--- title: Do Older Homes Have More Radon? canonical: "https://radonmitigationyorkpa.net/radon-guide/do-older-homes-have-more-radon/" pubDate: "2026-10-01T00:00:00.000Z" updatedDate: "2026-10-03T00:18:00.000Z" author: Radon Mitigation York PA description: "Age doesn't cause radon, but old foundations often let more in. Learn why older homes often test higher and why new homes still need a test." --- # Do Older Homes Have More Radon? Older homes do not have more radon because of their age. Radon levels depend on the soil under the house and how easily soil gas gets through the foundation. Older homes often test higher because they tend to have leaky stone or block walls, cracked slabs, dirt areas and open drains. New homes can test high too. Those leaks are what [older-home radon mitigation](/services/older-home-radon-mitigation/) is built to seal. ## Age is not the cause Radon comes from the ground. It forms as uranium in soil and rock breaks down, then moves up through the soil and into any building sitting on it. The amount that ends up inside depends on three things: 1. **How much radon is in the soil** under and around the house. 2. **How easily soil gas can get in** through the foundation. 3. **How strongly the house pulls air from the soil**, mainly through the stack effect. A house's age does not change the soil. A 1920s rowhome and a 2020s townhouse on the same ground sit on the same source. The EPA's [Citizen's Guide to Radon](https://www.epa.gov/sites/default/files/2016-12/documents/2016_a_citizens_guide_to_radon.pdf) says any home can have a radon problem: new and old homes, well-sealed and drafty homes, and homes with or without basements. ## Why older homes often test higher anyway Older foundations tend to have more and bigger openings. Common features include: - **Fieldstone and rubble walls.** Every mortar joint is a possible gas path, and old lime mortar wears away. - **Hollow block walls.** The open cores carry gas up the wall. - **Thin, cracked or patched slabs**, often poured right on soil with no gravel or plastic under them. - **Dirt floors and dirt areas**, like old coal bins or space under additions. - **Open floor drains and sump pits** that connect straight to the soil. - **A gap where the floor meets the wall.** Older homes were also built before radon was widely understood. Newer homes are more likely to have a plastic sheet under the slab, sealed joints, or a passive radon pipe built in. Those features do not guarantee a low result, but they help. ## Why "drafty" does not mean "safe" Many people assume an old, drafty house lets radon escape. In practice, air leaks can make things worse. Warm air leaking out the top of the house in winter pulls replacement air in at the bottom, including soil gas through the foundation. That is the stack effect. A leaky attic and a leaky basement together can draw more radon in, not less. ## Moisture and old basements Older basements are also more likely to be damp, which matters for radon in two ways. Water problems usually mean cracks, drains and sumps, all of which are gas paths. And wet soil under a slab can make a radon system harder to design, since water blocks airflow. Our guide on [radon mitigation in a wet or damp basement](/radon-guide/wet-basement-radon-mitigation/) covers how systems handle it. ## What about new homes? New homes are not off the hook. Even with better slabs, new concrete cracks as it cures, and plumbing and utility holes still pass through the floor. New homes are also built tighter, and tighter houses can hold radon in once it enters. The only way to know any home's level is to test it. ## Older homes in York York has a large stock of older housing. The city has many older brick rowhomes and twins, and older neighborhoods often sit on fieldstone foundations. Mid-century suburbs around the city tend to have hollow block basements. York County is also in EPA Radon Zone 1, the highest potential category. Put those together and older York homes are a group where testing really matters. ## Key takeaways - Radon comes from the soil, not the age of the house. - Older homes often test higher because of leakier foundations. - Drafty houses can pull more radon in, not less. - New homes can test high too. Every home should be tested. - Older homes can be fixed, but they may need extra suction points or sealing. ## Frequently Asked Questions ### Should I test an older home before I buy it? Yes. A radon test during the inspection period is common in Pennsylvania home sales. It gives you time to plan a fix. ### Can an old house be mitigated as well as a new one? Yes. It may take more design work, but older homes can reach the same clearance levels as newer ones. ### Does renovating an old house change its radon level? It can. New windows, insulation and air sealing change how air moves, so retest after major work. ## Talk to us about your older home If your older home tested high, the fix depends on what the foundation looks like. See how we handle older-home radon mitigation in York, or call [(717) 356-3035](tel:+17173563035) any time for a same-day callback.