Cleaning methods should follow the finish manufacturer's care instructions. Abrasive treatment or unsuitable chemicals can affect the surface even when they remove visible dirt. Maintenance is easier when the exact finish is documented.
What to do next
Keep the product and warranty information available for the cleaning contractor. Ask for the proposed method before work begins and document existing staining. If the issue appears to be corrosion rather than dirt, obtain an assessment before treating it as routine cleaning.
Related Perkins guidance
Contact Perkins Roofing to discuss your roof and the appropriate next step.