“Mildew” and “mold” are both fungi. What matters for you is where it is growing and how deep it goes. Here’s a practical way to tell a cleaning job from a remediation job.
Mildew usually…
- Is flat and powdery, gray, white or light brown.
- Sits on the surface of non-porous or sealed materials: tile, grout, glass, tub caulk, shower curtains.
- Wipes off with a household cleaner and stays gone for a while if you ventilate.
Mold that needs remediation usually…
- Is fuzzy, slimy or blotchy, black, green, or sometimes orange or pink.
- Grows in porous materials: drywall, plaster paint, wood, carpet, insulation.
- Comes back in the same place after cleaning or painting.
- Comes with a musty smell, stains, bubbling paint or soft drywall.
What about “toxic black mold”?
You can’t identify a mold species by color. Many dark molds aren’t Stachybotrys, and some light ones are problems too. For health and property, the advice is the same: indoor mold growth should be removed and the moisture fixed. If you need the species identified, an independent mold assessor can sample it. We don’t test (here’s why).
A quick test you can do
Dab a drop of diluted household bleach on the spot (with ventilation and gloves). If it lightens within a minute or two and doesn’t come back after cleaning, it is likely surface mildew. If it returns, or the material underneath is soft or stained, there is moisture in the material.
When to call
If it’s bigger than a doormat, keeps coming back, or follows a leak, it’s a remediation job. Try our 60-second Mold Risk Check or send us photos.