- Note the date, location, and result, and keep the lab report
Short-term test
48–72 hours for common kits. Fast first answer — useful before occupancy or when you need a number quickly.
Long-term test
More than 90 days. Captures seasonal swings and better reflects the year-round average — ideal when someone lives in the space.
What happens if the basement tests high?
A high result is a planning problem, not a project-killer. The standard sequence is a follow-up test to confirm, then a mitigation system — and the DEQ notes most homes can be brought to 2.0 pCi/L or below. What a high result should change is your order of operations: handle mitigation before a tenant moves in, and before new finishes make the work more disruptive.
The standard fix is active sub-slab depressurization: a sealed pipe through the basement slab connected to a continuously running fan that pulls soil gas from under the foundation and vents it above the roofline — intercepting radon before it enters the living space.
Two credentials matter when hiring in Utah
- 1.State licensing (S354): Anyone who installs or repairs a radon mitigation system in Utah must hold the state's S354 Radon Mitigation Contractor license, per the Utah Department of Health and Human Services.
- 2.National certification (NRPP or NRSB): National Radon Proficiency Program or National Radon Safety Board certification — which is what the DEQ's public mitigator lists are built on. The DEQ doesn't endorse individual companies, and neither do we.
The DEQ's homeowner playbook:
- 1Get at least three bids from qualified mitigators
- 2Get a written guarantee of the radon level the system will achieve — at or below 4.0 pCi/L, and ideally lower
- 3Retest after the system has run for 24 hours
- 4Check the manometer — the small U-shaped gauge on the pipe — periodically to confirm the fan is pulling
How much does radon mitigation cost in Utah?
Plan on roughly $2,000 for a typical Utah home — that's the Utah DEQ's own planning figure, and Utah installers quoted $1,800–$2,300 in early-2026 reporting. The DEQ also pegs ongoing costs at about $8–$10 per month in electricity, with the fan typically needing replacement after around 15 years. Treat all of these as estimates, not bids: slab conditions, crawl spaces, finished ceilings, pipe routing, and homes needing multiple suction points can push costs higher.
| Line item | Planning note (estimates; get current bids) |
|---|---|
| DIY short-term test kit | Roughly $15–$30 retail with lab analysis included; low-cost DEQ kits and, as of early 2026, free kits via UtahRadon.org |
| Professional test | Useful when you need defensible documentation — real estate, tenant disputes |
| Mitigation system | ~$2,000 per Utah DEQ; $1,800–$2,300 in recent Utah installer quotes; complex sites cost more |
| Rough-in during construction | Cheapest window to add radon piping — build it in before drywall |
| Electricity | ~$8–$10/month per Utah DEQ |
| Fan replacement | Roughly every 15 years per Utah DEQ |
| Post-mitigation retest | Build it into the job — the DEQ says test after the system runs 24 hours |
| Finish repair | The hidden cost of mitigating after the basement is finished |
Against a full basement-conversion budget, mitigation is usually one of the smallest line items on the sheet — the expensive version of this problem is only ever the one you discover late. For how radon fits into the bigger numbers, see our Utah ADU cost guide.
Does Utah require landlords to test for or disclose radon?
No. Utah's own health department states it plainly: there is no legal requirement for rental property owners to test rental property for radon or to install a mitigation system if elevated levels are found (Utah DHHS, Radon in Utah). We also checked the 2026 legislative session: its one radon bill, H.B. 563 — which addressed certification for radon mitigation companies, not landlord testing — did not become law (Utah Legislature, H.B. 563, 2026 General Session). That doesn't make radon a non-issue for landlords. It makes it a judgment call — and the judgment isn't hard.
On the broader legal backdrop: Utah's Fit Premises Act requires rental housing to be "fit for human habitation" and kept "safe, sanitary," but state health officials note the Act contains no radon-specific language and that it's unclear how radon would be interpreted under it — while also observing that radon is plainly the kind of condition that affects health. If you're in an actual dispute, on either side, talk to a Utah attorney. This page is general information, not legal advice.
What Utah law does say about radon
Radon shows up in Utah real estate law at the point of sale: Utah doesn't require radon testing when a home changes hands (Utah DHHS), but the seller disclosure process asks whether the seller knows of hazardous conditions "such as Radon gas in house or well," answered to the seller's current actual knowledge (Utah DEQ) — and since 2014, radon has had its own line on the Utah Association of Realtors' buyer due-diligence checklist. The pattern some owners fall into — never testing so they can honestly answer "don't know" — protects the paperwork, not the person sleeping downstairs.
