Continuing Garden Roof Education

A.D. Willis Company attends RCI Green Roofing Seminar

Austin, TX - On November 19, 2010 The San Antonio/Austin Chapter of the Roofing Consultants Institute (RCI) hosted a Green Roofing Seminar at the Lady Bird Johnson Wildflower Center. Attendees, which included several members of the A.D. Willis Company staff, absorbed the latest information regarding green roofing in southern climates as well as updates on ongoing testing and new testing being conducted. “As a leader in the application of garden roofs, we want to stay abreast of the latest developments, because there are still a lot of unknowns, especially in this (southern) region,” says Charlie Glaze, A.D. Willis Company marketing manager.

Green roofs are not a new concept and have been popular in areas of the northwest, mid-west and northeast for some time. However, green roof production has been slow to gain momentum in the south. Noted green roof expert, Brian Gardiner of Austech Roof Consultants, presented some of the challenges surrounding green roofs in the warmer, drier climates.

- Supplemental water is necessary to sustain the plants, which puts an additional strain on a city’s water supply. - Growth medium needs to be deeper (6”) to help retain water, adding to the weight of the roof system. - The roof needs to drain to prevent putting hydrostatic pressure on the waterproofing membrane, while it still retains enough water to sustain the plants.

Other challenges cited that are not necessarily region specific include:

- The initial cost of a green roof compared to a traditional roof system. - Building code compliance regarding fire resistance, wind uplift, drainage and weight. - Insurance could be more expensive, if available at all. - The difficulty of leak detection and then the cost of repair

Following Mr. Gardiner’s presentation on the challenges of green roofs in a subtropical climate, attendees learned about the benefits from Mark Simmons, PhD. Dr. Simmons also cited water use as one of the main concerns, but he pointed out that while water use may be higher when getting the plants established, it will reduce significantly while simply maintaining them.

The threat of global warming has sparked the green building movement, and green roofs have been found to support the environment by:

- Reducing energy costs. - Reducing storm water run-off. - Reducing the heat island effect. - Extending the life of the roof’s waterproofing membrane, protecting it from extreme temperatures, hail, foot traffic, and direct sunlight. - Reducing noise pollution. - Improving the atmosphere by filtering pollutants, absorbing carbon dioxide, and emitting oxygen.

Following the presentations, the group of attendees visited the on-site green roof testing facility, where 24 experimental rooftops were constructed on metal insulated boxes to simulate green roof conditions. Past studies have helped determine which manufactures’ products performed well, and also which type of plants delivered best in terms of growth and storm water retention during simulated controlled rain events.