Barndominiums—barn-style homes known for their open spaces, affordability, and customizability—have surged in popularity across the U.S. But like any residential structure, they come with their own set of health and safety concerns. One issue that often gets overlooked during construction or remodeling is radon gas. Radon is an invisible, odorless, radioactive gas that can accumulate in homes and lead to serious health consequences. Whether you’re building a barndominium from the ground up or living in one already, understanding radon and how to mitigate it is essential for long-term health and safety. In this guide, we’ll walk you through everything you need to know about radon in barndominiums, including how it forms, why it’s dangerous, how to test for it, and how to implement effective mitigation strategies.
What Is Radon?
Radon is a naturally occurring radioactive gas that results from the decay of uranium in soil, rock, and water. It’s present in almost every part of the U.S. in varying levels. While the gas itself is harmless in trace amounts outdoors, it becomes a health risk when it accumulates indoors—particularly in enclosed spaces with poor ventilation. The Environmental Protection Agency (EPA) estimates that radon exposure is the second leading cause of lung cancer in the U.S., responsible for around 21,000 deaths per year. Long-term exposure to high radon levels can significantly increase your risk, even if you’ve never smoked.
Why Are Barndominiums at Risk?
Barndominiums, especially those built on concrete slab foundations, are just as susceptible to radon as traditional homes. In fact, depending on the construction style and site location, they may even be more vulnerable due to certain common design choices:
- Concrete Slab Foundations: Many barndos are built on slab-on-grade foundations, which can allow radon to seep in through cracks, seams, or plumbing penetrations.
- Metal Construction: Metal buildings are often tightly sealed, reducing airflow and ventilation. While energy-efficient, this can trap radon indoors.
- Rural Settings: Barndominiums are typically built in rural areas where radon levels in soil may be higher, and where fewer homes have previously been tested for radon.
How Does Radon Enter a Barndominium?
Radon enters buildings through the following pathways:
- Cracks in concrete slabs or foundation walls
- Gaps around pipes, drains, or wiring
- Construction joints between walls and floors
- Sump pumps or crawl spaces
- Poorly sealed doors and windows in basements
Once inside, radon becomes concentrated if not properly vented out. Because barndominiums often have large, open floor plans and expansive ground contact surfaces, they provide radon with plenty of entry points—and ample space to accumulate.
How to Test for Radon in Your Barndominium
Before you can mitigate radon, you need to measure current levels. Radon testing is relatively inexpensive and easy to perform. Here are your options:
- Short-Term Test Kits
These kits are available at hardware stores or online and typically take 2–7 days to complete. They are a good starting point for an initial screening. Once the test period ends, the sample is mailed to a lab for analysis.
- Long-Term Test Kits
These monitor radon levels for 90 days or longer, giving a more accurate picture of year-round exposure. Ideal if you’re trying to determine whether mitigation is necessary.
- Professional Testing
Hiring a certified radon mitigation professional is often the most reliable way to get precise results. They use continuous radon monitors and can assess different parts of the home. The EPA recommends taking action if radon levels are 4.0 picocuries per liter (pCi/L) or higher.
Barndominium Radon Mitigation Strategies
If your barndominium tests high for radon, don’t panic. Radon mitigation systems are highly effective and can often reduce levels by 99% or more. Here are the most common and effective mitigation methods:
- Sub-Slab Depressurization System (SSD)
This is the gold standard for homes with slab foundations—typical in barndominiums.
- A PVC pipe is inserted through the slab into the gravel layer beneath.
- A fan attached to the pipe draws radon from under the slab and vents it above the roof.
- This creates a vacuum under the foundation, preventing radon from entering the home.
Cost: $800 to $2,500 depending on complexity.
- Sealing Cracks and Gaps
While sealing alone is not a full mitigation method, it supports other systems by minimizing radon entry points. Key areas to seal include:
- Foundation cracks
- Joints around floor-to-wall seams
- Plumbing and electrical penetrations
Use polyurethane caulk or specialized radon-resistant sealants.
- Crawl Space Ventilation
If your barndominium has a crawl space, it can act as a major radon entryway. There are two options:
- Passive Ventilation: Installing vents to promote natural air circulation.
- Active Ventilation: Using fans to mechanically exhaust radon-laden air.
Alternatively, you can install a sub-membrane depressurization system—a plastic sheet placed over the crawlspace floor connected to a suction fan.
- Heat Recovery Ventilators (HRVs)
HRVs help by increasing air exchange rates in the home. These systems are especially useful in tightly sealed metal buildings and can work alongside other mitigation strategies to dilute radon concentration. Bonus: They also improve indoor air quality.
Building a New Barndominium? Plan for Radon Mitigation from Day One
The best time to address radon is during the construction phase. Including radon-resistant features in your barndominium design costs less upfront than retrofitting a system later. Here’s what to consider:
- Install a passive radon venting system beneath the foundation.
- Use a radon barrier membrane over the soil or gravel layer.
- Design with good natural ventilation in mind.
- Seal all foundation and slab penetrations during the build.
Radon-resistant construction features may cost an additional $300–$800, but they offer long-term peace of mind and can be a major selling point if you ever decide to list your barndominium.
Choosing a Radon Mitigation Professional
If you decide to hire a pro, make sure they are certified by:
- National Radon Proficiency Program (NRPP)
- National Radon Safety Board (NRSB)
Ask about their experience with barndominiums or similar metal and slab-on-grade structures. Get multiple quotes and make sure the system includes post-installation testing to verify its effectiveness.
Final Thoughts
Radon is a serious but manageable issue for barndominium owners. With the right testing and mitigation strategies, you can ensure your home remains a safe and healthy environment for years to come. Whether you’re planning your dream barndominium or already living in one, don’t overlook radon protection. It’s a small investment that could have a lifesaving impact.
FAQs About Radon in Barndominiums
Q: How often should I test my barndominium for radon? A: Test every 2–5 years, or after major renovations or changes to your HVAC system.
Q: Are radon levels higher in certain states? A: Yes. States like Colorado, Iowa, Pennsylvania, and parts of the Midwest often have higher radon levels. Check your area’s radon map on the EPA’s website.
Q: Can I install a mitigation system myself? A: DIY kits exist, but improper installation can reduce effectiveness. Professional installation is strongly recommended. If you’re designing or updating a barndominium and need advice on safe building practices—including radon mitigation—don’t hesitate to consult with professionals who specialize in barndo construction and indoor air quality.