What is shingle roof cleaning?
Shingle roof cleaning removes algae streaks, moss, lichen and dirt from asphalt shingles without damaging them. Asphalt shingles are the most common roofing material on homes in the San Antonio area, and they are protected by a layer of small mineral granules. Those granules shield the shingle from sun, so cleaning has to leave them in place.
That rule shapes the entire method. Shingles are cleaned with Soft Wash, not with a pressure washer, and the way a crew treats the roof matters as much as the result. For the big picture, see safe roof washing on our homepage.
Cleaning is not the same as repair. A cleaning removes the growth and dirt on top of the roof, and it can help shingles last as long as they were built to. It cannot restore granules that are already gone, flatten curled edges or seal a leak. Treat it as maintenance for a healthy roof.
How are shingles cleaned?
The process uses a cleaning solution, a short wait and a low-pressure rinse. The solution is sprayed over the roof from the ground or a ladder, where possible, so crews can limit time on the surface.
- Pre-wet the surroundings. Plants, vents, windows and outdoor items are wet or covered.
- Apply the solution. It goes on at low pressure, evenly across the roof.
- Dwell. It sits long enough to break down the growth, and the crew keeps it from drying.
- Rinse. Clean water carries off the residue from the top of the roof downward.
The roof is rinsed with the flow of the water, never up under the shingle edges, so water does not get pushed beneath the shingles.
Shingle cleaning follows a few simple principles. Use the weakest effective method, keep the water moving in the direction of the shingles, and never spray upward under the tabs. Wind, temperature and sun are all taken into account, because a solution that dries too quickly does not work as well.
What are the signs your shingles need cleaning?
- Dark streaks that run down the roof, often on the shaded side.
- Moss in the shingle gaps and along the lower edges.
- Green or gray patches that may be lichen.
- Leaves and needles stuck in valleys and behind chimneys.
- A roof that looks dingy compared with the rest of the street.
- Dirty runoff stains on the siding or gutters.
- Shingles that look uneven in color from sun to shade.
- An HOA letter about roof appearance.
It also helps to check the details. Look at the lowest edge of the roof, where water collects, and at the area around vents and chimneys. These spots stay damp longest and often show the first signs of moss. If they look clean, the roof is probably in good shape.
What causes the buildup on shingles?
Asphalt shingles get a mix of pollution, pollen, dust and organic debris, and the humid San Antonio climate lets algae thrive on it. Algae can feed on limestone filler in many shingles, and that is why the streaks show up so readily on asphalt roofs.
Shade and trees make everything worse. A roof under mature oaks stays damp longer and collects more debris, so homes in Stone Oak and Shavano Park often see growth sooner. The streaking itself is explained further on the Algae & Black Streak Removal page.
Age matters, too. As shingles age, the surface roughens and loses granules, which gives growth more places to grip. A new, clean roof is much easier to keep clean than an older, neglected one.
The color of the roof plays a part. Lighter shingles show streaks less, while dark roofs show them clearly. Dark streaks absorb more heat than clean shingles, so a heavily streaked roof can run hotter in the Texas sun, and a cleaner roof may stay a little cooler.
What safe DIY checks should you do first?
You can learn a lot from the ground. Check the roof in daylight, with binoculars if you have them, and look at the gutters and downspout outlets for granules.
- Do not climb onto the roof. Algae and moss make shingles slick.
- Do not use a pressure washer, a broom or a scraper.
- Do not pour bleach on the roof from a bucket or sprayer, since the runoff harms plants and the mix is uncontrolled.
- Do photograph the roof each season and compare.
Gutters are worth a second look. Many shingle roofs drain into gutters that fill with debris, and clogged gutters push water back under the lower edge of the roof. Clean gutters make the roof last longer and keep dirty water from staining the fascia.
What happens during a professional shingle cleaning?
- The crew checks the shingle type, the condition and the access, and notes any damage.
- Plants and sensitive items are protected.
- The solution is applied at low pressure and left to work.
- The roof is rinsed from the top down, and gutters and downspouts are flushed.
- The crew rinses the landscaping and does a final check.
A trustworthy crew will tell you what they find. If shingles are curling, cracked or missing, they should suggest a roofer rather than clean over the problem.
A visit usually takes a few hours for an average roof, and heavier moss or a steep roof can add time. You will usually not need to be home, but you should move cars, furniture and potted plants away from the house first and keep pets inside until surfaces are dry.
What affects the price of shingle roof cleaning?
| Factor | Effect on the quote |
|---|---|
| Roof size | More square footage means more time and product. |
| Pitch and stories | Steep, tall roofs need more safety setup. |
| Amount of growth | Heavy moss takes more work than light streaks. |
| Extras | Gutter flushing, detached garages and added treatments can raise the total. |
Ask for the method in writing. If a quote says pressure washing for a shingle roof, ask more questions or look at other roof cleaning services.
Plan ahead for the next cleaning. A shingle roof in shade may need attention every few years, while a sunny roof can wait longer. Keep notes, take a photo each spring and fall, and book the cleaning when streaks start to spread, which is much easier than waiting for a thick coat of moss.
When is it urgent?
Book soon if moss is thick, shingle edges are lifting or the roof is losing granules, because growth holds moisture against the surface. Call a roofer first if you see leaks, daylight in the attic or missing shingles.
Think about the timing of any other work, too. If you are planning to replace the roof within a year or two, a full cleaning may not be worth it, but a roof you expect to keep for many more years benefits greatly. Cleaning before a sale or refinance can also help the home present well, and it gives an inspector a clearer view of the roof.
Finally, remember that every roof ages differently. Sun exposure, tree cover, roof pitch and the quality of the original installation all change how quickly dirt and growth appear. Use the signs above as a guide, and let the condition of your own roof tell you when it is time to clean.
Shingle roof FAQs
Will cleaning remove granules from my shingles?
Done correctly, it should not. Soft wash uses low pressure, so the granules stay in place. High pressure is what strips them, so avoid it.
Should I clean or replace my roof?
If the shingles are sound and the problem is streaking or moss, cleaning is usually the better step. If shingles are curling, cracked or missing, ask a roofer to inspect the roof first.
Does cleaning affect my shingle warranty?
Check the manufacturer's instructions. Many advise against pressure washing, and some describe approved cleaning methods, so keep your paperwork and ask before work begins.
Why are there granules in my gutters?
Some loss is normal as a roof ages, especially on a new roof. A heavy amount can mean the shingles are wearing out, and that is worth a roofer's inspection.
Do algae-resistant shingles still need cleaning?
They slow algae with copper granules, but they are not immune. Heavy shade, debris and humidity can still cause streaks over time.
How soon will the roof look better?
Light dirt may rinse away right away. Algae often keeps fading over the following days and weeks as rain rinses the treated roof.
Related services and areas
If part of your home has a tile roof, read about Tile Roof Cleaning. For detached buildings, see Commercial Roof Cleaning. We serve Stone Oak, Shavano Park and Helotes.