Black Diamond's wooded lots and lakeside neighborhoods stay damp for months, and that moisture shows up indoors as mildew on window frames, bathroom ceilings and closet walls. Light growth on hard surfaces can be cleaned at home, while larger patches or anything soaked into drywall or carpet calls for a professional. Call the number on this page to be connected with a local mold remediation company in Black Diamond.
Why foothill homes grow mildew
Black Diamond is a former coal-mining town in the Cascade foothills, about 26 miles southeast of Seattle, and locals call it the "Town of Many Lakes." Lake Sawyer, at 286 acres one of King County's largest natural lakes, sits at its edge, with Lake 12 and Ginder Lake nearby and the Green River Gorge a short drive away. Homes under big conifers or close to the water get little sun through the wet season, so exterior walls and window glass stay cold while the air around them stays humid. Inside, that turns into condensation on windows in the morning, mildew in the corners of bedrooms on north-facing walls, and a stale smell in closets that rarely open.
New construction isn't immune. A lot of the town's recent growth is in the Ten Trails master-planned development, whose first residents moved in during 2018. Newer, tighter houses hold moisture well, so mildew can appear on window sills and in bathrooms if exhaust fans aren't used or are undersized. If repairs after cleanup involve new drywall or framing, City of Black Diamond Community Development handles building permits.
Clean it yourself or call a pro
| Situation | Homeowner cleanup | Professional cleanup |
|---|---|---|
| Size | Under about 10 sq ft on hard surfaces | Over 10 sq ft, or several rooms |
| Material | Tile, glass, sealed trim, painted surfaces that wipe clean | Drywall stained through, carpet, ceiling tile, soft wood |
| Moisture source | Obvious and fixable, such as a fan left off | Unknown, hidden or inside a wall |
| Pattern | First time you've seen it | Returns within weeks of cleaning |
The 10 square foot guide comes from EPA and Washington DOH.
Signs to look for
- Black dots in the corners of window frames and along the bottom of the glass
- Gray film on bathroom ceilings above the shower
- White or green bloom on leather, shoes or luggage stored in closets
- Musty odor in a guest room after a few weeks with the door shut
Seasonal notes
Mildew tends to peak late in the wet season, after months without a good drying spell. Cleaning in fall and again in early spring, keeping the heat at a steady setting instead of letting rooms go cold, and cracking a window on drier days all help. Summer, the driest part of the Puget Sound year, is a good time to repaint cleaned surfaces once they're fully dry and to replace weak bathroom fans.
Mold & Mildew Cleanup questions in Black Diamond
Will a dehumidifier stop mildew?
Is mildew the same thing as mold?
Why does mildew show up on my windows every winter?
Should mildewed carpet, curtains or ceiling tiles be thrown out?
More mold services in Black Diamond
Mold & Mildew Cleanup nearby
Sources
Last updated: