When buying a home, the last thing you want is a health hazard hiding behind your front door. While most buyers are concerned about big-ticket items like leaky roofs, faulty wiring, and cracks in the foundation, one of the most important things to test for is what you can’t see. It’s radon.
Including radon testing during your home inspection is an easy step and inexpensive addition that can protect your health and give you peace of mind before you sign on the dotted line, whether in Denver, Colorado or Portland, Maine.
What is radon?
Radon is a naturally occurring radioactive gas produced when uranium present in soil, rock, or water decomposes. They can move up through the ground and enter homes through cracks in foundations, gaps around pipes and sump pumps, or crawl spaces.
Although radon cannot be seen, smelled, or tasted, long-term exposure to high levels of radon can be dangerous. According to the U.S. Environmental Protection Agency (EPA), radon is the second leading cause of lung cancer in the United States, killing thousands of people each year.
Radon levels can vary widely from property to property and even between adjacent homes, so each home must be tested individually. Even if there have been no problems in the past, fluctuations in weather, climate, and temperature can also affect radon levels. This makes radon testing an important part of the home inspection process for buyers.
What does a radon test do?
During a standard home inspection, inspectors check areas of the home such as the foundation, plumbing, HVAC, and electrical equipment, but radon testing is not always included automatically. Typically, you will need to request this as an additional service or hire a certified radon specialist separately.
When a home inspection includes a radon test, the inspector installs a testing device in the most habitable area of the home, such as the basement or first floor, and measures gas levels over several days. Accurate results require a “closed environment” (e.g., windows and doors closed for at least 12 hours before and during testing).
If a radon mitigation system is already installed, the inspector can also test whether it is functioning properly.
Different types of radon tests
There are several ways to measure indoor radon levels. DIY radon tests and professional radon tests both track the amount of radon gas that builds up in your home, but the processes and test times are different.
Passive or DIY Radon Test Kit
Passive radon devices are available at most hardware stores. It uses natural air diffusion to collect radon particles over a period of time (usually about a week). Charcoal canisters are most commonly used in DIY radon tests and absorb radon over several days. Once testing is complete, the device is sent to a laboratory for analysis.
Pros: Affordable, easy, and do-it-yourself.
Disadvantages: Readings can be inaccurate if the instructions and conditions are not followed exactly.
Active or continuous radon testing
Active devices are those used by professional radon inspectors. A continuous radon monitor (CRM) records radon levels in real time. It records hourly readings and environmental factors such as humidity and air pressure, providing a detailed understanding of radon fluctuations and helping detect tampering and ventilation changes. Once the test is complete (usually after 48 hours), your report will be ready.
Pros: Fast and accurate, perfect for real estate transactions.
Disadvantages: High cost and must be operated by a certified professional.
For best results, ongoing radon testing by a professional is recommended. In the case of real estate transactions, an inspection by a professional is mandatory.
How much does a radon test cost?
On average, buyers can expect to pay between $100 and $250 when radon testing is added to a home inspection package, and homeowners and sellers can expect to pay between $300 and $600 when ordered as a standalone service.
Although costs vary, radon testing is a small price to pay in the grand scheme of home ownership. If high levels are found, you will know before closing so you can negotiate mitigation and remediation without the risk of discovering problems later and causing long-term health problems.
How long does a radon home inspection take?
Although most homebuyers choose a short-term inspection during the inspection period, a long-term inspection after move-in can be worthwhile, especially if you are planning a basement renovation, finishing a lower floor, or live in an area with a high risk of radon exposure.
Short-term testing: Most professional radon tests are performed in 48 hours or two days. This period is consistent with standard testing periods and provides fast, reliable results to help inform purchasing decisions.
Long-term tests: These tests use alpha particle tracking to monitor radon levels over time and run from 90 days to a year. Because radon levels fluctuate with weather and home ventilation patterns, long-term testing provides the most accurate average values.
Follow-up Testing: If the short-term test results are close to the EPA action level (approximately 4.0 pCi/L), the buyer or homeowner is often recommended to perform another test, either a second short-term test for confirmation or a long-term test for accuracy.
What your home inspection radon test results mean
The EPA measures radon levels in picocuries per liter of air (pCi/L). Above 4.0 pCi/L, the amount of radon detected is considered a concern.
