Ballasted Roof System

What This Service Involves

A ballasted roof lays the membrane loose over insulation and holds it down with a layer of smooth river rock or concrete pavers rather than fasteners or adhesive across the field. This approach installs quickly, avoids penetrating the deck with thousands of fasteners, and the ballast helps shield the membrane from UV to extend its life. It suits structurally sound Northwest buildings that can carry the added weight and have the modest slope ballasted systems require. We verify the structure, detail the perimeters and penetrations carefully, and use the ballast to keep the membrane stable through our windy, wet winters.

Benefits

Loose-laid design installs quickly and economically; Ballast shields the membrane from UV for longer life; No field fasteners means fewer penetrations through the deck; Rock or pavers add fire resistance and wind stability; Pavers create walkable zones for rooftop equipment access

Our Process

1) Confirm the structure can support the ballast load; 2) Lay insulation and the loose membrane across the deck; 3) Secure and flash the perimeter, curbs, and all penetrations; 4) Distribute ballast evenly to the specified weight per square foot

What Affects the Cost

Structural capacity and any reinforcement required; Ballast type chosen, from river rock to concrete pavers; Roof size and how easily materials can be lifted up; Perimeter and penetration detailing complexity; Removal of the existing roof if a tear-off is needed

Best Time of Year

Dry summer weather keeps the deck clear for loose-laid installation and lets perimeter details bond before the rains.