Sub-slab depressurization is the most common way to lower radon in a home with a basement or slab on grade. It pulls soil gas from under the concrete before it can seep inside. We connect York homeowners with a local contractor who plans the suction point, pipe route, and fan location around how you use your basement.
How Sub-Slab Depressurization Works
Under most basement floors is a layer of gravel or soil. Radon collects there and moves into the house through cracks, joints, drains, and other openings. A sub-slab system creates a small area of lower pressure under the slab so that gas flows into the pipe instead of into the house.
To do that, the contractor drills a hole through the slab and removes a small amount of material underneath to create a suction pit. A PVC pipe is sealed into the hole and runs to a fan outside the living space. The fan runs all the time, and the pipe vents above the roofline.
A gauge on the pipe shows that the fan is pulling suction. When the liquid in the gauge is uneven, the system is working as designed.
Choosing the Suction Point and Pipe Route
Where the pipe goes is the part homeowners care about most. A suction point in an unfinished utility area, near an outside wall, is often the simplest choice. From there, the pipe can run through a closet or chase to the attic, or out through the rim joist and up the exterior wall.
The contractor looks at both options during the estimate. Interior routes keep the pipe out of sight from the street but need a clear path through the floors above. Exterior routes are often simpler and keep the fan outside, though the pipe is visible on the side of the house.
The contractor may also run a simple test by drilling a small hole and checking how air moves under the slab. That helps decide whether one suction point is enough or whether the house needs another.
Sealing That Supports the System
Suction works best when the slab is reasonably tight. Large cracks, gaps where the floor meets the wall, open floor drains, and an uncovered sump pit can let house air leak into the system and weaken it.
During the install, the contractor seals the openings that matter most. That may include caulking larger cracks, sealing around pipes that pass through the slab, and fitting an airtight lid on the sump. Sealing alone does not lower radon very much, but it helps the fan do its job.
The written quote should say which sealing work is included. If you plan to finish the basement later, mention it, because the pipe location and the cracks you can reach now may be covered up after the walls go in.
Get a Sub-Slab System Planned Right
For most York homes with a basement or slab, a sub-slab system is the dependable choice. Knowing the steps ahead of time takes much of the stress out of the process. Every home is a little different, and a short visit is the fastest way to learn what yours needs. Having the plan in writing makes the decision easier and the follow-up simpler. Call us and we will connect you with a local contractor for a written quote. You will see where the suction point, pipe, and fan would go before you decide.
Frequently Asked Questions
How does sub-slab radon mitigation work in a York basement?
A hole is drilled through the basement floor, a small pit is formed underneath, and a sealed pipe connects that pit to a fan outside the living space. The fan creates suction under the slab, pulling radon out and venting it above the roof. A gauge on the pipe shows the system is working.
Will finished flooring need to be opened for suction points?
Usually not much. Contractors try to place the suction point in an unfinished area such as a utility room or storage space. If the whole basement is finished, a small section of flooring may need to be cut, and the contractor will explain where and how it will be closed back up.
How is suction confirmed after a sub-slab install?
The contractor reads the manometer on the pipe once the fan is running, and may check suction at small test holes away from the main pit. Those readings show the system is pulling under the slab. A short-term radon retest afterward confirms the level inside the home has come down.