Guide
How does radon mitigation actually work?
Most systems are one idea executed carefully: keep the soil under the house at lower pressure than the rooms above it, so radon vents outdoors instead of seeping in. Here is what that means in practice.
Guidance reviewed against EPA and PA DEP source material: July 22, 2026
The core design
What is active soil depressurization?
The installer drills a suction point through the basement slab (or sets one under a sealed membrane in a crawlspace), connects it to a vent pipe routed above the roofline, and puts an inline fan in the run. The fan holds the soil gas under the foundation at lower pressure than the house, reversing the flow that pulled radon inside. Cracks and joints get sealed so the fan's suction works on the soil instead of leaking room air. The visible parts — a pipe and a quiet fan — undersell the part that matters, which is whether the suction field actually reaches every section of soil the house sits on.
Foundation drives design
Why do quotes differ so much between homes?
Because foundations differ. A single-pour basement is the easy case. A home with a basement plus a slab-on-grade addition plus a crawlspace has three separate soil-contact zones, and a suction point in one does not automatically treat the others: additions may need their own point, crawlspaces typically get a sealed membrane with its own suction, and sump pits often become the suction location with a sealed lid. This is why a useful quote itemizes each foundation area by name — and why the cheapest one-pipe bid on a three-zone house deserves skepticism.
Cost
What does mitigation cost?
Honest answer: EPA deliberately publishes no dollar figure. Its guidance says most homes can be fixed for about the same cost as other common home repairs and tells homeowners to get estimates from qualified mitigators. Industry marketing sites commonly report ranges around $800–$2,500 for a standard system — treat those as contractor-reported, not government-verified. What actually protects your wallet: multiple quotes from PA DEP-certified mitigators, each itemizing every foundation area, fan and pipe placement, electrical work, and a post-mitigation test.
Proof
How do you know it worked?
A post-mitigation test under the standard rules — minimum 48 hours, closed-house conditions held 12 hours before and throughout, system running normally — with an average below 4.0 pCi/L. The system is not "done" at installation; it is done when the number says so, and periodic retesting keeps that true as fans age and homes change. Details on the post-mitigation retesting page.
Clear next step
Request Chester County radon testing or mitigation routing.
Use this for first tests, real-estate deadlines, 4.0+ pCi/L results, mitigation planning, and post-mitigation retests.
Requests are routed only where an appropriate PA DEP-certified provider is available.
FAQ
Common homeowner questions
What is active soil depressurization?
The standard radon fix: a suction point through the slab connected to a vent pipe and inline fan that keeps the soil under the home at lower pressure than the living space, so radon vents above the roof instead of entering the house.
Does every home get the same system?
No. Suction-point count and placement depend on the foundation: basements, slabs, crawlspaces, and additions each need their own handling, and a home with several soil-contact sections may need more than one point.
How much does radon mitigation cost?
EPA does not publish a dollar figure; it says most homes can be fixed for about the cost of other common home repairs and recommends getting estimates from qualified mitigators. Industry sites commonly report roughly $800–$2,500 for standard systems, but those figures are contractor-reported, not government-verified. Get multiple quotes from PA DEP-certified mitigators.
How do I know the system worked?
A post-mitigation test: minimum 48 hours under closed-house conditions with the system running. The average should be below 4.0 pCi/L — and lower is better.
Who is allowed to install mitigation in Pennsylvania?
Hired radon mitigation work in Pennsylvania requires PA DEP certification. Verify any provider in the PA DEP Radon Services Directory before hiring.