Radon Mitigation Cost Calculator

How much does radon mitigation cost in 2026?

Radon mitigation costs $800 to $2,500 for a standard sub-slab depressurization system — the most common method, used in roughly 80-90% of residential installations. The national average lands around $1,100 to $1,600, with a reported median near $1,111 across thousands of residential jobs. Crawl space and block wall systems typically cost more, since they require additional preparation or a fundamentally different approach. Use our calculator above for an instant estimate based on your specific home.

Radon mitigation cost by system type

Passive sealing — caulk, polyurethane sealant, and a sealed sump lid, with no fan or electricity — is worth understanding clearly: it's rarely a complete fix for a home already testing above the EPA action level. It's more useful as a pre-mitigation cost-reducer that a following active system builds on, or as a preventive measure during new construction, not a standalone solution for an existing high reading.

The EPA action level — and why "below 4" still deserves a second look

The EPA sets 4 picocuries per liter (pCi/L) as its action level — the point at which mitigation is officially recommended. Worth knowing: there is no established "safe" level of radon exposure, and the World Health Organization's recommended action threshold is actually more conservative, at 2.7 pCi/L. The EPA itself recommends considering mitigation for readings between 2 and 4 pCi/L, even though that's technically below its own action threshold, precisely because risk doesn't have a clean floor. Radon is estimated by the EPA to be the second leading cause of lung cancer in the US after smoking, linked to roughly 21,000 deaths annually — context worth keeping in mind if your test result sits in that "technically below 4, but not really zero" range.

How sub-slab depressurization actually works

The process is more straightforward than it sounds. A technician drills a 4 to 6 inch hole through the foundation slab into the soil beneath it — this becomes the suction point. A 3 to 4 inch PVC pipe runs from that point up through the home (commonly routed through a garage or utility space) and vents above the roofline, typically at least 12 inches above the roof edge. A continuously running fan, using about 30 to 50 watts of electricity — roughly $30 to $50 a year to operate — pulls radon-laden air from beneath the foundation and exhausts it safely outside before it can enter the living space. Most properly installed systems reduce radon levels by 80% to 99%.

Why block-wall homes often need two systems, not one

This is a detail worth knowing if your home has a hollow concrete block foundation. Radon can enter through the soil beneath the slab and separately through the hollow cavities inside the block walls themselves — two different entry pathways. Using only sub-slab depressurization on a block-wall home can leave 30% to 40% of radon sources unaddressed, since it doesn't reach the gas moving through the block cavities. That's why block-wall foundations are often paired with a dedicated block wall depressurization system alongside standard sub-slab suction, rather than relying on one method alone.

Is DIY radon mitigation a good idea?

This deserves more caution than most DIY home projects, for a specific reason: a radon system that isn't working correctly is invisible. Unlike a deck that visibly sags or a leak you can see, a radon system with an undersized fan or a poorly sealed pipe gives no obvious sign of failure — the only way to know is testing, and by then you may have been living with elevated radon for months. DIY materials run roughly $350 to $900 (fan, PVC piping, core bit rental, test kits), but the process genuinely requires expertise in slab drilling, pipe routing, roof penetration, and electrical safety, and many DIY systems fail post-installation testing due to improper fan sizing or pipe sealing issues. Given that the entire point of the system is verified performance, not appearance, this is a project where professional installation with mandatory post-testing is worth the difference in cost.

What to look for in a mitigation contractor

Look specifically for contractors certified through NRPP (National Radon Proficiency Program) or NRSB (National Radon Safety Board) — these are the standard credentialing bodies for radon mitigation work in the US. Whoever you hire, request post-mitigation retesting ($40 to $150) before making final payment. A reputable contractor should welcome this, since it's the only real proof the system is doing its job. If your radon issue is tied to a crawl space with broader moisture problems, our crawl space encapsulation cost calculator covers the vapor barrier and sealing work that often overlaps with radon mitigation prep.

Frequently asked questions