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Crawl space moisture in Royal Oak homes

Updated October 19, 2026 · referral service, not a contractor

Royal Oak crawl spaces are mostly under additions: the 1940s rear kitchen bump-out, the 1970s family room, the newer great room on a bungalow. They're shallow, often vented, and sit on the same sandy soil with a high water table as the basement next to them. The usual fix is a sealed vapor barrier plus drainage into the existing sump; the deluxe fix is full encapsulation.

Why the addition is damper than the basement

The original basement got footing drains (or at least a floor drain). The addition's crawl space often got neither: a few vents, bare dirt, and joists a foot or two above it. In spring the water table in Thetford-type sandy soil can come within a couple of feet of the surface, and that moisture evaporates straight into the framing. Vents make it worse in summer by letting humid air condense on cool joists.

Fixes, cheapest to most complete

1. Grading, downspout extensions, and closing vents in summer.
2. A heavy polyethylene vapor barrier over the soil, seams taped, edges run up the wall.
3. Perimeter drain in the crawl tied to the basement sump.
4. Encapsulation: reinforced liner sealed to the walls, foam board on the walls, vents sealed, a dehumidifier. The crawl becomes part of the conditioned house.

One thing to check first

Where the addition meets the old foundation, there's often a gap or a cold joint that leaks into the basement side. Have the contractor look at that seam from both sides before pricing anything.

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Name Phone Email (optional) ZIP code What's going on?Seepage at the floor/wall seamWater through a wall crackLeaking Michigan basement / stone or brick wallSump pump failed or short-cyclingFloor drain backs up in stormsDamp crawl spaceSomething else Details (optional) Request my estimate

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Sources

• USDA NRCS Soil Data Access, map unit components at Woodward/13 Mile (Vinsetta Park), Crooks/14 Mile (Northwood) and Campbell/11 Mile, queried Oct 19 2026 — https://sdmdataaccess.sc.egov.usda.gov/