Green Roofs use of Expanded Clay and Lightweight Expanded Clay Aggregate

The State of Florida has recently requested studies analyzing the use of gravel and aggregate on roofs and the potential of gravel ballast to break windows and other fenestration components of a building during hurricanes.

Preliminary research by the University of Florida shows that gravel ballast may be the cause of unnecessary glass failure and subsequent water damage.

Hurricane Alicia in 1983 devastated the Houston area, and much of the urban fenestration damage was attributed to gravel ballast ripped off the roofs by the hurricane force winds and shot across the city like pellets.

As Florida's green roofing industry develops, designers should be aware of the potential for tort damage liability once their specified product damages anothers property.

We should be careful about placing any gravel or pellet like material in a green roof until all the appropriate studies have been conducted to determine the level of safety for such product use.