Roof cleaning and moss removal: know what you are paying for.

Is it moss, staining or a roof problem underneath?

Ask for photographs and an explanation of the proposed treatment. Is the concern moss, surface staining, blocked drainage or damaged roofing underneath? A label such as “dirty roof” does not establish which problem needs fixing. If a replacement is recommended, request the condition findings that support it.

Ask how the roofer will remove moss and clean the roof.

For asphalt shingles, GAF warns that pressure washing can damage the shingles. Have the provider explain its process and the manufacturer guidance it follows for your actual covering. Do not assume that “soft wash” tells you everything about the chemicals, application or physical removal involved.

Check how runoff, plants and solar panels are protected.

Ask how the contractor will manage runoff, protect plants and keep cleaning materials away from sensitive equipment. Identify skylights, gutters, solar panels and any rainwater collection system before work is priced. These are scope questions for the provider, not instructions to mix chemicals or undertake roof work yourself.

Know when the treatment should produce results.

Will the visit remove debris, apply a treatment, include a later return or some combination? Ask what the roof should look like immediately afterward and when the provider expects the agreed result. Put any return visit and its price in the proposal. Avoid paying for an undefined promise that the roof will eventually look different.

Keep roof repairs separate from the cleaning quote.

If shingles, flashing or other components need repair, request photographs and a separate description of that work. Ask what happens if damage is exposed during cleaning and who must approve additional charges. A moss-treatment invoice should not silently become authorization for a larger roofing project.

Read the moss retreatment promise and exclusions.

Ask which property conditions may contribute to recurring growth and what upkeep the roofer recommends. Check any retreatment promise, its duration and exclusions. Keep the treatment record with your roof documents. Neither a tidy appearance nor a recurring cleaning plan guarantees that the roof is watertight.

Questions before you decide.

Make the next decision easier.