Radon Testing in Ault, Colorado | InspectandTest
Ault, the small farming and railroad town on the northern plains northeast of Greeley, sits squarely inside EPA Radon Zone 1, the agency’s highest-risk category, where the predicted average indoor radon level meets or exceeds the 4 pCi/L action threshold. Radon is a colorless, odorless radioactive gas produced by the natural decay of uranium in soil and rock, and it is the second-leading cause of lung cancer after smoking. The plains soils beneath Weld County carry enough uranium that elevated readings turn up in modest farm cottages and newer builds alike. This page explains how radon testing ault residents should plan, why the local picture demands it, and what a test costs. This summary reflects EPA and CDPHE guidance current as of 2026; consult a certified professional for testing decisions.
Part of our Radon Levels guide — start there for the full picture →
Radon testing in Ault: what to know
Radon testing measures the gas that has accumulated inside a home, reported in picocuries per liter (pCi/L). The EPA recommends taking action at or above 4 pCi/L, and because Ault lies in Zone 1, a meaningful share of local homes test at or above that line. Two houses on the same Ault block can read very differently depending on foundation cracks, soil contact, and how tightly the home is sealed against the long plains winter, so the only reliable way to know your number is to test.
Short-term tests run two to seven days and suit real-estate timelines; long-term tests of 90 days or more average out seasonal swings and give a fuller picture of year-round exposure. For the underlying science and the device types involved, our plain-language radon guide for Front Range homeowners walks through both approaches in detail.
Why levels vary so much house to house is worth understanding. Radon depends on the uranium content of the soil directly beneath a foundation, the number and size of slab cracks and openings, and how hard the home’s heating system pulls air through those gaps. Two similar single-story homes one lot apart on the Ault plains can read 2 pCi/L and 9 pCi/L for exactly these reasons. That variability is why a neighbor’s clean test tells you nothing about your own home, and why radon testing is always an individual-home decision rather than a town-wide assumption.
Radon also changes over time, so a single clean test years ago does not guarantee a clean home today. A century-old farmhouse settles and opens new cracks, a remodel changes airflow, and a new high-efficiency furnace alters the pressure that draws soil gas indoors. EPA guidance is to re-test every couple of years and after any major change to the home. For an Ault household that added a finished room or replaced an old furnace since the last test, a fresh measurement is the only way to know the current level.
Why Ault homes need radon testing
Geology is the driver. Radon comes from uranium decay in soil and rock, and the deep plains soils of Weld County release it readily. The DJ Basin oil-and-gas country surrounding Ault sits on the same uranium-bearing formations that feed radon into homes, and the flat agricultural ground means most houses sit directly on or just above soil that is steadily generating the gas.
Climate concentrates it. Ault winters are cold and the wind off the plains is relentless, so homes stay sealed for months while furnaces create slight negative pressure that pulls soil gas indoors through slab cracks, crawl-space gaps, and around utility penetrations. The town’s older grain-elevator-era cottages often have stone or block foundations and dirt or partial basements that breathe radon directly, while newer infill homes are built tight for energy efficiency and trap the gas once it enters.
The mix of housing eras makes a uniform assumption impossible. A 1910s farmhouse with a fieldstone cellar and a 2010s build on a slab face the same Zone 1 soil but channel radon differently, and the only way to separate them is a measurement in each. Because so many Ault parcels are rural with well water and septic systems, the lowest livable level is frequently a basement or ground-floor room where a family spends real time, which is exactly the worst-case location for exposure.
What an Ault radon test covers
A professional test places a calibrated continuous radon monitor or a passive device in the lowest livable level of the home, usually a basement or ground-floor room, under closed-house conditions. The tester documents the placement and the closed-house window so the result holds up if it later feeds a real-estate negotiation.
