Why Valley roofs need cleaning
Central Valley roofs collect field dust, pollen, leaf fall and, on the shaded north side and under overhanging trees, organic growth that holds moisture against the surface. On tile the buildup packs into the laps and valleys and slows drainage. On composition shingle it shows as dark streaking. Either way the roof is holding grit and moisture it was built to shed.
A dirty roof also hides problems. Cracked tiles, lifted flashing, loose mounting feet under the array and a downspout outlet packed solid all disappear under a layer of grime. Cleaning the roof puts eyes on all of it, and CA Solar Wash photographs anything that needs attention while the team is up there.
The roof product decides the cleaning method
Concrete and clay tiles are not interchangeable cleaning surfaces. Coatings, age, prior repairs and the manufacturer instructions matter. Eagle Roofing publishes specific limits for its concrete tile; that does not establish a universal setting for every roof. Confirm the product before agreeing any pressure-assisted method.
Asphalt shingle needs its own manufacturer-approved method. GAF advises against power washing shingles because it can dislodge protective granules. A low-pressure method still requires compatible products and a roof in suitable condition; cleaning cannot restore lost granules or repair a leak.
Working on a roof that carries solar
A solar array changes the sequence and the care required. This is what CA Solar Wash accounts for before starting.
- Identify the array perimeter, mounting feet, flashings and any conduit before the first drop of water.
- Keep high-pressure work away from module edges, junction boxes and cable entries. The panel glass is never pressure washed.
- Clear debris from between and beneath modules where it is reachable, rather than flushing it deeper.
- Wash the roof first and the panel glass afterward, so runoff does not re-soil clean modules.
- Check valleys and gutter runs afterward, because roof cleaning moves debris downhill into them.
- Note any lifted flashing, damaged tile or loose hardware found along the way and photograph it for you.
Method by roof type
Scroll sideways to see all columns.
| Roof | Method | What CA Solar Wash checks first |
|---|---|---|
| Concrete or clay tile | Product-compatible cleaning after the tile and finish are identified. | Tile age and condition, and whether the run can be walked safely. |
| Asphalt composition shingle | Low-pressure soft wash with dwell time and a rinse. | Granule loss, previous pressure damage and roof age. |
| Roof with a solar array | Roof cleaned first, array perimeter kept clear, panels washed separately with purified water. | Mounting feet, flashings, cable runs and any nesting under the panels. |
| Flat or commercial | Method decided on inspection. | Drainage, membrane condition and access. |
Runoff, planting and your neighbors
Everything washed off a roof goes somewhere. Before starting, CA Solar Wash looks at where the water will land: planting beds, a lawn, a pool surround, a driveway that drains to the street. Beds and delicate planting get covered or pre-wetted, and the work is sequenced so the runoff route is the one chosen, not the one discovered.
Wash water reaching a storm drain goes to a waterway, not a treatment plant, which is why the EPA treats outdoor washing as a stormwater issue. Keeping the chemistry to what the surface needs is part of that. So is not sending a plume across a shared driveway or a neighbor's car. If the layout makes containment difficult, you hear it before booking, not after.
Cleaning, stain treatment and roof repair are different jobs
Photograph dark streaks, moss, loose debris and the areas you want improved. Also disclose leaks, cracked tiles, fragile coatings and any roof or solar warranty. Appearance alone cannot establish why a stain is present or whether the roof needs repair.
The quote should identify the areas reached, cleaning products or method, runoff plan and limitations. Roof repairs, coatings, waterproofing and solar panel removal are not part of an ordinary roof clean unless a separate suitable scope has been agreed.
