The Guide: Vegetative Roofing Systems

One sustainable storm water management technique which continues to grow in popularity in Florida is the application of green roof technologies. This involves replacing or supplementing a traditional roofing material with vegetation. The vegetation prevents the rain from quickly running down the roof surface and offsite. Water instead percolates through soil and feeds plants in the process. The vegetative roof system provides a storage component and enhances the quality of runoff through natural filtration. In general, the system is composed of a waterproofing layer, a soil layer, and a plant layer. A vegetated roof is obviously easiest to create on a minimal slope, but it can be created on surfaces with a pitch of up to 45° with large trees, shrubs, and other landscapes. Vegetative roofs require irrigation and drainage systems to maintain the garden, which can add considerable load to the roof.

In contrast to the intensive design, extensive roof systems are primarily built for the environmental benefit. They typically use only inches of soil depth and contain small, hardy plants and thick grasses which are accessed for maintenance. Additionally, loads to a building are between 15-50 lbs per square foot. The blocks are usually a heavy gauge container with about 4” of soil supporting a low-growing plant species. A pad is fastened to the bottom of the block to protect the roof surface and allow controlled drainage through the unit. The typical weight of the system is 12-18 lbs per square foot. The cost of a green roof system can vary considerably depending upon the type of installation and factors such as the overall size, plant selection, depth of growing medium, use of irrigation, and accessibility options. It is important to note that, while green roof technology does typically require a greater initial investment, the system can significantly extend the life of the roof and reduce the heating and cooling costs of a building.

As with many sustainable management practices, one must look at a life-cycle analysis to truly compare the costs. Thousands of property managers and construction professionals are instituting Vegetative ‘Green Roofs’ on their facilities across all of Florida.

RAMCON maintains a complete line of vegetative roofing solutions, as well was photovoltaic (solar) and highly reflective systems for lifetime roof savings. Learn more about vegetative roofing systems online at www.vegetativeroofing.com