You can tell an asphalt shingle roof cleaning was done right by four things: the stain is lighter without new bare patches, no fresh granules are piled in the gutters, the plants below are rinsed and unharmed, and you hold a written record of the product, pressure and method used. The Asphalt Roofing Manufacturers Association (ARMA) says high-pressure washing is likely to damage asphalt roofing and that cleaning is only temporary, so judge the job by the shingles it left intact, not by a perfectly even color the same afternoon.
Ventura County Roof Cleaning soft washes asphalt and composition shingle roofs across Ventura County. This page covers how to check the work, before, during and after. For how shingles are cleaned and what not to do, see asphalt shingle roof cleaning in Ventura County. For our local service, see soft wash roof cleaning.
Key Takeaways
- The goal is intact granules. A lighter roof with bare tabs is a failed clean.
- The scope should name the method. Product, pressure, dwell, rinse, plant protection and access belong in writing before work starts.
- Force is the red flag. ARMA warns against high-pressure washing; NRCA guidance also says not to scrub the shingle surface.
- Moss is not gone on day one. Treated moss weathers loose over the following weeks, so judge it after a rain, not during the visit.
- Keep the paper. Before and after photos plus the provider’s note of products and methods belong in your warranty file.
What a Shingle Clean Can and Cannot Do
A shingle roof cleaning is appearance maintenance: it lifts biological staining and loose growth, and it does not repair anything. ARMA’s algae discoloration bulletin says cleaning “is only temporary, and the discoloration may recur.” Set expectations by condition before you judge the result.
| Condition | What a good clean achieves | What it cannot do |
|---|---|---|
| Algae streaks | A clearly lighter surface, granules intact | Stop the streaks from returning in time |
| Moss | Growth treated and weakening, loose material cleared | Make every dead fragment vanish the same day |
| Lifted or curled edges | Nothing; the edges need a roofer’s look first | Flatten or reseal a shingle |
| Granule loss or bare patches | Nothing; that area should be left for inspection | Put granules back |
If you are not sure which of these you are looking at, our guide to black streaks versus shingle damage walks through the ground checks.
What the Written Scope Should Name
A good estimate tells you how the roof will be cleaned, not only that it will look clean. Every line below is something you can check on the day.
| Scope line | What a good answer looks like | Why it matters |
|---|---|---|
| Cleaning product | A named product the shingle maker allows | ARMA says mixing directions may vary among shingle manufacturers |
| Pressure | Soft wash, low pressure only (ours is under 500 PSI) | ARMA: “High-pressure washing systems are likely to damage asphalt roofing and should not be used” |
| Dwell | Left on for a set time, then rinsed | ARMA’s bulletin: “at least 15 minutes but no more than 20 minutes” |
| Rinse | A gentle water rinse the same day | ARMA calls for rinsing “by gently spraying the surface with water” |
| Plants and runoff | Pre-wetting, covering and rinsing landscaping | ARMA: apply the solution “carefully to avoid damage to other parts of the building and the surrounding landscape” |
| Access | Ladders or walkboards, with fall protection | ARMA says to “always work from a ladder and/or walkboards,” and recommends trained professionals do the work |
Our guide to choosing a roof cleaning company in Ventura County covers the rest of the vetting.
Red Flags on the Day
Most damage to a shingle roof during cleaning comes from force, not from the cleaner. NRCA’s Professional Roofing gave homeowners this rule in an April 2013 maintenance column: “Do not use a power washer or high concentrations of bleach, and do not scrub the shingle surface.”
Watch for these during the visit:
- A pressure wand pointed at the shingles. That is the single biggest risk to the granules.
- Brushes, brooms or scraping. Friction loosens granules, and scraping moss pulls them with the mat.
- Solution drying on the roof. Hot afternoon sun can dry it before the rinse; the dwell should end in a rinse, not a dry patch.
- Heavy foot traffic on mossy or brittle areas. Soft growth hides cracked tabs, and it is slick.
- Dry, uncovered plants below the eaves. Runoff reaches the landscaping first.
Check the Result: Same Day, First Rain, Weeks Later
One look on the day is not enough, because treated moss and staining keep changing after the crew leaves. Check three times.
| When | What to look for | What is a problem |
|---|---|---|
| Same day | Lighter streaks; tabs lying flat; gutters and downspouts flushed; plants rinsed | Fresh granules in the gutters or on the soil; bare patches; browned strips along the drip line |
| After the first rain | Moss browning and loosening; streaks still lighter | Lifted edges that were not noted before; water where it was not before |
| A few weeks later | Dead moss loose on the surface | Green regrowth only where the treatment never reached |
ARMA’s moss and algae page says roof debris “should be cleared regularly with a leaf blower or similar, non-abrasive method,” which is the right tool for dead moss that has weathered loose. A pressure washer is not. For the full die-off pattern after a moss treatment, see our roof moss and algae removal guide.
Keep a Record for the Warranty File
Shingle warranties differ by manufacturer, so the useful habit is a paper trail, not an assumption. Read your shingle maker’s cleaning guidance before the visit, then keep:
- Before photos of every slope, plus any lifted edge, bare patch or soft spot, taken before work starts.
- The written scope naming the product, pressure, dwell, rinse and plant protection.
- The provider’s note of what was actually used, with the date.
- After photos from the same angles, plus the gutters, so any granule loss is visible.
- The invoice, filed with your shingle warranty documents.
That record separates old damage from anything a clean might be blamed for, and it shows the roof was cleaned by low-pressure methods. How soon the streaks return depends on shade and exposure; our notes on how often to clean your roof cover that timing.
Frequently Asked Questions
How do I know if my shingle roof cleaning was done right?
The streaks are clearly lighter, the tabs lie flat, there are no new bare patches, no fresh granules are piled in the gutters, and the plants below are rinsed and unharmed. You should also have a written note of the product, pressure and method used. A perfectly even color on the same afternoon is not the test.
Should the moss be gone on the day of the cleaning?
No. A soft wash treatment weakens moss, and the dead growth browns and weathers loose over the following weeks, especially after rain. Loose dead moss can then be cleared with a leaf blower or similar non-abrasive method, which ARMA recommends for roof debris. Moss scraped off on the day often takes granules with it.
What should a shingle roof cleaning estimate include?
The named cleaning product, the pressure (a low-pressure soft wash), how long the solution stays on, how the roof is rinsed, how plants and runoff are handled, and how the crew reaches the roof. Each of those is something you can check on the day of the work.
What records should I keep after a roof cleaning?
Before and after photos from the same angles, the written scope, the provider’s note of the products and methods actually used, the date and the invoice. File them with your shingle warranty documents so old damage is easy to separate from anything that happens later.
What if I find granules in the gutters after a roof cleaning?
Photograph them and raise it with the provider right away. NRCA lists excessive surface granules in the gutters or downspouts among the problems a roof inspection finds, and ARMA warns that high-pressure washing damages asphalt roofing. A low-pressure soft wash should not leave fresh granules piled in the gutters.
Get a Shingle Clean You Can Check
Ventura County Roof Cleaning soft washes asphalt and composition shingle roofs across Ventura County at under 500 PSI, and we never pressure wash a roof. If a roof is near the end of its life, we say so on site rather than selling a clean. We do not publish a fixed price: every job is quoted after a free on-site look, and the estimate names the method. Request your free estimate.