Get vegetative roof installation right, to avoid costly repairs later

Proper installation is critical to green (vegetative) roofs because fixing problems later can be costly. “If the roof begins to leak, it means a costly disassembling of the vegetative layer, moisture retainers, and water flow base just to get to the roof membrane to check for faulty seams and other penetration points,” says Dan O’Donnell, president of the United Union of Roofers, Waterproofers & Allied Workers Local in St. Louis. O’Donnell says it is wise to test the roof membrane for leaks by plugging the drains and flooding the roof with water before adding soil and vegetation. http://www.stltoday.com/business/local/article_31fb5daa-521a-5222-9f3c-b... A crucial factor before installation is ensuring that the roof can support the weight of soil, plants, and the water that they retain. Vegetative roofs use engineered light-weight soil. The weight on the roof depends on the depth of the soil, the types of plants, and the volume of water it holds. When saturated with water, a green roof can add as much as 36 pounds per square foot to the roof’s overall weight, O’Donnell says. “The American Society for Testing and Materials has standards for dead loads on green roofs, which in some cases require a reinforced concrete deck,” he adds.