PA DEP certificationMitigation #1725 · Testing #1725
Also offers: crawlspace sub-membrane depressurization, radon-resistant new construction and 2 moreSub-slab depressurization in York County
Sub-slab depressurization is a radon system that pulls radon from under your floor slab before it gets into the house. A fan on a pipe through the slab draws soil gas from underneath and vents it above the roof. 2 PA DEP-certified mitigation companies listed here describe it as a service on their websites.
Which Radon Companies Install Sub-Slab Systems in York County?
These PA DEP-certified companies describe sub-slab depressurization as a service. Check where each is based and ask whether it serves your town.
Filtered by
Sorted by number of Google reviews.
PA DEP certificationMitigation #3355 · Testing #3105
What Is Sub-Slab Depressurization?
The most common radon system. DEP's 2014 fact sheet says over 99 percent of radon systems are this type.
One or more suction pipes go through the slab into the crushed rock or soil below, or in under the slab from outside. DEP's consumer guide says one suction point is often enough. To compare it with drain tile, sump, block wall and crawlspace methods, see how radon mitigation works.
When Do You Need a Sub-Slab Radon System?
When a confirmed test shows 4 pCi/L or more and your house has a basement or a slab-on-grade floor.
Your radon level
DEP's consumer guide says to fix your home if one long-term test or the average of two short-term tests is 4 pCi/L or higher. You may also want to consider it between 2 and 4. See what your radon number means.
Your foundation
It suits a basement or a slab-on-grade floor (concrete poured at ground level). DEP calls it the most common and usually the most reliable method for those houses. A crawlspace under part of the house may need a mix of methods. See crawlspace radon mitigation.
What Happens When a Sub-Slab System Is Installed?
It usually takes less than a day, DEP says. Pennsylvania's rules (25 Pa. Code §§ 240.303, 240.308 and 240.310) set what the certified installer must do:
Inspect first
A thorough visual inspection of the building before any work starts.
Pipe outlet
Pointing up (a 45-degree elbow is allowed), outside, no rain cap. At least 10 feet above the ground, and 10 feet from windows, doors and openings unless 2 feet above them. A pipe on the side of the house must end above the roof edge.
Fan
Not below ground, in a window well, or in heated or cooled space. Not in a basement, crawlspace or other indoor spot under living space.
Sealing
Reachable floor-to-wall cracks, channel drains, expansion and control joints, gaps around pipes through the foundation, and sump pits that let soil gas in, with urethane caulk or equivalent. If you and the installer agree a channel drain must stay open for water, the installer must warn you in writing that it may raise heating and cooling costs, make the system less effective and raise the risk of backdrafting from natural-draft fuel-burning appliances.
Label
On the pipe, readable from 3 feet: "Radon Reduction System", the installer's name, certification number and phone, the install date, and a note to test at least every two years.
Information packet
Fixed to the system: your contracts and warranties, how it works, operating instructions, what the warning device readings mean, and advice to retest at least every 2 years.
Test after
At least 48 hours, starting 24 hours to 30 days after the system is switched on, with the system running the whole time.
Report to DEP
Within 45 days of the fan starting, including your cost and the test result. If someone else does that test and you don't pass the result on, the installer doesn't have to report it.
Once it's running: is my radon system working?
What Should You Ask a Sub-Slab Radon Company?
Their certification number, where the pipe and fan will go, and what level they guarantee.
What's your PA DEP certification number?
Check it on PA DEP's Radon Services Directory, on the mitigation list.
Do you charge for diagnostic tests?
DEP's consumer guide says many companies give free estimates but may charge for these.
Where will the pipe and fan go?
The rules above limit both.
Who does the test after, and when?
The rules say 24 hours to 30 days after the work. DEP also recommends an independent test. See post-mitigation radon testing.
What level do you guarantee, and for how long?
DEP's 2014 fact sheet says to check the written guarantee is to get the home below 4 pCi/L for the quoted price.
Comparing quotes: how to choose a mitigation company and what radon mitigation costs.
Common Questions About Sub-Slab Depressurization
How long does it take to install a radon system?
Less than a day, PA DEP says. After the system has run for at least 24 hours, a follow-up test checks that radon came down.
How much does sub-slab depressurization cost?
PA DEP's 2014 fact sheet says most radon systems cost $800 to $1,200. Cost factors may include local prices, what's under the slab, the size of the home's footprint and how it was built. Those are 2014 figures, so get a current quote.
Can a radon pipe have a rain cap?
No. Pennsylvania's mitigation standards say the outlet must point upward and discharge to the open air. Rain caps aren't allowed; a 45-degree elbow is.
Will the installer seal my basement cracks?
Some of them. The rules list what must be sealed where it can be reached (see Sealing above). Other cracks aren't on the list, so ask.
Keep Reading About Radon Systems
Sources
- 25 Pa. Code § 240.308, Radon mitigation standards for residential buildings
- 25 Pa. Code § 240.310, Testing protocols
- 25 Pa. Code § 240.303, Reporting of information
- PA DEP: Pennsylvania Consumer's Guide to Radon Reduction
- PA DEP fact sheet: Radon Mitigation Systems (2940-FS-DEP4430)
- PA DEP: Radon in the Home
- PA DEP Radon Services Directory
Page last updated Oct 2026.