The Best Way to Clean Your Spray Polyurethane Foam Roof

Regular cleaning is part of proper spray foam roof maintenance. Here's how to do it correctly without damaging the system.

Why Cleaning Matters

Dirt, debris, biological growth (algae, mold), and organic material accumulate on the roof surface over time. Heavy dirt loading on topcoats can reduce solar reflectance — affecting energy efficiency. Biological growth can accelerate coating wear. And documented cleaning is typically required for warranty compliance.

The Standard Method: Power Washing

Low-pressure power washing is the most effective cleaning method for foam roofs. Use water pressure in the 1,000–1,500 PSI range. Higher pressures can damage the coating surface — avoid using industrial-grade equipment set to maximum pressure. Use a wide-angle spray tip (25–40°) and keep the nozzle at least 12 inches from the surface. Rinse with clean water after washing.

Cleaning Agents

For routine cleaning, plain water is often sufficient. For biological growth (algae, mildew), a diluted bleach solution (1 part bleach to 10 parts water) or commercial roof cleaner can be used. Always check with your coating manufacturer before applying any chemical cleaner — some products can affect silicone coating adhesion or appearance.

When to Clean

Clean during semi-annual inspections or when visually dirty. Clean before applying fresh topcoat during the recoat process — the inspection typically identifies cleaning needs. Avoid cleaning in direct sunlight on hot days — the cleaning solution can dry too quickly on hot surfaces.