Two more Utah-specific provisions worth knowing: HOAs and condo associations can't prohibit industry-standard radon mitigation modifications (more on that below), and Utah's building code sets a quality bar for radon work in new construction — when passive radon controls, or portions of them, are voluntarily installed, state code requires them to comply with Appendix F of the International Residential Code (Utah Code §15A-3-206). Note the word voluntarily: Utah has not adopted Appendix F as a statewide standard, so radon systems aren't mandated in new homes (Utah DHHS).
Why smart landlords test anyway
Renting a Utah basement apartment? Here's what you can do
Ask the owner for recent results first — and if there aren't any, you can test the space you live in yourself. A passive kit is a small, non-invasive device that sits on a shelf; follow the kit instructions, and don't alter the property or test shared spaces without asking. If the result comes back at 4.0 pCi/L or higher, put it in writing: fixing the building is the owner's call to authorize, but a documented lab number changes the conversation.
Questions worth asking before you sign a basement lease:
- ▸Has this unit been tested for radon, and when?
- ▸Was the test done in the basement living area?
- ▸What was the result, in pCi/L?
- ▸Is there a mitigation system — and has the unit been retested since it was installed?
If your test comes back high
A communication template, not a legal document.
Converting your basement into an apartment? Test before you build
The cheapest radon fix you'll ever get is the one designed in before the drywall goes up. Converting a basement changes how radon behaves in the space — new HVAC, tighter air sealing, an egress window, exhaust fans, and a person now breathing down there all night — so the sequence matters as much as the test itself.
The basement apartment radon sequence:
- 1Test the unfinished basement first. A $30-or-less baseline before design decisions.
- 2Design with the result. At or near 4.0, plan the mitigation route now — pipe path, fan location, electrical — while walls are still theoretical.
- 3Install or rough-in during construction. This is the cheap window. Utah code requires voluntarily installed passive radon controls, or portions of them, to comply with IRC Appendix F (Utah Code §15A-3-206) — a rough-in is exactly such a portion, so have it built to that standard.
- 4Retest after finish work, under closed-house conditions, before anyone moves in. The "before" number is not automatically the "after" number once the space is sealed, conditioned, and occupied.
- 5Retest every two years — and after any remodel or HVAC change — for as long as someone lives down there.
A quick word on where this fits legally. In Utah, an accessory dwelling unit (ADU) is a second, self-contained living unit on a single-family lot; a basement apartment is often an internal ADU — a unit created inside an owner-occupied single-family home, within its existing footprint, rented for 30 days or longer. Not every basement apartment qualifies, though: classification depends on the property type, whether the owner lives in the home, whether the unit sits within the original footprint, rental duration, and your city's ordinance and permit status.
Under Utah Code §10-21-303 (and §17-80-303 for counties), internal ADUs are a permitted use in residential zones statewide, per the Utah Property Rights Ombudsman — but cities can still apply real conditions, including minimum lot sizes, parking requirements, rental permits or licenses, and short-term rental prohibitions, and every internal ADU must meet building, health, and fire codes. Radon isn't on the permit checklist, but "health" is the point of the whole exercise — and the rest of the rules vary meaningfully by city. Our Utah basement apartment and internal ADU guide covers that side in full.
And the honest caveat: an ADU is not automatically a smart project just because Utah has become more ADU-friendly. The right call depends on your lot, your city, your utilities, your budget, and what the space is for. Occasionally a radon test, a moisture problem, or an egress cost is the early signal that a garage conversion or detached unit — or waiting — is the better path. Better to learn that for $30 than after you've spent serious money on finishes.
Not sure the basement is still the right path?
Feasibility first, then costs, then builder conversations.
See What Kind of ADU Your Property May SupportDoes a basement apartment permit mean radon is handled?
No — don't assume it. There's no statewide radon-testing step in Utah's permitting framework, and Utah hasn't adopted the IRC's radon-control appendix as a standard (Utah DHHS) — so an approved basement apartment isn't radon-checked by default. Treat radon as your own line item: test the space directly instead of assuming an approval covered it.
The reverse is also true, and worth saying plainly: a good radon number doesn't make the apartment legal. Permits, egress, fire separation, parking, and your city's internal ADU rules are their own track. Run both.
Can an HOA block a radon mitigation system in Utah?
Generally, no — Utah law bars HOAs and condominium associations from prohibiting radon mitigation modifications that are consistent with industry standards (Utah Code §§57-8-8.1 and 57-8a-218, enacted via H.B. 104 in 2024). The protection comes with sensible conditions: the work can't violate a local land-use ordinance or a building, health, or fire code, and the association may require proof of elevated radon and proof that a licensed person will do the work.
Associations can still apply placement and external-appearance rules — but under the statute, those rules can't be used against your project if they would unreasonably interfere with the system's functionality or add more than 40% of the system's original cost to the installation. In practice: expect design review on routing and looks, bring your test result and your licensed installer's info, and know that the system itself can't be banned.
