Blog
Roof Cleaning by Material Type: What Works for Your Portland Roof
Not all roofs are the same — and the cleaning method that works great on asphalt shingles can damage a tile or slate roof. Here’s a material-by-material breakdown of what to use (and what to avoid) for safe roof cleaning in Portland.
Asphalt Shingles
The most common roof type in Portland. Asphalt shingles are durable but vulnerable to pressure washing, which strips protective granules and shortens roof life. Soft washing is the manufacturer-approved method for asphalt — low pressure plus a biodegradable cleaning solution.
Metal Roofs
Metal roofs resist moss better than asphalt, but algae and lichen can still accumulate. Use pH-neutral or non-corrosive cleaners. Avoid acidic solutions that accelerate oxidation. Soft washing works well here — low pressure prevents denting or coating damage.
Tile Roofs (Concrete and Clay)
Tile roofs are durable but brittle — cracking under foot traffic or high pressure. Clean with low-pressure soft washing and a solution designed for tile. Avoid walking directly on tiles when possible; use ridge boards or walkboards for access.
Cedar Shakes and Wood Shingles
Wood is the most sensitive material to clean. It absorbs moisture and can swell or split under pressure washing. Use a soft wash with a wood-safe, biodegradable solution. Avoid bleach concentrations that can dry out and crack cedar over time.
Slate Roofs
Slate is extremely fragile underfoot but very resistant to moss when properly maintained. Use a non-acidic cleaner and extremely low pressure. Slate chips and cracks easily — this is a roof type that almost always warrants professional cleaning rather than DIY.
Synthetic and Composite Roofing
Synthetic materials vary widely. Check manufacturer guidelines before cleaning. Generally, low-pressure washing with a mild solution is safe. Avoid anything abrasive that could affect the UV-stabilized surface coating.
Quick Reference Guide
| Roof Type | Recommended Method | Avoid |
|---|---|---|
| Asphalt shingles | Soft wash (low pressure) | Pressure washing |
| Metal | pH-neutral soft wash | Acidic cleaners |
| Tile (concrete/clay) | Low-pressure soft wash | Foot traffic, high pressure |
| Cedar/wood | Wood-safe biodegradable solution | High bleach concentration |
| Slate | Non-acidic, very low pressure | DIY — hire a professional |
| Synthetic | Mild solution, low pressure | Abrasive brushes |
Serving Portland and Surrounding Communities
Premium PowerWash has experience cleaning all major roof types in Portland and the surrounding metro area, including Lake Oswego, Beaverton, Tigard, Tualatin, Oregon City, Wilsonville, and Sherwood.
Not sure what type of roof you have? Call (503) 575-6575 or get a free estimate — we’ll assess it before we start.