Activating a passive radon system in York, PA

What is a passive radon system?

A passive radon system is a sealed vent pipe that runs from the gravel under the floor slab up through the house and out above the roof, installed during construction and running without a fan. Warm air rising inside the pipe draws some soil gas out, which is cheaper than a fan and weaker.

The pipe is one of five features the EPA lists for radon-resistant new construction, which are listed below.

1. Gravel. A layer of clean, coarse gravel about four inches deep below the slab, so suction can spread under the floor.
2. Plastic sheeting. Heavy duty polyethylene over the gravel, which keeps soil gas from rising straight into the house.
3. Vent pipe. A 3-inch or 4-inch solid PVC pipe running vertically from the gravel layer through the house and the roof.
4. Sealing and caulking. Openings, cracks and crevices in the concrete floor sealed with polyurethane caulk.
5. Junction box. An electrical outlet in the attic, ready for a fan if a radon test later shows the house needs one.

Source: EPA, radon-resistant construction basics and techniques.

How do you know if your house has a passive radon pipe?

A passive radon pipe shows itself in the basement as a capped white PVC pipe that comes up out of the concrete slab and runs straight up into the floor above instead of connecting to a drain. Follow it upward and it continues through a closet or chase to the attic and out through the roof, often with an electrical outlet beside it in the attic.

Owners often do not know the pipe is there, and the record suggests plenty of York County houses have one: the DEP register lists 1,378 passive systems activated in York County since 1987. The builder's paperwork or a home inspection report can confirm it, and a radon contractor will recognize it in one look.

Does a passive radon system work without a fan?

A passive radon system may lower radon without a fan, but only a radon test tells you whether it lowered it enough. The pipe depends on warm air rising inside it, which pulls less than a fan, and that is why the EPA's design keeps an outlet in the attic for a fan should a test show one is needed.

The York County record holds a small group of passive systems installed and tested by certified contractors: 65 with a reading before and after averaged 20.6 pCi/L before and 0.91 after. That is a selected group rather than a verdict on every builder's pipe, and the reading from your own house is the one that decides. The page on testing for radon in York County covers when and how to test.

How much does it cost to activate a passive radon system?

Activating a passive radon system cost an average of $770 in York County across 143 jobs recorded by the Pennsylvania DEP from 2024 to 2026. Building a full sub-slab system from scratch averaged $1,279 over the same years, so an existing pipe saved about 40 percent.

Source: PA DEP radon mitigation dataset on the PA Open Data Portal, retrieved 21 September 2026.

An activation quote should cover the fan, the wiring, a manometer and the system label. Ask whether the post-mitigation test is included, because that is where otherwise similar quotes differ. The fan then runs continuously, at about $4.57 a month for a 50 watt fan at the Pennsylvania average electricity rate, as set out on the page about radon mitigation cost in York County.

How is a passive radon system activated?

A passive radon system is activated by fitting a fan into the existing vent pipe outside the living space, wiring it, adding a warning device and testing the result. The five steps below are the usual order.

1. Test first. The EPA recommends fixing a house at 4 pCi/L or more and suggests considering it between 2 and 4 pCi/L.
2. Fan fitted in the pipe. The fan goes into a vertical section of the existing pipe in the attic or outside. Under 25 Pa. Code 240.308 it may not sit below grade, in a window well, in conditioned space, or in a basement or crawl space under heated or cooled rooms.
3. Wiring. The fan is wired to the attic outlet or a new circuit to local electrical code, which the EPA requires for every active system.
4. Warning device. A manometer or other warning device goes on the pipe, so you can see that the fan is pulling.
5. Post-mitigation test. A radon test once the fan has run for at least 24 hours and within 30 days, the window the EPA gives for a new system.

Sealing the sump lid and any open cracks at the same visit helps the fan draw from under the slab, because suction only works under a floor that is reasonably tight. What happens when that fan eventually wears out is covered on the page about radon fan replacement.

How well does an activated passive system work?

Activated passive systems are among the best performers in York County: across 602 activations with a reading before and after, radon fell from an average of 22.9 pCi/L to 1.15, a cut of 95.0 percent, and 98.8 percent of the houses ended below the action level.

The reason is simple: the gravel layer, the sheeting and the sealed pipe were designed in during construction, so the fan draws from a prepared space rather than from a hole cut into an existing slab. How the other system types compare is set out on the page about how a radon mitigation system works.

Can you activate a passive radon system yourself?

Adding a fan to a passive pipe is the smallest radon job there is, but whether Pennsylvania's certification requirement reaches an owner working on their own house is a question for the PA DEP Radon Division on 800-237-2366, not for a guide. On a rental or anyone else's house, the work requires DEP certification.

If you do the work yourself, the same rules apply as for a contractor: the fan stays outside the living space, the wiring follows local electrical code, a manometer goes on the pipe and the house gets a fresh radon test. The wider picture is on the page about doing radon mitigation yourself.

Common questions about passive radon systems