Central Ohio homeowners ask this constantly, and if you search it you will get answers ranging from every 12 months to every four years. That spread is not because anyone is lying — it is because those recommendations are answering slightly different questions. This guide gives you a straight answer for a Columbus-area home, then explains exactly why the published advice disagrees so you can judge it for yourself.
The short answer
- Most homes: Every 1–2 years
- Shaded or wooded lots: Annually or every 12–18 months
- Sunny, exposed homes: Every 2–3 years (sometimes longer)
- Homes near a creek, pond, or on a damp, low-lying lot: Annually
If you only remember one thing: in this climate, the shade on your walls matters more than the calendar. Two identical houses on the same street can genuinely belong on different schedules.
Why you will see four different answers to this question
Search this and you will find confident, specific, conflicting intervals. Here is the range of guidance published across the exterior-cleaning market and national home-maintenance sources, and what each recommendation is usually assuming. These are other companies' and publishers' figures — general market guidance, not our quoted schedule.
| Published interval | What that recommendation usually assumes |
|---|---|
| Every 12–18 months | A shaded or tree-covered lot, or a homeowner whose goal is that the siding never visibly discolours at all. Common in humid regions and on north-facing elevations. |
| Every 1–2 years | The general-purpose answer for a typical suburban home with mixed sun and shade. This is the one that fits the most Central Ohio houses. |
| Every 2–3 years | Usually framed around protecting the material rather than appearance — washing often enough that algae never damages the surface, accepting some visible film in between. |
| Every 2–4 years | Typically assumes an open, sunny, well-drained lot, and often reflects a drier climate than ours. The long end of this range rarely holds up on a shaded Ohio wall. |
The five real reasons the advice disagrees
- They are measuring different goals. "How often to keep it looking clean" and "how often to keep algae from degrading the surface" are two different questions with two different answers. The first is always the shorter interval. Most articles never say which one they are answering.
- They assume different exposure. A recommendation written for an open, south-facing lot is simply wrong for a house under a mature canopy. Shade slows drying, and organic growth needs moisture and time far more than it needs dirt.
- Climate assumptions travel badly. A national interval blends Arizona and the Gulf Coast into one number. Central Ohio sits at the humid end of that average, so figures written for a national audience tend to run optimistic here.
- The previous wash was not necessarily the same service. This is the biggest hidden variable. A true soft wash applies a cleaning solution that kills algae and mildew at the root. A pressure rinse only blasts the visible growth off the surface and leaves the organism behind, so it re-establishes within months. If your house was rinsed rather than soft washed, no interval will hold.
- Material and colour change what you notice. Growth shows earliest on light vinyl and painted surfaces and hides longer on brick, dark siding, and textured stucco. The growth rate is the same; the point at which you see it is not.
One more thing worth saying plainly: interval advice is rarely neutral. A longer interval supports a low-maintenance sales story; a shorter one supports more frequent bookings. Read every recommendation with that in mind — including ours. That is precisely why the table below is built around your conditions rather than a single number.
Find your house: a practical schedule
| Your situation | Reasonable interval | What to watch |
|---|---|---|
| Open lot, full sun most of the day, few mature trees | Every 2–3 years | South and west walls stay clean longest; check the north side anyway. |
| Typical suburban lot, mixed sun and shade | Every 1–2 years | North and east elevations, and anywhere a downspout discharges. |
| Mature tree canopy, wooded lot, or heavy shade on one elevation | Every 12–18 months | Green film on shaded walls; moss at grade and on the roof's shaded slopes. |
| Backs to a creek, pond, ravine, or sits low and stays damp | Annually | Persistent dampness at the lower courses of siding; mildew in shaded corners. |
| Last cleaning was a pressure rinse, not a soft wash | Expect regrowth inside a year regardless | Streaks returning in the same pattern as before — a sign the algae was never killed. |
| Under an HOA with an appearance covenant | Whatever keeps you ahead of a notice — usually annually | The first thin green haze, not obvious dirt. See our guide to HOA siding letters. |
What drives the schedule
- Shade and tree cover — less direct sun means slower drying and faster algae/moss growth. This is the single strongest factor in Central Ohio.
