When people think about radon, they usually picture a basement. So, if your home sits on a slab or has a crawl space, it's easy to assume radon isn't something you need to worry about. Unfortunately, that's a common myth. Homes without basements can still have elevated radon levels, and the only way to know is with professional radon testing.
Here's what New Jersey homeowners should know about radon in slab-on-grade and crawl space homes, and how to keep your indoor air healthier.
What Is Radon and How Does It Enter a Home?
Radon is a naturally occurring radioactive gas that forms when uranium in soil and rock breaks down. It has no color, smell, or taste. As it moves up through the ground, radon can enter a home through any opening where the house meets the soil, including cracks in concrete, construction joints, gaps around pipes and utility lines, sump pits, and exposed soil in crawl spaces.
The U.S. Environmental Protection Agency (EPA) identifies radon as the leading cause of lung cancer among nonsmokers. For a helpful primer, this overview of what radon is from a Tennessee radon company covers the basics.
Do Homes Without Basements Need Radon Testing?
Yes. The EPA recommends testing all homes below the third floor for radon, regardless of foundation type. Radon comes from the ground beneath your home, so any house in contact with soil can be affected. That includes:
- Slab-on-grade homes
- Homes with crawl spaces
- Homes with a mix of basement, slab, and crawl space foundations
- New construction and older homes alike
Two neighboring homes built the same way can have very different radon levels, so a test is the only way to know what's happening in your house. Learn more about why some homes have high radon concentrations.
Can a Slab-on-Grade Home Have High Radon?
It can. A concrete slab may look solid, but over time it can develop cracks, and there are often openings around plumbing penetrations, expansion joints, and the edges where the slab meets the foundation walls. Since living spaces in slab homes sit right on top of the concrete, any radon that enters goes directly into the rooms where your family spends time.
What About Homes With Crawl Spaces?
Crawl spaces, especially those with exposed dirt floors, can allow radon to collect and move up into the home. Air naturally flows from lower areas into the living space above, carrying radon with it. Vented crawl spaces may dilute some radon, but they don't eliminate the risk. Testing is still the only way to know your levels.
Why Can Air Pressure Pull Radon Into Homes Without Basements?
Homes often have slightly lower air pressure indoors than in the soil beneath them, especially when the heat is running in winter. Warm air rises and escapes through the upper parts of the house, which pulls replacement air, and soil gas, in from below. Exhaust fans, dryers, and fireplaces can add to this effect. Radon specialists in North Carolina explain this well in their resource on why air pressure pulls radon into your home.
Where Should a Radon Test Be Placed in a Home Without a Basement?
Radon tests should be placed in the lowest level of the home that is used or could be used as living space. In a slab or crawl space home, that's usually the main floor. A good test location is:
- In a frequently used room, such as a living room or bedroom
- Away from exterior doors, windows, and vents
- Away from kitchens, bathrooms, and laundry rooms where humidity is higher
- About 20 inches or more above the floor
Professional testing with a Continuous Radon Monitor (CRM) records levels hour by hour, giving you a clear picture of how radon behaves in your home.
What Radon Level Means You Should Take Action?
The EPA recommends mitigation if your home tests at 4.0 picocuries per liter (pCi/L) or higher and suggests considering it for levels between 2.0 and 4.0 pCi/L. The World Health Organization (WHO) recommends a lower reference level of 2.7 pCi/L. Since no level of radon is considered completely safe, reducing it as much as practical is a smart goal.
How Is Radon Mitigation Done in a Home Without a Basement?
Mitigation methods are tailored to your home's foundation:
Slab-on-Grade Homes
Most slab homes use sub-slab depressurization. A technician creates a suction point through the slab, then installs a vent pipe and fan that draw radon from beneath the concrete and release it safely above the roofline.
Crawl Space Homes
Crawl spaces are often treated with sub-membrane depressurization. A durable plastic barrier is sealed over the crawl space floor, and a fan system draws radon from beneath the membrane and vents it outside.
In both cases, sealing major cracks and openings helps the system work more effectively. After installation, a follow-up test confirms your levels have dropped. Learn more about our radon mitigation services.
Should You Test for Radon When Buying or Selling a Home Without a Basement?
Yes. Foundation type doesn't change the need for testing during a real estate transaction. Testing early in the process gives buyers and sellers clear information and time to plan if mitigation is needed. We work with home buyers and sellers throughout Northern and Central New Jersey to keep the process smooth.
Whether your home has a basement, a slab, or a crawl space, testing is the only way to know your radon levels. Advanced Radon Services provides professional radon testing and mitigation for homeowners in Newark and throughout Northern and Central New Jersey. Contact us today to schedule your radon test.
