If you’ve noticed dark streaks running down your roof, you’re not alone. Roofs across McKinney, Plano, Frisco, and the rest of Collin County develop the same black stains over time. The question most homeowners ask is simple: how often should I clean my roof?
The short answer: most North Texas roofs should be professionally soft washed every two to three years, and roofs with heavy shade or north-facing slopes may need cleaning every one to two years. Below, we explain why, what to look for, and how to keep your roof cleaner for longer.
Why North Texas Roofs Get Dirty
Those black streaks aren’t dirt. They’re a hardy, airborne algae called Gloeocapsa magma. Its spores travel on the wind and land on roofs, where they feed on the limestone filler in asphalt shingles. As the algae spreads, it forms a dark protective coating, which is why the streaks look black instead of green.
North Texas creates good conditions for it. Humid springs, heavy storms, and morning dew keep shingles damp. Mature trees in established neighborhoods shade roofs and drop leaves that hold moisture. North-facing roof slopes get the least sun, so they stay wet the longest and usually show streaks first.
Signs It’s Time to Clean Your Roof
- Black or dark gray streaks running down from the ridge or along the edges.
- Green moss or crusty lichen growing in shaded areas or around valleys.
- A blotchy, uneven color when you compare one side of the roof to another.
- An HOA letter asking you to address the roof’s appearance.
- Streaks spreading to gutters, fascia, or siding below the roofline.
If you see any of these, it’s a good time for a cleaning. The sooner algae is removed, the less time it has to spread and wear down your shingles.
What Affects How Often You Should Clean
Every roof is different. These are the biggest factors that decide whether yours needs cleaning every year or every few years:
- Shade: More shade means more moisture, and more moisture means faster algae growth.
- Roof direction: North- and east-facing slopes dry slower than south- and west-facing slopes.
- Nearby trees: Overhanging branches drop leaves and seeds and block sunlight.
- Gutters: Clogged gutters trap water along the roof edge.
- How it was cleaned last time: Soft washing kills algae at the root, so results last much longer than a quick rinse.
Recommended Cleaning Schedule for North Texas Homes
Here’s a general guide for most homes in our area. Your schedule may be shorter or longer depending on shade and conditions.
| Surface | Typical cleaning schedule |
|---|---|
| Roof (sunny, few trees) | Every 2–3 years |
| Roof (shaded or north-facing) | Every 1–2 years |
| House siding, brick & trim | Every 12–18 months |
| Gutters | 1–2 times per year |
| Driveway & walkways | Once a year |
| Fences | Every 1–2 years |
Why You Should Never Pressure Wash a Roof
It’s tempting to grab a pressure washer, but high pressure can knock the protective granules off asphalt shingles, force water under them, and shorten the life of your roof. The Asphalt Roofing Manufacturers Association recommends low-pressure cleaning methods rather than pressure washing.
That’s why we use soft washing. We apply a professional, biodegradable cleaning solution at low pressure, let it break down the algae, then rinse. It cleans without damaging your shingles, and because it kills the algae instead of just blasting the surface, the results last much longer. We also pre-wet and protect your plants and landscaping before and after we work.
How to Keep Your Roof Cleaner for Longer
- Trim tree branches that hang over your roof to let in more sunlight.
- Keep gutters clear so water drains away from the roof edge.
- Remove leaves and debris from roof valleys after storms.
- Ask about zinc or copper strips near the ridge, which can help slow algae growth.
- Schedule a house wash at the same time to keep the whole exterior looking fresh.
Is It Safe to Clean Your Roof Yourself?
We don’t recommend it. Walking on a wet, slippery roof is dangerous, and the wrong chemical mix or pressure can damage shingles, siding, and plants. A professional soft wash is safer, faster, and protects your investment.
Frequently Asked Questions
Does roof cleaning damage shingles?
Not when it’s done with the soft wash method. Low pressure and the right cleaning solution remove algae without stripping granules.
How long does a roof cleaning take?
Most single-family homes take a few hours, depending on the size and pitch of the roof.
Will the black streaks come back?
Algae spores are always in the air, so streaks can return over time. Soft washing kills the algae at the root, so it typically takes years, not months, for streaks to reappear.
Do you clean roofs in my city?
We serve McKinney, Plano, Frisco, Allen, Prosper, Richardson, Wylie, Celina, Fairview, and The Colony, and nearby communities across Collin County.
Ready for a cleaner roof? Foundation Pressure & Soft Wash provides roof soft washing in McKinney, Plano, Frisco, and across Collin County. Call or text (469) 659-7281, Monday through Saturday, 9am to 7pm, or request a free quote.
