Mold vs. Mildew: How to Tell the Difference (and When to Call a Pro)
If you've found a dark patch in your shower or a musty smell in a closet, the first question is whether you're looking at mildew (usually a surface-level nuisance) or mold (which can mean a deeper moisture problem). They're related, but the right response is different.
What mildew typically looks like
Mildew usually appears as a flat, powdery growth — white, gray, or light yellow — on damp surfaces like shower tile, window sills, or fabric. It tends to stay on the surface and is often manageable with routine cleaning and better ventilation.
What mold typically looks like
Mold tends to be fuzzy or slimy in texture and appears in darker colors — black, green, or dark blue — and it can grow beneath the surface of porous materials like drywall, wood, and insulation, not just on top of them. A musty smell with no visible growth can also indicate mold growing somewhere unseen.
Signs it's time to call a professional
- Visible growth covering an area larger than roughly 10 square feet
- Mold that followed a flood, burst pipe, or other water event
- A persistent musty odor with no visible source
- Growth returning repeatedly after you've cleaned it yourself
- A household member experiencing symptoms that seem linked to a specific room
“The key to mold control is moisture control.”
That's the real takeaway: cleaning visible growth without fixing the moisture source — a leak, poor ventilation, or high humidity — usually means it comes back. A remediation contractor should address both the growth and the cause, not just the surface you can see.
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