Closed-house conditions
For at least 12 hours before and throughout a short-term test, windows and exterior doors stay closed except for normal entry. This keeps a windy plains afternoon from artificially lowering the reading. If a test comes back at or above 4 pCi/L, the next step is mitigation, which we cover in our guide to radon mitigation in Ault.
Continuous monitors versus passive kits
A continuous radon monitor logs hourly readings, so it can show whether a window was opened mid-test or whether levels spiked overnight, evidence that protects a buyer from a tampered result. Passive devices such as charcoal canisters average exposure and mail to a lab at lower cost. For an Ault home sale, the continuous monitor’s tamper detection and hour-by-hour record make it the preferred tool. For a homeowner’s own long-term picture, a passive kit left in place for months gives a more representative annual average.
Evaporative or swamp coolers, common on the plains for summer cooling, also matter to the test. Because they pull large volumes of outside air through the house, they can dilute a reading taken while they run. A careful tester schedules the closed-house test for a window when the cooler is off so the result reflects the home’s true winter-sealed condition rather than a summer airflow that no family lives with year-round.
Radon testing cost in Ault
A professional short-term radon test in the broader Greeley and Weld County market typically runs about $135 to $250. A do-it-yourself kit costs roughly $15 to $40 plus lab fees, and CDPHE periodically offers discounted kits to Colorado residents. Bundled into a pre-purchase home inspection, radon testing often adds just $100 to $175 instead of a separate trip charge to a town as small as Ault.
Long-term kits sit at the low end on price but tie up months. For a transaction, the documented short-term professional test is standard because it fits inspection deadlines and produces a defensible closed-house result a buyer’s agent can rely on.
Weigh the cost against the protection. The EPA links thousands of lung-cancer deaths a year to radon, and Ault’s Zone 1 status puts local exposure risk among the highest in the state. A $200 test that catches a 7 pCi/L basement reading lets a family install a roughly $1,500 mitigation system and cut exposure by 90 percent or more. Skipping the test leaves the risk invisible for as long as the family lives there, which in a stable farm town can be decades.
The choice between a DIY kit and a professional test usually comes down to purpose. For a homeowner’s own awareness, an inexpensive CDPHE-discounted kit is a reasonable starting point. For a real-estate transaction, the professional continuous-monitor test is the standard because its tamper detection, documented placement, and defensible result hold up when the number drives a mitigation request.
Where to place the device
Placement determines whether the result reflects real exposure. The device belongs in the lowest level that is or could become living space, set about 20 inches or more above the floor, away from exterior walls, drafts, direct sun, and any sump or floor drain. In a typical Ault home that means the basement family room or a ground-floor bedroom rather than an unfinished mechanical corner or a dirt cellar. Testing a space no one occupies understates the exposure a family actually experiences.
Conditions during the test matter as much as location. A short-term test needs closed-house conditions for at least 12 hours before and throughout, so windows and exterior doors stay shut except for normal entry, and any evaporative cooler stays off. A professional follows EPA placement and closed-house protocol precisely, because a result that drives a mitigation decision or a purchase negotiation has to be defensible.
Colorado regulations and disclosure
Colorado requires radon disclosure in residential real-estate transactions, and the Seller’s Property Disclosure asks sellers to report known radon results and any existing mitigation system. CDPHE runs the state radon program, references the 4 pCi/L EPA action level, and offers discounted kits to residents. Colorado does not license home inspectors, so for any test tied to a sale, confirm the tester follows recognized national measurement protocols rather than assuming a license guarantees competence.
Disclosure shapes negotiations both ways. A seller who has tested and mitigated can offer a clean post-mitigation result as reassurance, while a seller who has never tested leaves the buyer to discover the number during the contingency, often resulting in a mitigation credit. Buyers in Zone 1 Ault should not waive radon testing to sweeten an offer; the modest cost of the test and fix is small against the long-term health stakes of an untreated basement. Ault sits within the same county radon picture documented across our Weld County radon testing hub.
