Gasketed sump lids, sealed floor-wall joints, and closed slab penetrations. Rarely enough alone — but it makes the system that follows work properly.
This comes up often enough here that most certified crews in the county have a settled way of handling it.
How this normally comes up
- Utility penetrations and floor drains with nothing around them
- A crawl-space hatch that soil gas moves straight through
- An open sump pit sitting in a finished basement
- A visible gap where the slab meets the foundation wall
What the work involves
Sealing on its own rarely brings a house below the action level and should not be sold as though it will. What it does is make an active system work harder for its money by cutting the leakage paths that otherwise short-circuit the suction — so it is nearly always done as part of an install rather than instead of one.
Typical cost in Hunterdon County, NJ
$400 – $1,300 — typical range, not a quote. What your building needs can only be settled by a certified business that measures it on site.
Certification, checked before referral
Installing radon mitigation for a fee in New Jersey requires NJDEP certification as a radon mitigation business, affiliated with a certified radon mitigation specialist (N.J.A.C. 7:28-27). We confirm that on the NJDEP register and record the date we checked. That is a check, not an endorsement — satisfy yourself before you hire.
System running and the reading hasn't moved?
One description is enough. We'll send it to certified local crews and leave the decision entirely with you.
Tell us what you've got →Coverage
Towns where this is the right question
These are the towns whose geology and housing stock actually put this on the table.
Highlands ridge and limestone valley
Precambrian gneiss and granite of the Reading Prong, cut by carbonate valleys. The highest-potential ground in the county, and almost all of it on private wells.
Newark Basin shale country
Red shale and mudstone of the Passaic Formation under Flemington and the centre of the county. Fractured rock, plenty of basements, and a mix of public water and wells.
Diabase uplands and the Delaware corridor
Sourland-type diabase and the dark argillite of the Lockatong Formation. Stone farmhouses, open crawl spaces, and river-town cellars cut into rock.