Radon Testing & Mitigation in Wilmette
Wilmette has the oldest housing stock on this stretch of the North Shore — a median build year of 1957, with nearly a third of homes predating 1940. Old foundations are exactly where radon finds its openings. We test and fix them, with licensed installs and verified results.
Pre-war foundations and the radon math
Nearly one in three Wilmette homes — 28.6% — was built before 1940, by far the highest pre-war share among the neighboring suburbs, and the village's median home dates to 1957. Nearly three-quarters of the housing stock predates 1970. That's eighty-plus years of foundation settling in the oldest homes: hairline cracks in slabs and walls, original drain systems, coal-era floor penetrations, and sump pits retrofitted long after the house was built. Every one is a potential soil gas pathway, and none of these houses had radon on anyone's mind at construction — Illinois didn't require radon-resistant construction in new homes until June 2013.
The county-level numbers say the risk is real: Cook County maps as a moderate EPA radon zone, yet nearly 30% of county homes tested by licensed professionals measure at or above the 4.0 pCi/L action level. In a village where the housing is this old and this large — Wilmette's median 7.6 rooms per home is the biggest on this part of the shore, and finished basements are standard — the sensible move is a cheap, definitive 48-hour test rather than an assumption either way.
Homes worth protecting, owners who stay
Wilmette is a village people settle into: 87.9% of occupied homes are owner-occupied, the highest rate of the neighboring suburbs. When you're going to breathe a basement's air for twenty years, the case for a one-day mitigation install at $800 to $2,500 makes itself. In pre-war homes, routing gets a little more thought — plaster walls, vintage trim, and stone or block foundations reward an installer who has done this on old housing stock before — and route and appearance get agreed on before anything is drilled. Every install we arrange is by an Illinois-licensed professional, finishes with the state-required tag on the vent pipe, and gets a verification test to prove the number dropped.
Permits and paperwork
Building permits in Wilmette run through the village's Community Development Department on Wilmette Avenue, and the village is known for careful plan review on work touching older homes. That's handled inside the quote, not an extra. If the radon question is coming up because you're buying or selling — the most common reason it does — our real estate testing page walks through the 48-hour transaction test and how mitigation gets negotiated when a result comes back high.
A 1920s foundation deserves a 2026 test.
Call (224) 362-4440