River Rock Roof Ballast

Additional benefits of ballast on a flat roof.

River rock roof ballast.

For purposes of this section ballast shall mean river rock aggregate or larger pavers or other means of weighing down a roofing membrane over a substrate to resist wind uplift john geary vice president of marketing firestone building products says there s a growing perception in the building community that reflective roofing is the panacea for energy efficiency. Ballast stone can crush the underlying insulation creating weak spots in the roof membrane. Once completed the epdm membrane is held in place using one of the following materials as ballast with a minimum weight of 50 kg m. Concrete pavers with smooth trowel finish min.

Over time the stones move around creating bald spots where the system isn t held down at all. 1 1 2 river rock is primarily used in landscaping applications. Our roofing ballast is produced to meet astm standards often required by architects engineers and insurance companies. Ballasted flat roofs are a popular choice especially for commercial buildings.

A ballasted roofing system normally consists of river rock ballast over a membrane rigid insulation and a metal roof deck. In windy areas ballast stone can actually blow off the roof creating projectiles below. Gravel in form of round smooth river washed aggregate without broken pieces nominal 16 to 32 mm. Crushed gravel that must be graduated.

Stone ballast is no longer allowed by many building codes. Though the solar reflectance is lower than a traditional cool roof the river rock has high thermal emittance properties and the mass of the ballast acts as a heat sink resulting in according to some a similar overall performance to a cool roof. The gravel in a ballasted roof helps absorb heat preventing the sun from heating the roof materials below and making the roof more energy efficient.