LIVING ROOF FAQs

Q. How does a living roof compare in cost to other roofing?

A. It costs more. A living roof is a vegetated cover applied over the waterproofing. It doesn't replace the cost of the waterproofing; it is a cost in addition to the waterproofing. [back to top]

Q. Are there tax incentives or grants available for green roofs?

A. At present, there are relatively few national incentives. However, incentives may be provided by specific municipalities and/or local environmental groups. For example, living roofs facilitate greater capacity to “manage” storm water on-site. In some cases, this has allowed the property owner to reduce offset fees, downsize retention ponds, increase FAR, and in some cases qualify for additional density rights. Contact your local or county government to see if any incentives are available in your area. [back to top]

Q. Why spend the money for this additional component on the roof?

A. The living roof provides tangible benefits. It extends the life of the underlying roofing by 2 to 5 times, it reduces storm water discharges, it cools the surface of the roof. These features have quantifiable economic benefit. [back to top]

Q. Can a living roof save money?

A. In many cases yes, especially if considered during the civil engineering of the site. Reductions in other storm water management infrastructure or offset fees sometimes exceed the cost of the living roof. [back to top]

Q. How many LEED™ credits will a living roof receive?

A. Living roofs can earn as many as 15 credits under the LEED TM (Leadership in Energy & Environmental Design) system, depending on design and level of integration with other building systems. In some instances, living roofs may not contribute directly to achieving points under the system, but they can earn points when considered as other sustainable building elements such as reduced site disturbance, protected or restored open space, andscape design that reduces urban heat islands and roof space, and/or 3) storm water management. [back to top]

Q. How much does a living roof weigh?

A. The typical extensive living roof weighs approximately 7 psf for each inch of thickness when fully saturated. Thus, a 4” system weighs about 28 psf when it is completely soaked. Confirming capacity of the structure to support a living roof is an important first step. [back to top]

Q. Do living roofs work in retrofits of existing buildings?

A. Yes, but you are starting with greater limitations. First, the capacity of the existing structure to carry the additional load should be confirmed. Second, the quality of the existing waterproofing needs to be assessed before placing the new overburden on top. We can suggest ways to perform that testing. [back to top]

Q. Do you warranty them?

A. In some cases, this can be single source warranty covering waterproofing and the living roof system, providing one point of recourse to the building owner. Yes, we warrant two aspects of the vegetated cover. First, we warrant the removal and replacement of the overburden should access to the underlying waterproofing be needed – typically to repair a leak. This warranty requires some means of locating the leak prior to removal of material. Second, we warrant the ongoing success of the plantings. This warranty requires an ongoing maintenance program to identify and address issues before they become major problems. [back to top]

Q. Will living roof plants survive in our region?

A. Almost definitely. We work very close with our staff horticulturist to specify plants that are suited to your specific climate. The most common plant material is a flowering succulent that will perform through all seasons with little maintenance. [back to top]

Q. How long will the Green Roof last?

A. Your green roof will double or triple the life expectancy of your existing roof by protecting it from human activity and wind-blown debris; shielding it from UV radiation; and buffering it from temperature extremes. Since the green roof is a living plant, it will last indefinitely. The water retention mat and root stabilizer and drainage carrier life expectancy is over 70 years! [back to top]

Q. What maintenance is necessary?

A. Maintenance is important for all roofs and especially important for living roofs. Immediately after installation, frequent maintenance visits will help ensure proper root establishment and plant coverage. In the first year of grow-in, we recommend monthly visits. Thereafter, maintenance can be tapered down to once per season if all is going well. We focus on achieving fast coverage in order to minimize ongoing maintenance needs. [back to top]

Q. What kinds of issues are addressed in your maintenance service?

A. Assessment of roof drainage, health of the plants, adjustment of growth media nutrient and ph levels, pest and infestation control, general pruning and weeding, temporary irrigation, and general assessment of conditions influencing plant performance. [back to top]

Q. What if I have to fix a leak in my roof?

A. Leaks can readily be located and fixed. New electronic technology, such as electric field vector mapping (EFVM), which can rapidly and accurately pinpoint even minute holes. This system is more reliable than the older flood testing method; need not be installed in advance, and can even be used on steeply-sloped surfaces. Repairs to the waterproofing are typically quick, and disturbance of the green roof is minimal. It is important to note that, leaks in living roofs are less common than conventional roofs because of the physical and UV protection of the plants and soil media. [back to top]

Q. Can living roofs be installed on sloped roofs?

A. Yes, we can install living roofs on slopes up to 45 degrees. There are a variety of slope retention systems. We can recommend the right system for your specific situation. [back to top]

Q. What kind of roofs are not suitable for living roofs?

A. Living roofs can be installed on virtually any roof, but practicality should be exercised. If the roof area cannot be accessed for future service, it might not be a good candidate. Likewise, the area should be conducive for plant growth. If large mechanical equipment creates extreme air flows, plants may not grow in that vicinity. [back to top]