Black Mold vs. Mildew: How Gresham Homeowners Tell Them Apart
Black mold and mildew get lumped together constantly, but they behave differently and call for different responses. Understanding which one you're looking at can save you a call you didn't need — or tell you it's time to make one.
What Mildew Actually Is
Mildew is a surface-level fungal growth, usually appearing as a flat, powdery patch that's white, gray, or light yellow. It typically grows on damp surfaces like shower tile, window sills, or fabric, and it stays on the surface rather than growing into the material underneath. Mildew is generally the easier of the two to manage — a household cleaner and better ventilation often keep it in check.
What Black Mold Actually Is
"Black mold" refers to fungal growth that appears dark in color and, unlike mildew, can grow into porous materials — drywall paper, wood, insulation, and grout — not just sit on top of them. It tends to show up where moisture has been present longer or more consistently: a slow leak, a chronically damp crawl space, or a bath fan venting into the attic instead of outside.
The Texture and Smell Test
Mildew usually looks flat and powdery and can often be wiped away, at least temporarily. Mold growing into a material tends to look raised, fuzzy, or slimy, and simply wiping the surface doesn't make it go away because the growth extends below what you can see. Both can produce a musty odor, but a persistent, strengthening musty smell — especially with no obvious surface growth — is more often a sign of mold hidden behind a wall or under flooring.
Why the Distinction Changes Your Response
Surface mildew on tile or a window sill is usually a homeowner-manageable cleaning task. Mold growing into drywall, wood framing, or insulation is a different job — the affected material typically needs to be physically removed, not just cleaned, and the moisture source needs to be found and fixed or the growth returns. If you're not sure which one you're dealing with, that uncertainty itself is worth a phone call.
When In Doubt, Ask
We inspect Gresham homes for exactly this distinction every week. Describe what you're seeing — the surface, the texture, whether it wipes off — and we'll give you a straight answer about whether it's a cleaning job or a remediation job.