While radon is found in outdoor air in trace amounts, it becomes dangerous when it gets trapped and concentrated inside a residence. But how does radon enter a home in the first place? Many homeowners believe that if their foundation is “solid,” they are safe. In reality, radon is a persistent traveler, sneaking in ways you may not expect. And, oftentimes, the tighter homes are the ones most at risk.
The Most Common Ways Radon Enters Your Home
1. Foundation Cracks
Even the most well-built homes eventually settle, and settling leads to cracks. While a hairline crack in your concrete slab or basement wall might seem structurally insignificant, to a gas molecule like radon, it’s a wide-open door.
Radon is under pressure in the soil. When it encounters a fracture in the concrete (a vertical crack in a foundation wall, a horizontal spiderweb crack in the floor, etc.) the pressure differential pulls the gas inside. Because concrete is porous, even seemingly “solid” slabs can allow some gas to permeate…but distinct cracks are the most efficient expressways for radon.
2. Sump Pump Pits
Sump pumps are essential for avoid floods in your home’s lower levels, but if they are not properly outfitted, they are one of the most notorious contributors to high radon levels. A sump pit is essentially a large hole dug directly into the earth under your home – a perfect spot for radon to sneak in.
If the pit is left open or has a loose-fitting lid, there is zero physical barrier between the soil gases and your basement air. Radon collects in the drain tiles around your house and is channeled directly into the sump basin. Without a radon-sealed lid (which includes airtight gaskets and sealed portals for the discharge pipes), the sump pit acts like a chimney, venting soil gas directly into your home.
3. Construction Joints
Houses are not poured as a single, seamless cube of concrete. They are built in stages. One of the most common radon entry points is the “floating slab” joint, or the perimeter gap where the basement floor meets the foundation wall.
During construction, these joints are necessary to allow for the expansion and contraction of materials. However, if they aren’t sealed with a specialized polyurethane caulk, they remain permanent air gaps. Because these joints run the entire perimeter of the basement, they represent a massive surface area for radon to seep through.
4. Service Pipe Gaps
Your home is connected to the outside world through a network of utilities. Plumbing stacks, electrical conduits, and gas lines all must penetrate the foundation to reach the interior.
Often, the holes drilled for these pipes are slightly larger than the pipes themselves. If the annular space around these penetrations isn’t hermetically sealed, it creates a straw effect. Radon gas follows the disturbed soil around the utility lines and is pulled through the gaps around the pipes. This is especially common under kitchen sinks or behind water heaters where pipes disappear into the floor.
5. Floor Drains and Dry P-Traps
Basement floor drains are designed to whisk away water from water heater leaks or floor cleaning. These drains connect to a series of pipes that often sit directly in the soil or connect to a dry well.
Most drains have a “P-trap” – a U-shaped pipe that holds water to block sewer gases. However, if a basement drain is rarely used, the water in that trap can evaporate. Once the trap is dry, it no longer provides a seal, allowing radon from the underlying soil or the drainage system to rise freely into the room. Simply pouring a cup of water down your floor drains every few months is a simple but vital maintenance step.
6. Crawlspaces
Perhaps the most significant risk factor for high radon levels is a dirt-floor crawlspace. In these homes, there is no physical barrier whatsoever between the earth and the wood-framed floor joists.
The soil “breathes” radon directly into the crawlspace air. Because the floor above is rarely airtight, the vacuum effect of the house pulls that contaminated air up through floorboards, HVAC ductwork, and wiring holes into the main living areas. In these cases, crawl space encapsulation is the gold standard for radon protection
How Can I Protect My Home From Radon?
Understanding how radon enters is the first step toward mitigation. Because you cannot see or smell the gas, the best way to know if these pathways are compromising your air quality is to invest in professional radon testing services with our experts.
From there, if your levels are above the EPA’s action level (4.0 pCi/L), we can discuss the next steps of radon mitigation. Reach out to Dakota Radon Pros today.