State of the Green Roof Industry in the United States

Green roofs have entire roof tops covered with vegetation as opposed to shingles, bitumen, cement or gravel in conventional roofs. During the previous four years, the number of extensive green roofs (which are characterized by a relatively shallow depth of the growing medium) in the United States has grown at the rate of about 50% each year. Even then the total coverage area for green roofs in the US remains insignificant as compared with Germany, where green roofs have grown steadily over the past 25 years. The future of green roofs in the US depends not only on right incentives, which are more or less non-existent at this time, but also on the establishment of national performance standards, research facilities and test methods. The need for test standards and performance criteria is especially urgent for synthetic materials such as waterproofing membranes, root barrier layers, geocomposites and geotextiles, where many competing products can quickly flood the market, making it almost impossible to distinguish between what works and what does not. Given the right conditions, it is not unlikely that the size of green roof market in the US could far exceed that in Germany in eight years, and perhaps sooner.