Mildew-resistant paint can inhibit growth on the paint film, but it does not sterilize a dirty wall, fix a sprinkler that keeps the wall wet, or make existing mildew safe to paint over. In Florida, mildew resistance is a useful coating property—not a substitute for cleaning and moisture control.
What “Mildew Resistant” Usually Means
Manufacturers commonly formulate exterior paints with agents intended to inhibit mildew growth on the cured coating film. Sherwin-Williams notes that even mildew-resistant paints can eventually develop mildew under favorable conditions and recommends cleaning/maintenance in environments where growth is persistent.
Never Use New Paint as the Mildew Cleaner
Behr and Sherwin-Williams both instruct users to remove mildew before repainting. Mildew, dirt and biological residue form a contaminated surface that can interfere with adhesion and can reappear through the new finish.
Look for the Moisture Pattern
- Shaded north-facing walls stay damp longer.
- Sprinklers can repeatedly wet one band of masonry.
- Leaking gutters, roof edges, AC condensate and failed sealant can keep areas wet.
- Dense landscaping can reduce sun and airflow.
If mildew returns quickly in the same place, improving the wetting/drying condition may do more than changing paint brands.
Cleaning Safety
Follow the labeled cleaner and protective-equipment instructions. Never mix bleach or sodium-hypochlorite cleaners with ammonia, acids or other incompatible chemicals.