Your radon test came back at 6.2 pCi/L. The EPA’s action level is 4.0 pCi/L (picocuries per liter, the standard unit for measuring radon concentration in air). So now what? The good news is that radon mitigation is one of the most effective and well-understood fixes in residential environmental safety. A properly installed system can reduce radon levels by 80% to 99%, and most installations take less than a day.
Here’s what you need to know about how these systems work, what they cost, and what to look for when hiring a contractor.
How Radon Gets In
Radon is a naturally occurring radioactive gas produced by the decay of uranium in soil and rock. It seeps into your home through any point where the building contacts the ground: cracks in the foundation slab, gaps around plumbing penetrations, sump pits, and even through porous concrete itself. Because the air pressure inside your home is typically lower than the pressure in the soil beneath it, your house acts like a gentle vacuum, pulling soil gases upward through any available pathway.
The EPA estimates that radon causes approximately 21,000 lung cancer deaths per year in the United States. It is the leading cause of lung cancer among non-smokers.
Sub-Slab Depressurization: The Standard Fix
The most common and effective radon mitigation method is called sub-slab depressurization (SSD), sometimes referred to as active soil depressurization (ASD). The concept is straightforward: instead of letting your home pull radon-laden air up from the soil, you install a system that pulls that air out before it enters your living space and vents it safely above the roofline.
How It Works
A mitigation contractor cores a small hole (typically 4 to 5 inches in diameter) through your foundation slab. Beneath the slab, they create a small suction pit in the aggregate or soil. A PVC pipe is inserted into this hole and routed up through the building, either inside through a closet or utility space, or along the exterior wall. At some point along the pipe, a specialized inline fan creates continuous negative pressure beneath the slab.
The fan runs 24 hours a day, drawing air from beneath your foundation and exhausting it above the roofline where it disperses harmlessly into the outdoor atmosphere. Radon concentrations outdoors are negligible because the gas dilutes rapidly in open air.
A small U-tube manometer (a simple liquid-filled pressure gauge) is typically installed on the pipe so you can visually confirm the system is operating. If the liquid levels are uneven, the fan is creating suction. If they’re level, something needs attention.
Why It Works So Well
SSD systems are effective because they address the fundamental physics of the problem. Instead of trying to seal every crack and gap in a foundation, which is nearly impossible, the system reverses the pressure differential. The soil beneath your slab now has lower pressure than the surrounding soil, so radon-laden air gets pulled toward the suction point and up the pipe rather than into your home.
The EPA’s Consumer’s Guide to Radon Reduction reports that SSD systems typically reduce indoor radon levels to below 2.0 pCi/L, even in homes that initially tested well above the action level.
Other Mitigation Approaches
Crawl Space Systems
Homes built over crawl spaces require a different approach. If the crawl space has exposed soil, the standard method involves laying a heavy-duty polyethylene vapor barrier over the entire soil surface, sealing it at the edges and around any piers or penetrations, and then installing a suction pipe and fan beneath the barrier. This is sometimes called sub-membrane depressurization (SMD).
In the Augusta area and throughout the CSRA, crawl space homes are common, and Georgia’s humid climate makes vapor barriers beneficial for moisture control as well. A properly installed SMD system addresses both radon and moisture issues simultaneously.
Sump Pit Suction
If your home has a sump pit, it can sometimes serve as the suction point for a radon system, eliminating the need to core through the slab. The sump cover is sealed with a gasketed lid, and the suction pipe connects to the sealed pit. This approach works well when the sump pit is centrally located and the sub-slab aggregate allows good air flow.
Passive vs. Active Systems
Some newer homes are built with passive radon reduction features: a gas-permeable layer beneath the slab, sealed penetrations, and a PVC pipe running from below the slab to above the roof. These passive systems rely on natural air convection rather than a fan. They can reduce radon levels modestly, but if your home tests above 4.0 pCi/L with a passive system in place, adding a fan to convert it to an active system is a straightforward upgrade.
What It Costs
Radon mitigation costs vary based on your home’s foundation type, size, and complexity, but here are realistic ranges for the Augusta and CSRA market:
Standard slab-on-grade home: $800 to $1,500 for a single suction point system. Most homes in this category fall in the $1,000 to $1,200 range.
Crawl space home with SMD: $1,200 to $2,000, reflecting the additional labor for vapor barrier installation and sealing.
Complex foundations (multiple slabs, additions, split levels): $1,500 to $2,500 or more. Homes with multiple foundation types or large footprints may need additional suction points, each adding to the cost.
Fan replacement: Mitigation fans have a lifespan of roughly 5 to 10 years. Replacement fans cost $150 to $300, and installation is straightforward.
Operating cost: A mitigation fan uses about as much electricity as a 75-watt light bulb running continuously, roughly $50 to $80 per year.
These costs are modest compared to the health risk of long-term radon exposure. The CDC notes that radon is the second leading cause of lung cancer in the United States, and the risk increases with both concentration and duration of exposure.
What to Look for in a Contractor
Radon mitigation is a specialized field. Not every general contractor or home inspector is qualified to install a system correctly. Here’s what to look for:
Certification. Look for contractors certified by the National Radon Proficiency Program (NRPP) or the National Radon Safety Board (NRSB). Certification means the contractor has completed training, passed exams, and follows established installation standards.
Post-mitigation testing. A reputable contractor will either provide a post-installation radon test or strongly recommend you conduct one. The system should be tested 24 to 48 hours after installation to confirm it’s achieving the target reduction.
Written guarantee. Many mitigation contractors guarantee their system will reduce radon levels below 4.0 pCi/L, with a commitment to make adjustments at no additional cost if the initial installation doesn’t achieve that target.
System labeling. A properly installed system will include labels identifying it as a radon mitigation system, the installer’s contact information, and a visible manometer for ongoing monitoring.
After Installation
Once your system is running, maintenance is minimal. Check the manometer periodically to confirm the fan is operating. Listen for the fan when you walk past the pipe, as it produces a low, steady hum. If it goes silent, the fan may need replacement.
The EPA recommends retesting your home every two years after mitigation to confirm the system continues to perform. Conditions beneath your foundation can change over time as soil settles and new cracks develop.
- If you’ve tested above 4.0 pCi/L, get quotes from two or three certified mitigation contractors. Ask about their approach for your specific foundation type.
- If you have a passive system that isn’t achieving safe levels, adding a fan is typically a quick, inexpensive upgrade.
- If your system has been running for more than two years without retesting, schedule a test to verify it’s still performing.
If you want help understanding your radon test results or need guidance on next steps, the EnviroPro 360 team can walk you through your options. Reach out any time and we’ll point you in the right direction.
