The Purpose of Roofing Granules on a Flat Roof

Granules serve several important functions on commercial flat roofs. Here's where they're used and why they matter.

UV Protection on Modified Bitumen

Granulated modified bitumen roofing uses embedded mineral granules as the primary UV protection layer for the bitumen membrane beneath. Without granules, the bitumen would degrade rapidly from sun exposure. The granules also provide some impact resistance and improve the aesthetic appearance of the surface.

Foot Traffic Protection on Coating Systems

On silicone and acrylic coating systems, broadcast granules are applied into the wet coating at designated foot traffic areas — around HVAC units, near roof hatches, and along service paths. The granules become embedded in the cured coating, creating a textured surface that improves traction and reduces abrasion from foot traffic. This protects the coating from wear in high-traffic zones while allowing the smooth, reflective coating to remain in low-traffic areas.

Walkway Pads

Pre-fabricated granule-surfaced walkway pads are another option for high foot traffic areas. These pads are installed over the existing roofing system and provide a designated path for maintenance personnel.

Granules on Spray Foam Roofs

For spray foam roofs in high foot traffic areas, granules are broadcast into the topcoat while it's still wet — creating a textured, slip-resistant surface. This is typically done around HVAC units and rooftop access points where regular maintenance foot traffic occurs.