Start with the roof, not the equipment.
Share the roof material, approximate age if known, visible issues and any available manufacturer information. If you do not know the product, say so. Ask the provider to identify it before deciding on a cleaning process.
A cleaner should explain why the method fits the material and condition. The proposal should identify products, application and removal steps, precautions, and anything that requires a roofer’s assessment first.
Asphalt / composite shingles
High-pressure rinsing can remove protective granules. GAF warns against this approach. Ask for a manufacturer-compatible process, treatment of existing damage and a plan that avoids aggressive scraping. GAF roof-care guidance
Ask: “Which instructions for my shingle product does your method follow?”
Cedar shakes or shingles
Ask for demonstrated experience with wood roofing and the relevant product’s maintenance guidance. Do not assume the process used on asphalt is appropriate for cedar, or that a preservative or coating is included or needed.
Ask: “How will you assess the wood’s condition and avoid damaging it during cleaning?”
Metal roofing
Identify the finish or coating and request its care instructions. Ask how the crew will protect seams, fasteners and adjacent materials, and avoid cleaning products or abrasion that are incompatible with the finish.
Ask: “What does the coating manufacturer allow, and how will you protect it?”
Concrete or clay tile
Ask for the specific tile manufacturer’s cleaning guidance and a safe access plan. The crew should explain how it will avoid damaging tiles and what happens if it discovers cracked or displaced pieces.
Ask: “Who evaluates existing damage, and how will you access the roof without making it worse?”
Break “roof cleaning” into line items.
- Roof debris: the sections being cleaned and how material will be removed.
- Stain or growth treatment: what is being treated, with what, and expected limitations.
- Moss: physical removal, treatment, follow-up, or a combination.
- Gutters and downspouts: clearing, checking flow and handling any blockages.
- Property protection: access, landscape precautions, overspray and runoff control.
- Cleanup: debris disposal and the condition of paths, decks and planted areas afterward.
Know when cleaning is the wrong next step.
If there are leaks, loose or broken materials, extensive deterioration or uncertainty about the roof’s condition, ask for an assessment from a qualified roofer. Cleaning does not repair a roof, and an attractive after-photo does not prove that water intrusion or underlying damage has been resolved.
Material, condition, nozzle, distance and technique all matter. This guide does not provide DIY pressure settings or chemical mixtures. Ask the professional to show the applicable product guidance.
Sources & further reading
Source review: November 11, 2026. Check current requirements for your property and the product on your roof.