What is the best soffit cleaning solution?
Short answer. For most soffits, a mild solution of dish soap and water handles dirt, and an oxygen bleach solution or a diluted household bleach mix handles mildew, applied with a soft brush and rinsed at low pressure. Avoid blasting water upward into vented soffit, which pushes water into the attic and insulation.
Cleaning by material
- Vinyl: soap and water or an oxygen bleach solution. Skip solvents and abrasive pads, which dull the finish.
- Aluminum: mild detergent. Strong alkaline cleaners can streak painted aluminum.
- Painted wood or fiber cement: gentle detergent and a soft brush. Scrubbing hard can lift paint and expose wood to moisture.
Doing it safely
- Test any solution on a hidden spot first.
- Wet plants below before and after if you use bleach, and keep the mix mild.
- Use an extension pole from the ground where possible, and never work on a ladder near power lines.
- Rinse with a garden hose, not a pressure washer aimed upward at vents and panel seams.
What the stain is telling you
- Even gray or black film on shaded sides: mildew from Georgia humidity. Cosmetic.
- Brown or tan streaks starting at the roof edge: water getting behind the gutter or over the fascia, often from a missing drip edge or overflowing gutters.
- A stain at one spot that keeps returning: often a roof edge leak or a gutter seam.
- Sagging or soft panels: rot in the wood behind them.
If staining points to water, cleaning will not fix it. Check drip edge explained and gutter sizing and guards, and see black streaks and algae for the roof itself.