Middle Tennessee gives us four real seasons, a lot of pollen, and enough summer humidity to keep mold, mildew, and algae happy year round. That combination means exterior surfaces here get dirty faster than they do in drier parts of the country.
The short answer: once a year for most homes
For the average Franklin or Brentwood home, a full exterior soft wash once every 12 months keeps siding, soffits, and gutters clean without letting organic growth get a foothold. Homes under heavy tree cover, on north-facing lots, or near water usually need it every 8 to 10 months.
Surface-by-surface schedule
- Siding and soffits: every 12 months (8-10 months in heavy shade).
- Driveways and sidewalks: every 12-18 months, or annually if you park vehicles that drip.
- Roof: every 2-3 years, and only with a low-pressure soft wash — never a pressure washer.
- Decks and fences: every 12 months, right before you reseal or restain.
- Pavers: clean annually, reseal every 3-5 years.
Signs you're overdue
Don't wait for the calendar if you see green or black streaking on siding, dark spots spreading across shingles, a driveway that has gone from gray to brown, or slick spots on walkways and pool decks. Those are all organic growth, and organic growth keeps eating into the surface until it's removed.
Why timing matters more than you'd think
Mold and algae don't just look bad — they hold moisture against the surface. On siding that means faster paint failure. On concrete it means freeze-thaw damage in January. On a roof it means shingle granule loss and a shorter roof life. Washing on schedule is almost always cheaper than replacing what didn't get washed.
Best time of year in Tennessee
Spring and early fall are ideal. Spring clears off the winter's mildew and the pollen wave, and fall gets leaves, sap, and summer growth off before the first freeze. That said, we wash year-round here — anything above about 40 degrees works fine.