How often to wash each surface — a Middle TN schedule

What makes Middle Tennessee different

Humidity and shade run this schedule. Coffee, Bedford, and Franklin counties sit in a humid subtropical zone with warm summers, mild winters, and enough rain year-round to keep algae and mildew active most of the year.

The practical effect: a north-facing wall or a shaded driveway in Manchester grows algae 2–3× faster than the same surface in a dry western climate. Which is why 'once every few years' — the schedule you'd hear in Arizona — doesn't apply here.

Climate factors that set the local cadence

Four local conditions do most of the work in deciding how often a surface needs attention. Understanding them makes the schedule below make sense — and lets you adjust it for your specific lot.

• Humidity. Middle Tennessee averages 70–80% relative humidity from May through September. Algae and mildew are basically continuously active on any surface that stays damp for more than a few hours.
• Pollen. A heavy tree-pollen wave hits in April (yellow-green film on everything) and a lighter ragweed wave hits in September. Pollen isn't just visual — it becomes food for algae once it settles and gets wet.
• Mold and mildew. Both establish on any organic film — pollen, dirt, tree sap — that sits on siding, decking, or shaded concrete. Once colonized, they hold moisture longer, which speeds their own growth. This is why 'the green side' of the house gets greener faster year over year if it's not washed.
• Tree coverage and shade. North-facing walls, walls under a heavy canopy, and any surface within 5 feet of foliage stay damp longer. Rule of thumb: for every side of the house with dense tree cover, subtract about 3 months from the recommended wash interval.
• Lot drainage. Homes on low-lying lots, at the bottom of a slope, or near creeks and drainage ditches sit in more ambient moisture. They typically need siding cleaned every 6–9 months instead of the standard 12.

House siding — once a year

Annual is the default for most homes in the area. Twice a year if the house is heavily shaded (tree canopy on 3+ sides), sits in a low-lying area, or has north-facing walls that stay damp.

Signs it's time: green tint on the shaded side, black spotting on the soffits, dust-and-pollen film that a rain doesn't rinse off. Once you can see the algae, the biological growth is already deep in the surface — the longer it sits, the more aggressive the wash needs to be.

Concrete driveways and walkways — every 12–18 months

Concrete is porous. Dirt, algae, and iron staining sink in and get harder to lift the longer they sit. On a 12-month cycle, a driveway looks new after each wash. Push it past 24 months and the algae has usually stained the surface enough that a wash is a big improvement but not a full reset.

If your driveway is shaded, cut the interval to 12 months. If it gets full sun and mostly light dust, 18 months is fine.

Wood decks — annually, plus stain every 2–3 years

A wood deck should get a light annual wash to knock back mildew and lift debris. That extends the life of the stain and the boards themselves.

Every 2–3 years, that annual wash becomes a pre-stain wash — a slightly different job that uses a brightener rinse to open the grain and prep for a fresh stain or sealer coat. Composite decks (Trex, TimberTech) need washing on the same schedule but never need staining.

Fences — every 1–2 years

Wood privacy fences pick up algae on the shaded side within a year or two. Annual washing keeps it under control; every two years is the outer edge. Vinyl fencing is on the same schedule as vinyl siding — annual soft-wash.

If a wood fence is unsealed, expect gray weathering to set in within 3–5 years regardless of how often it's washed. Sealing or staining slows that dramatically.

Patios (paver, stamped concrete, flagstone) — every 12–24 months

Patios collect food, drink spills, sunscreen, and shade-driven algae. Once a year is ideal for entertaining patios; every other year works for lightly-used ones. If moss is establishing between pavers, don't wait — moss holds moisture that eventually rots the joint sand and freezes/thaws the pavers out of level.

Gutter faces — as needed

Gutter face tiger stripes aren't on a strict schedule — they appear when they appear, usually 3–7 years after installation. Once you can see them from the street, they only get worse. Best value is to bundle a gutter brightening onto a house wash so the setup cost is shared.

Full quick-reference schedule

• Siding: annually (twice/year if heavily shaded).
• Driveway / walkway: every 12–18 months.
• Wood deck: annually; pre-stain wash every 2–3 years.
• Composite deck: annually.
• Wood fence: every 1–2 years.
• Vinyl fence: annually.
• Paver or stamped-concrete patio: every 12–24 months.
• Gutter face: as needed (typically every 3–5 years).
• Roof: every 3–5 years — referred out to a soft-wash roofing specialist.