Radon Testing in Dunlap, IL
Radon testing and mitigation in Dunlap, IL, including activating the passive stubs left in newer District 323 area homes and well water testing.
The most common radon conversation in Dunlap starts with a homeowner who found a capped white pipe running up through a closet or out of the garage ceiling and wants to know what it is. In a house built in the last decade or so, that is usually a passive radon stub: a vent pipe set into the gravel under the slab during construction, run up through the roof, and left to work on its own by convection.
Passive is not the same as effective. It moves some soil gas some of the time, and on plenty of Dunlap houses it does enough. On plenty of others it does not, and the only way to separate those two groups is to test. The good news is that when a stub is present and a test comes back high, the fix is short work: the hard part, the pipe through the structure, is already done.
The other half of Dunlap is the acreage. Once you get out past the village limits into unincorporated Peoria County, houses are on private wells, and well water carries its own radon question that a municipal supply does not.
Serving all of Dunlap, IL and the surrounding Peoria area.
Dunlap sits on the upland north of Peoria along Route 91, and it has grown steadily as families move in for the District 323 schools. Much of the housing is newer than the metro average, which means a meaningful share of it was built after Illinois began requiring passive radon-resistant features in new residential construction. It also means a lot of Dunlap homes have a capped pipe in a closet or garage that nobody has ever explained to the owner, and the unincorporated Peoria County acreage around the village is on private wells.
Passive builder stubs evaluated and activated with a fan when testing calls for it
Newer District 323 area homes tested rather than assumed to be fine
Well water radon addressed for unincorporated Peoria County properties
Straight explanation of what that capped pipe in your closet actually does
Passive Stubs That Were Never Turned On
Illinois has required passive radon-resistant features in new residential construction since 2013, and a good share of the newer Dunlap subdivisions went up under that requirement. What a builder installs is a rough-in: gravel and a vapor barrier under the slab, a pipe teed into that gravel, and a run up through the house and out the roof. There is no fan, no manometer, and no test result attached to it.
Turning a passive stub into an active system usually means adding an inline fan in the attic or on the exterior run, sealing what needs sealing at the slab, adding a pressure gauge so the system reports on itself, and retesting to confirm the number moved. It is a much smaller job than starting from a bare slab, which is the whole point of the rough-in existing.
- •Passive stub, capped pipe, and rough-in all describe the same thing
- •No fan means no guarantee, only a head start
- •Adding a fan is short work when the pipe is already run
Well Water on the Unincorporated Acreage
Outside the village, the larger lots along the county roads north and west of Dunlap are typically served by private wells. Groundwater picks up dissolved radon from the same rock that produces soil gas, and it releases into the air whenever the water gets agitated by a shower, a dishwasher, or a washing machine. That is a separate exposure path from anything coming through the foundation, and a sub-slab system does not touch it.
If you are on a well and your air test is stubbornly higher than the foundation seems to justify, water is worth ruling in or out. Nobody on a municipal supply needs to think about this, which is exactly why it gets missed on the acreage.
Why a Newer Dunlap House Still Gets Tested
Buyers moving into Dunlap for the schools often assume a house built in the last fifteen years is a low-risk house. Construction age changes the entry points, not the soil. A newer slab has fewer settling cracks than a hundred-year-old foundation, but it still has plumbing penetrations, a cold joint at the perimeter, and in many cases a sump pit, and the stack effect still pulls soil gas upward through all of it.
Test the house you are actually buying. A neighbor's result on the next street, even in the same subdivision from the same builder, is not a substitute, because soil gas concentration varies over short distances and no two lots were graded and backfilled identically.
Frequently Asked Questions
There is a capped white pipe in my Dunlap closet. What is it?
In a newer home that is almost certainly a passive radon stub, installed during construction and running from the gravel under your slab up through the roof. It is a rough-in, not a finished system. It has no fan and no gauge, so it has never told anyone whether it is working. A test answers that, and if the number is high, adding a fan to the existing pipe is a short job.
My house was built after the radon-resistant construction requirement. Am I covered?
You have a head start, not a result. The requirement covers passive features during construction, and passive systems reduce levels in some houses and not others depending on soil, slab, and how the home is operated. Nothing in that requirement includes a test, so the only way to know where your house landed is to measure it.
We are on a well outside the village. Should we test the water too?
It is worth doing, especially if your indoor air number is higher than your foundation seems to explain. Dissolved radon in well water releases into the air during showers and appliance use and also matters as a direct ingestion exposure. It is a separate system from a sub-slab fix, handled with aeration or carbon filtration depending on the level.
Our subdivision neighbor tested low. Do we still need to test?
Yes. Same builder, same street, same year, and the numbers still diverge, because soil gas concentration changes over short distances and every lot was excavated and backfilled a little differently. The only address a test result speaks for is the one it was run at.
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