Mildew smell in a basement or crawlspace-level room

Daylight basements and lower-level rooms in Puget Sound homes are notorious for a mildew smell that comes and goes with the weather. The carpet looks fine. The room smells like a wet towel.

The usual cause is moisture migrating up through the concrete slab into the carpet pad. Pad is foam; it holds moisture; mildew grows in it. The smell is strongest in the wet season and after the room has been closed up.

What cleaning does

Hot water extraction with an antimicrobial rinse and fast drying removes surface mildew and the organic matter it feeds on. Speed-drying with air movers is essential so we do not add moisture to the problem. This fixes the smell in most rooms for a season or more.

What it cannot do

If the slab is wet, the pad will get wet again. A dehumidifier running in the room, a vapor barrier under the pad (when the carpet is next replaced), or fixing exterior drainage are the long-term fixes. We will tell you honestly if the moisture reading in the pad suggests an ongoing water issue.

Area rugs

A rug on a damp slab develops mildew on the back. Lift a corner and look. That is an off-site wash, and we will pick it up.