Exactly what constitutes a "green roof?" According to the U.S. Environmental Protection Agency, green roofs are defined as roofs that are "planted over existing roof structures and consist of a waterproof, root-safe membrane that is covered by a drainage system, lightweight growing medium and plants."
Government entities and large corporations are the primary purchasers of green roof systems; however, there is a growing trend within the condominium, loft and apartment building high-rise market segments. These owners are converting less appealing, old roofs and patios into lush living spaces to attract tenants. According to one study, having a view of a green roof raises property values by as much as 9% and having access to it raises them by as much as 11%.
Here are some additional things to know about green roofs:
On a retrofit, it’s important to keep in mind that the existing structure was likely not designed with a green roof in mind. Stone ballasts, pavers, vegetation trays, trees and soil that become saturated after a rain all contribute to the load that the roof deck and building itself will have to endure. It’s important to have the building analyzed by a certified structural engineer prior to planning for any green roof project.
Another important factor is what happens if there’s a leak in the green roof. Unlike a conventional system where the roof is exposed, the waterproofing components of a green roof are often buried underneath layers of roofing material, stone features, soil and vegetation. You and your architect need to be cognizant of repair factors, such as specifying light-weight components that won't penetrate the roof system or interfere with drainage and can easily be removed if a problem does arise.
When selecting rooftop vegetation, remember one very important tip: The taller a plant grows up, the deeper the roots grow down. Using growing trays, planter boxes or plants with shallow root systems is recommended, as vegetation should not be in direct contact with the roof membrane.
Green roofs promote biodiversity and can provide an inviting habitat for birds, butterflies and insects. Plants often used for rooftop gardens include succulents, grasses, wildflowers and aromatic herbs, and even fruits and vegetables. It’s always best to consult with a landscape architect when designing and selecting the right features.
Be sure to check with the U.S. General Services Agency, U.S. Green Building Council and the Environmental Protection Agency for current federal green roof legislation, policies and tax incentives. State and local governments may also offer similar incentives. A list of available programs by state is available at www.myplantconnection.com/green-roofs-legislation.php.
Green roofs are gaining in popularity and offer many benefits. When considering one for your building, remember to always do your homework, check for government incentives, and most importantly, use a commercial roofing company with experience installing green roofs so you don't waste your "green" while going green. Bade Roofing Company is highly experienced in green roof installation. Check out our project at 700 Market Street here:
Bade Roofing Company. Founded in 1954, Bade Roofing Company, Inc. is one of St. Louis, Missouri's premier family-owned and operated commercial and industrial roofing specialists. Bade Roofing installs roofing systems on major retail centers, grocery stores, hospitals, schools, warehouses and office buildings. www.baderoofing.com