Neighborhoods and areas served
Radon turns up across Ault regardless of where a home sits: the older cottages near the historic grain-elevator core and the original townsite, the newer infill and edge-of-town builds, and the rural well-and-septic parcels scattered across the surrounding farmland. Service typically extends to adjacent Eaton, Pierce, Nunn, and nearby Greeley, all within the same Zone 1 plains footprint where elevated readings are common. Homeowners comparing nearby options can also review our radon testing in Eaton page.
Because the plains geology that drives radon is consistent across this corner of Weld County, the Zone 1 designation does not stop at the Ault town limits. A century-old house on a quarter-acre in town and a new build on a rural acreage face the same uranium-bearing soil. Wherever the home sits, treating radon as a default test rather than an optional add-on reflects the reality that the entire area sits in the highest EPA risk zone.
How to choose an Ault radon testing provider
Ask whether the provider uses a calibrated continuous radon monitor and follows EPA or AARST protocols. A good tester documents closed-house conditions, device placement, and test duration so the result stands up in a sale. Bundling radon with a full home inspection is efficient and gives buyers one coordinated report on both the structure and the soil-gas risk, which matters for the older farm homes common around Ault.
Confirm the monitor’s calibration is current and, for a purchase, ask the provider to place and retrieve the device themselves rather than handing you a kit, since a tester-administered continuous monitor carries far more weight in a negotiation. If a result comes back borderline, between 2 and 4 pCi/L, a competent provider explains your options, including a follow-up long-term test, rather than pushing an unnecessary mitigation sale.
For homeowners not in a transaction, a CDPHE discounted long-term test kit is a low-cost way to get a representative annual average and a reasonable first step before bringing in a professional. If that kit comes back at or near the action level, a professional follow-up confirms the result with calibrated equipment before you commit to mitigation. Either path beats not testing at all, since every Ault home sits in Zone 1 and the only way to know your number is to measure it.
References
- Radon risk and EPA zone maps — U.S. Environmental Protection Agency
- Colorado radon program and kits — Colorado Department of Public Health and Environment
- Radon and lung cancer — Centers for Disease Control and Prevention
Frequently asked questions
Is Ault in a high radon zone?
Yes. Ault sits in EPA Radon Zone 1, the highest-risk category, within Weld County. The plains soils release uranium-derived radon readily, so every home, especially those with basements, should be tested.
What radon level requires action in Ault?
The EPA action level is 4 pCi/L. At or above that reading, EPA and CDPHE recommend mitigation. Levels between 2 and 4 pCi/L are still worth considering for reduction.
How much does a radon test cost in Ault?
A professional short-term test typically runs $135 to $250, while DIY kits cost about $15 to $40 plus lab fees. CDPHE periodically offers discounted kits to Colorado residents.
Do evaporative coolers affect an Ault radon test?
Yes. Swamp coolers pull large volumes of outside air through the house and can dilute a reading. A careful tester runs the closed-house test with the cooler off so the result reflects the home's sealed winter condition.
Can two neighboring Ault homes have different radon levels?
Yes. Radon depends on soil uranium content, foundation cracks, and how the home is heated and sealed, so similar homes a lot apart can read very differently. A neighbor's clean test does not predict yours.
Every Ault home sits in EPA Zone 1, so radon testing is basic due diligence, not optional. To connect with a vetted local tester before your purchase deadline or this heating season, get in touch through our contact page.
Test your home for radon
Radon is invisible and odorless, so a test is the only way to know your level. A short-term kit gives a first reading in days; a digital monitor tracks it over time.
| Product | Why | Buy |
|---|---|---|
 AirChek Charcoal Radon Test Kit | Lab fee usually included; EPA short-term protocol. | Amazon — $21.95 |
 First Alert RD1 Radon Test Kit | Widely stocked; 48-hour charcoal test. | Amazon — $16.98 |
 Airthings Corentium Home | Digital monitor with a long-term average. | Amazon — $147.14 |