Less than 2.0 pCi/L: Low level. There is no need to act immediately. 2.0 to 3.9 pCi/L: Medium level. Consider retesting to improve accuracy. 4.0 pCi/L or higher: Treatment (e.g., repair) is recommended
If the test result is greater than 4.0 pCi/L, EPA recommends that you take steps to reduce radon levels before or immediately after occupancy. Even if the levels are just below that threshold, many homebuyers choose to proactively install mitigation systems.
What happens if a home inspection finds high levels of radon?
High radon levels don’t mean you should leave your home. In fact, radon problems are very common and generally low cost and very fixable. The solution is usually to install a radon mitigation system that helps vent the gas outdoors safely. Most sellers are willing to work with you because radon problems are fixable and disclosure laws require you to be honest about known problems.
Professional radon mitigation systems, such as pipes and fan systems, typically cost between $800 and $1,500, depending on the size of your home and the type of foundation. Once installed, they can reduce radon levels by up to 99%, and most systems are quiet, energy efficient, and easy to maintain.
After installation, follow-up tests are performed to ensure that the system is working properly. We recommend continuous retesting every two years. If you renovate your basement or change your HVAC system, we recommend retesting sooner.
Steps to reduce radon levels
Seal cracks and gaps in your foundation: Use caulk or polyurethane sealant to close openings around pipes, drains, and floor joints where radon can enter. Improve ventilation: Use existing fans, add an air exchanger, or open windows and doors from time to time to increase airflow and dilute indoor radon levels. Treat the water if necessary: In rare cases, radon can enter your home through well water, so it may be helpful to install a water filtration or aeration system. Use radon-resistant techniques during renovations: When remodeling or refinishing your basement, proactively add vapor barriers, subslab vents, or sealed sump covers to prevent future buildup. Install a radon mitigation system: A licensed contractor can add ventilation pipes and fan systems that suck radon from beneath the foundation and release it safely outside.
Which homes are at highest risk for radon?
Radon is present in every home, but certain factors make some properties more vulnerable than others. Radon enters through cracks in the foundation, sump pumps, crawlspaces, and gaps around pipes, so the way your home is built and maintained has a big impact on how much gas accumulates indoors.
Homes most at risk for high radon concentrations are:
Homes with basements or crawl spaces: Because radon seeps through the soil, homes with earthen foundations, outdoor crawl spaces, or other exposed ground to living spaces can have higher radon levels than homes built on slabs. Older homes with cracks in their foundations: As they settle over time, small gaps open up, allowing more radon to enter. Well-sealed, energy-efficient homes: Ironically, new, well-insulated homes can trap radon indoors because there is less natural air circulation. Homes in high-radon areas: The EPA notes that high-risk areas include the Midwest, Northeast, Appalachian, and Rocky Mountain states, where uranium-rich soils release more radon gas. However, increased radon levels have been observed in every state in the United States. Neighboring homes with known radon problems: Radon can vary widely from property to property, even on the same street. However, if your neighbor has high levels, the soil on your property may as well. Homes that rely on well water: Radon can seep from groundwater, so if your home has a well, it’s important to have it tested and treated if necessary.
No home is completely immune to radon, and even newly built homes can have elevated readings. Although many local builders are now incorporating radon-resistant building techniques such as vent pipes and vapor barriers, testing after occupancy or as part of a new home inspection is still recommended.
Is a radon test really necessary?
The short answer is yes. Radon testing during a home inspection is definitely worth it. Radon is colorless and odorless, so the only way to know if radon is present at dangerous levels is to test. The EPA estimates that approximately 1 in 15 homes in the United States has elevated radon levels, and that any state can experience elevated radon levels, regardless of the age of the home or the type of foundation.
Changes in weather, climate, and temperature can cause changes in the soil that can cause radon to form and enter your home, so testing every two years is recommended even if levels have been OK in the past.
That’s why including radon testing in your home inspection can protect both your health and your home in the long term. If high levels are detected, you can negotiate mitigation with the seller or make a plan for remediation before you move in. Even if the results are low, it is better to know that your health is safe. At a nominal cost, radon testing is one of the smartest and easiest steps you can take when purchasing a home.
