Roof cleaning services

Soft washing is the core service. The Asphalt Roofing Manufacturers Association describes the effective approach as applying a cleaning solution — ARMA cites a 50:50 mix of laundry-strength liquid chlorine bleach and water — leaving it to dwell for 15 to 20 minutes, then rinsing thoroughly with low-pressure water. The chemistry does the work; the water only rinses.

Moss removal is a separate job. Algae is a stain; moss is a plant with a root structure that holds water against the shingle and lifts its edges. Heavy moss usually needs a treatment plus careful physical removal — and ARMA warns against scrubbing, because friction loosens granules. Expect this to be a slower, dearer visit than a straight algae wash.

Preventive work means zinc or copper strips near the ridge, which release metal ions in rainwater that inhibit regrowth. Manufacturer guidance from Malarkey notes these are ideally installed during a new roof rather than retrofitted, so ask honestly whether a retrofit is worth it on your roof.

One thing to understand about all of it: the effect is temporary. ARMA is explicit that cleaning results are only temporary and discoloration is likely to recur. A company promising permanent results is overselling. Algae-resistant shingles, which use copper granules, are the durable answer — and that is a re-roof decision, not a cleaning one.

How to choose

Insist on soft washing for asphalt shingles

ARMA states plainly: never use a pressure washer on an asphalt shingle roof, as it causes granule loss and very likely premature failure of the roof system.

Ask how they protect landscaping

Chlorine solution kills plants. ARMA advises taking proper precautions to protect landscaping and surrounding areas. Pre-wetting, tarping, and post-rinsing should be in the scope.

Get moss quoted separately from algae

They are different amounts of work. Bundling them into one number makes it impossible to tell whether the moss is genuinely being dealt with.

Ask about gutters in the same visit

Debris washed off the roof ends up in the gutters. If gutter clearing is not included, you may need it immediately afterward anyway.

Confirm insurance and fall protection

Roof work is genuinely dangerous. Ask for a certificate of liability and workers' compensation insurance from the insurer, not a photocopy from the contractor.