Why Cleanliness Affects Performance
Cool roof coatings work by reflecting solar radiation rather than absorbing it. A layer of dust, dirt, or biological growth reduces that reflectivity, meaning a dirty cool roof gradually loses some of its cooling benefit even though the coating material itself is unchanged.
The Right Cleaning Method Matters
High-pressure washing can strip or damage the elastomeric coating that gives cool roofs their reflective properties. Soft washing with appropriate low-pressure application and biodegradable cleaning agents removes dust and biological growth without compromising the coating's integrity or reflectivity.
Recommended Schedule
Most Arizona cool roofs benefit from a cleaning every 2–3 years, similar to standard tile or shingle roofs, though homes in particularly dusty areas or with visible staining may benefit from more frequent attention to preserve reflective performance.