- Orientation — north and east sides often show growth first, because they get the least drying sun.
- Siding material and color — some materials and lighter colors make growth more visible.
- Proximity to water or low areas — higher humidity accelerates organic growth.
- Drainage and gutters — an overflowing gutter or a downspout dumping against the wall creates a permanently damp strip that will regrow long before the rest of the house.
- Previous maintenance — homes that have been consistently maintained usually need less aggressive work, and each wash is faster and gentler than a restoration.
Why Central Ohio is harder on siding than the averages suggest
Our specific combination of conditions is what pulls local intervals toward the shorter end:
- Humid summers. Warm, humid air plus shade is the ideal environment for the algae and mildew that discolour siding.
- Heavy spring pollen. Pollen films the house and then feeds organic growth once the rain sets in.
- Mature tree canopy. Much of the older housing stock in Worthington, Gahanna, Lewis Center, and Powell sits under exactly the kind of shade that keeps walls damp for hours after rain.
- Fall leaf litter. Leaves trapped behind shrubs and in gutters hold moisture against the house well into winter.
- Freeze-thaw cycles. Repeated freezing works moisture into porous surfaces and open joints, which is why letting growth sit for years is a material problem and not only a cosmetic one.
The seasonal side of this — which months are actually best to schedule — is covered in our guide to the best time of year to wash your house in Central Ohio.
Signs it is time, regardless of the calendar
Don't wait for the house to look obviously dirty. Common early indicators include:
- Black or green streaking on siding (especially north and east sides)
- Moss or algae on roof edges or in valleys
- Slippery or discolored decks and patios
- Visible mold or mildew near ground level or in shaded corners
- A chalky or filmy feel when you run a hand along the siding
- Growth returning in the same streak pattern within months of the last cleaning — the clearest sign the previous job rinsed rather than treated
Your roof is on a different clock
Siding and roofs do not need cleaning on the same schedule, and bundling them by default is a mistake in both directions. Roof algae — the black streaks caused by Gloeocapsa magma — develops on shaded slopes and often becomes visible before siding growth does, particularly on north-facing planes under trees. Many Central Ohio roofs do well on a 2–4 year cycle while the siding beneath them is on 12–18 months.
Roof cleaning must be low-pressure work: see roof soft washing for the method, whether cleaning affects your shingle warranty, and typical roof cleaning costs in the Columbus area. When the two schedules do line up, cleaning both on one visit is meaningfully cheaper than two separate trips.
Maintenance tips to stretch the time between washings
- Keep gutters and downspouts clear so water doesn't overflow onto siding.
- Trim trees and shrubs to increase sunlight and airflow around the house.
- Address any grading or drainage issues that keep areas damp.
- Redirect downspout discharge away from the wall rather than against it.
- Pull mulch and dense plantings back a few inches from the siding so the lower courses can dry.
- Consider annual inspections — catching light growth early is much easier than waiting for heavy buildup.
The bottom line
For most Columbus-area homes, every 1–2 years is the right planning assumption — shorter if your walls sit in shade, longer if they sit in sun. But the interval matters less than the method: a house that is properly soft washed stays clean for its full cycle, while a house that was merely pressure-rinsed will re-streak no matter what the schedule says. Ask any contractor what solution they apply and what pressure they use before you ask how often they will come back.
Homes kept on a predictable cycle (every 12, 18, or 24 months) hold a far more consistent appearance, and each visit is lighter and gentler because growth never gets out of hand. Typical pricing for each surface is in our Central Ohio pressure washing cost guide.
If your association got there before you did and you are holding a notice with a deadline on it, our guide to responding to an HOA letter about your siding covers what the letter means and how to close it out.
Not sure which column of the table your house belongs in? Get a free, no-obligation estimate and we'll assess your exposure, siding material, and current growth, and tell you the interval your specific property actually needs.