Green Roof FAQ
What is a Green Roof?
A Green Roof is a contained green space on top of a structure that is above, at, or below grade. All Green Roofs contain a structural deck, waterproofing membrane, root barrier material, drainage layer, filter cloth, growing medium and plants.
Why Have a Green Roof?
- They are beautiful!
- Increases marketability and selling "Green"
- Insulates the roof, saving on energy costs for heating and cooling
- Lengthens roof life, double to triple the life of a standard roof
- Reduces storm water runoff and improves quality of runoff
- Removes air pollution
- Increases biodiversity
- Reduces the urban heat island effect
What kind of plants do well on Green Roofs?
Plant selection will depend on the microclimate of the project. Plants should be able to tolerate tough growing conditions such as seasonal drought, high temperatures, and reduced area for roots.
Does a Green Roof need maintenance?
Yes! During the dry months of summer, Green Roofs need to be watered once every 1-3 weeks (depending on the type of Green Roof and plant selection). During the establishment period, check for weeds once every few weeks until the plants have covered the soil. Then check for weeds a couple times per year. Only fertilize plants when they are nutrient deficient. Most plants and growing medium contain fertilizer when they are sold.
What kind of growing medium should I use?
Green Roof growing medium is an engineered combination of organic and inorganic matter. Most are designed to have a high percentage of coarse and fine inorganic lightweight aggregate. Examples of inorganic material are sand, expanded clay, expanded shale, expanded slate, perlite, rock wool, pumice, vermiculite, and volcanic rock. Examples of organic material are compost, peat, sawdust, and worm castings.
What is LEED?
The Leadership in Energy and Environmental Design (LEED) Green Building Rating System encourages and accelerates global adoption of sustainable green building and development practices through the creation and implementation of universally understood and accepted tools and performance criteria.
What's the difference between an Extensive Green Roof and an Intensive Green Roof?
An extensive Green Roof has 6" or less of growing medium. They are usually planted with low maintenance groundcovers and are inaccessible. Their primary function is ecological and economical.
An intensive Green Roof has more than 6" of growing medium. They use a diversity of plants allowing for a greater range of design and are usually accessible. Their function may be ecological, economical and / or social.
Can people walk on the Green Roof?
Many of our groundcovers can tolerate a low amount of foot traffic. Generally, Green Roofs are not designed for foot traffic, but occasional traffic for maintenance will not harm the plants.