Do not use high-pressure washing as a default cleaning method for asphalt shingles. Choose a cleaning approach approved by the shingle manufacturer.
Do not use high-pressure washing as a default cleaning method for asphalt shingles. Choose a cleaning approach approved by the shingle manufacturer.
A cleaner appearance is not proof of a sound method
GAF's moss guidance specifically cautions against pressure washers and unsuitable treatments because they can damage or stain the roof. A contractor's impressive before-and-after video does not establish compatibility with your shingles.
Ask what pressure, equipment, and treatment are proposed and how the method follows your product's guidance. The phrase soft wash is not a complete specification either. The provider should explain what is being applied and how plants, runoff, and surrounding surfaces will be protected.
Identify what needs cleaning
Algae streaks, raised moss, ordinary debris, and deteriorated shingles are different conditions. Ask for an assessment before committing to treatment. A roof with damaged material may need repair rather than a cosmetic cleaning.
For example, if one provider recommends cleaning and another recommends replacement, ask the second to show the actual damaged covering. Ask the first whether that damage affects the proposed cleaning method. The disagreement should be resolved with evidence.
Do not climb the roof to experiment with a small section. Request a roof assessment and retain the approved cleaning method and photographs with the home records.
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Editorial team
Our editorial team publishes homeowner guides with sources linked in the article. For a recommendation about your roof, request an inspection of the property.