Related and useful: under Utah's HOA statutes and ADU framework, an association also can't prohibit a code-compliant internal ADU. Neither provision exempts you from your city's rules — they just take "the HOA said no" off the table.
Does radon affect renting it out — or selling — later?
Handled properly, radon becomes an asset, not a liability. Utah doesn't require radon testing at the point of sale (Utah DHHS), but the seller disclosure form asks about known hazardous conditions including radon to your current actual knowledge (Utah DEQ), buyer due-diligence checklists now call it out specifically, and careful tenants ask about it up front. A dated lab report and a documented, working mitigation system answer the question cleanly for all of them. The owners who end up in awkward positions are almost always the ones with no paper trail at all.
Keep a simple file:
- Every test result with dates and locations
- The mitigation contract and guarantee
- The post-installation retest
- Your two-year retest record
It takes minutes and it's exactly what a careful tenant or buyer's inspector will ask for.
Utah basement apartment radon checklist
Use this before you rent out, finish, or move into a Utah basement apartment. It exists to keep radon from becoming the expensive afterthought in the plan.
ABefore occupancy or finishes
- Test the basement living area (lowest lived-in level) under closed-house conditions, per the kit instructions
- Save the result: date, location, lab, pCi/L
- If the result is 4.0 pCi/L or higher, run a follow-up test to confirm
- If confirmed, get three bids from mitigators who hold Utah's S354 radon mitigation contractor license and NRPP or NRSB certification, with a written performance guarantee
- If you're mid-construction, set the pipe route, fan location, and electrical before drywall — built to IRC Appendix F standards
- Retest after mitigation (once the system has run 24 hours) and after finish work, before anyone moves in
- Separately verify your city's basement apartment rules: zoning eligibility, owner occupancy, parking, rental licensing, egress, fire separation
BOngoing, once someone lives downstairs
- Glance at the manometer now and then — the fan should be pulling
- Retest at least every two years, and after any remodel or HVAC change
- Keep the whole paper trail for tenants, buyers, and future you
The permits, city rules, and cost side of that checklist is exactly what a feasibility review is for.
Understand what your property supports before you request quotes.
Request a Utah ADU Feasibility ReviewFrequently asked questions
Sources
- 1.Utah Department of Environmental Quality — Radon Program (statewide prevalence, action level, test kits, certified mitigator lists): deq.utah.gov
- 2.Utah DEQ — How to Test Your Home for Radon (placement, closed-house conditions, 48–72 hour protocol, retest triggers): deq.utah.gov
- 3.Utah DEQ — High Radon Levels? What's Next (follow-up testing, mitigation steps, ~$2,000 cost figure, operating costs, three bids, written guarantee, 24-hour retest, manometer): deq.utah.gov
- 4.Utah DEQ — Radon and Real Estate Transactions in Utah (seller disclosure question and "current actual knowledge" standard): deq.utah.gov
- 5.Utah Department of Health and Human Services — Radon in Utah report, February 2024 (no landlord testing/mitigation requirement; Fit Premises Act; S354 licensing; IRC Appendix F; 2016 BRFSS survey; smoking-plus-radon risk): ibis.utah.gov
- 6.U.S. EPA — A Radon Guide for Tenants (renter testing, written notice to owners): epa.gov
- 7.U.S. EPA — Radon (action level, national ~1 in 15 estimate, health risk estimates): epa.gov
- 8.Utah Property Rights Ombudsman — Accessory Dwellings (internal ADU definition, Utah Code §§10-21-303 / 17-80-303, permitted-use framework, allowed local restrictions, building/health/fire-code compliance, HOA provisions): commerce.utah.gov
- 9.Utah Code §§57-8-8.1 and 57-8a-218 — HOA/condo radon-mitigation provisions (enacted via H.B. 104, 2024; current text effective May 2026): le.utah.gov
- 10.Utah Code §15A-3-206 — Statewide amendments to the IRC (voluntarily installed passive radon controls must comply with IRC Appendix F): le.utah.gov
- 11.Utah Legislature — H.B. 563 (2026 General Session), Radon Amendments (mitigation-industry certification bill; did not become law): le.utah.gov
- 12.Utah DHHS IBIS — Radon health indicator report (test-data limitations, home-to-home variability): ibis.utah.gov
- 13.UtahRadon.org — Utah radon-awareness nonprofit (free test kit availability as of early 2026)
- 14.KSL-TV, February 2026 — Utah radon reporting (installer mitigation quotes of $1,800–$2,300)
This page is general information for Utah homeowners and renters, not legal, medical, engineering, or financial advice. Rules vary by city and change over time; verify current requirements for your property before building or signing a lease.