FREQUENTLY ASKED QUESTIONS
FAQ Green Roofs provides quick answers
In fact, this depends on the Geen Roof Type. However, here is a range for all the materials above the waterproofing (roofing): Extensive Green Roof with 5" depth costs vary from $15/sf and an Intensive Roff Garden with shrubs and trees starts at $50/sf . Obviously the larger the area and the easier the project is accessible for construction it the cost go down. Because all roofs are different it is hard to have a price list for an installed Green Roof. Actually, in 1993 Green Roof Technology experienced a project where material had to be flown-in by a helicopter - at $2,100/hour. Also, construction management plays a crucial role in price finding as well whether you buy a Green Roof from a roofing company or directly from the source. Certainly this is one of our biggest strength - helping to keep costs down. The more information about a new project the more accurate cost estimations. FAQ Green Roofs #1
Yes, of course. In fact, many of our Green Roof projects involve existing buildings. However, every Green Roof Type has a weight. Additionally, the weight of retained water (we cannot change the weight of water) that is a crucial for the plants to survive and for stormwater retention. Since nobody wants a collapsing roof the structural integrity is the number one item to determine. A structural engineer is required, we can make recommendations. Step 2: Evaluating existing roofing/waterproofing is part of our standard operational procedure on all projects. As a rule of thumb, we recommend to replace existing roofing if it is older than 10 years. Certainly it is the best time consider a leak detection system. See also Services. FAQ Green Roofs #2
Modular or tray systems are nothing else than pre-planted boxes/containers made from metal or plastic. Although these come with internal drainage system, they are not reliable. In facts, The only function of the box is for easy shipping and quick installation by unskilled labor. Since the boxes are filled and grown (far)away from the project the costs are according high. Tray suppliers say, that the advantage is that you can move these later - not sure why. Certainly the disadvantages are that the maintenance is higher, the cost are higher, no flexibility, less diversity and high potential of damaging the roofing during installation. Instant green á la "mow-blow-go" style is questionable in regards of sustainability.
Monolithic Green Roof system or layered systems go from wall to wall, all fully integrated, seamlessly protect the roof, and highly flexible in meeting ALL design intents at the lowest price. Such loose-laid, wall to wall, or continuous systems, assembled on the roof guarantee functional drainage, water retention, plant diversity, roof protection, and potential combination with solar. The way to go. FAQ Green Roofs #3
Yes, absolutely. In fact it is possible from 0°-90° (vertical)! Keep in mind the costs for material and installation will super-proportional increase the steeper the slope. Everything over 5-8° requires more attention to detail and understanding of water flow and distribution. Certainly experience is required to prevention of erosion. Green Roof Technology cannot influence physics/gravity. However, we learned how to use gravity for engineering and without visual disturbance and over engineering. Climate Change with an increase of drought and heavier rail fall are also part of our considerations - unlike others. FAQ Green Roofs #4
This really depends on the Green Roof type, certainly on the climate zone, and future Climate Change. Over the last 40 years Green Roof Technology has designed Green Roofs that have been maintained only every other year or only once in five years. We understand that every natural area (on grade or ground disconnected) undergoes a change based on the environment and by natural succession.
If natural succession is not wanted maintenance is always high - means monthly or even weekly. It is like keeping a manicured lawn in shape that requires regular mowing - sometimes even twice a week. In general our Green Roof solution are always engineered to keep maintenance as low as possible and within the design intent and for more natural appearance. Based on visual indications (indicator plants), simple physical tests, and education all of our Green Roofs exceed customer expectations over decades. Our experience is your advantage. FAQ Green Roofs #8
Water is the key of life and we should protect our water sources. Irrigating a new installed Green Roofs is always a good start. Do I need an irrigation system for that? No.
In general this always depends in what climate zone your are and when you build a Green Roof in the dessert with lush vegetation that is not present in the surrounding environment - an irrigation system is necessary. Whether that is environmentally friendly - No (why draining the Colorado river for a Green Roof in LA when farmers have water restrictions?). We have engineered Green Roofs in any climate zone under considerations of local water resources - it might not look always super lush and green but it is as natural and environmentally friendly as it can get. We even designed systems that are only depending on the grey water from the building underneath which creates a natural water cycle where we share our precious resources with nature.
Short: Irrigation systems on a green roof reduce stormwater retention and stromwater detention - the main reason why we build them in the first place. If designers or professionals emphasize on irrigation systems at project then we question the sustainability (and the high costs for installation, maintenance and operations of such systems. FAQ Green Roofs #9
A Green Roof shall last as long as the structure and should be fully reused when the structure is going to be removed!
When other say: you roof should last 2-3 times longer it just shows some deficit in experience. We know when a roof/roofing is properly installed, with attention to detail, the Green Roof components have proven a lifespan of a lifetime (centuries), and if the maintenance goes beyond "weeding" it will last as long as the building and no day less. With climate change in mind, we go even further because our solution will adjust and they are flexible when the owner's design intent will change. It is an investment that never loses value. FAQ Green Roofs #10