Green Roof F.A.Q.

What do I need to know about my building before I initiate a green roof installation?

You will need to know the slope, the structural loading capacity, and existing materials of the roof, as well as the nature of any drainage systems, waterproofing, and electrical and water supply in place. You should also consider who would have access to it, who will do maintenance, and what kind of sun and wind exposure the roof gets.

For a deeper insight into green roofs and green roof design, attend one of our Green Roof Professional Training Courses, or purchase one of our course textbooks from the Green Infrastructure Store.

What kinds of landscape design should I use and what plants can I grow on my roof?

Plant selection depends on a variety of factors, including climate, composition and depth of growing medium, loading capacity, height and slope of the roof, maintenance expectations, and the presence or absence of an irrigation system. A Green Roof Professional (GRP) would be able to advise you on suitable plants and design of the plantings. Contact a GRP via our GRP Directory.

How much does a green roof cost?

The cost of a green roof varies considerably depending on the type and factors such as the depth of growing medium, selected plants, size of installation, use of irrigation, and whether they are to be accessible on inaccessible - intensive, semi-extensive or extensive. Intensive green roofs typically require greater investment but confer the benefits of accessibility. An installed extensive green roof with root repellant/waterproof membranes may be installed for $10-$24 US per square foot. While green roofs typically require a greater initial investment, it is important to keep in mind that they can extend the life of the roof membrane and reduce the heating and cooling costs of your building. Speak to a qualified Green Roof Professional about the range of costs and benefits for different green roof systems and designs.

How can I purchase a green roof system for my home or building?

You should consult a Green Roof Professional or contact a green roof manufacturer directly and speak to a sales representative. Contact information for GRHC members and GRPs can be found in our Member Directories.

hamiltonbldg mec greentech
Green roof at Hamilton
Building in Portland, OR
Green roof at Mountain
Equipment Co-op in Toronto, ON
Modular green roof system
with low lying shrubs

Who can design and install green roofs and walls?

A Green Roof Professional (GRP) should be the professional of choice on any green roof project, and many of our GRPs are also equipped to design and install green walls. Some jurisdictions specify that a GRP be part of any green roof design team.

Because green roof systems include materials not found on conventional roofs, we recommend that you choose a qualified roofing contractor with experience in green roof installation to install the non-living components (e.g., vapour barrier, waterproof membrane). Contractors can be found in our Corporate Members section.

You can also contact a roofing consultant, who will assess your roofing design needs, ensure quality control and recommend a suitable green roof system.

Landscape architects, landscape contractors, and system manufacturers frequently design green walls.

How many LEEDtm credits can I recieve?

Green roofs can facilitate a significant improvement in the LEEDtm rating of a building, contributing as many as 15 credits under the system, depending on design and level of integration with other building systems. In some instances, while green roofs may not contribute directly to achieving points under the system, they contribute to earning LEEDtm credits when used with other sustainable building elements. For example, green roofs can earn direct credits under the following:

  • Reduced Site Disturbance, Protect or Restore Open Space
  • Landscape Design That Reduces Urban Heat Islands, Roof
  • Storm Water Management
  • Water Efficient Landscaping
  • Innovative Wastewater Technologies
  • Innovation in Design
(the above is an excerpt from "Green Roofs and Maximizing Credits Under the LEEDTM Green Building System", by Richard Kula in The Green Roof Infrastructure Monitor, Spring 2005.)

Where can I learn more about green roofs?

Our Education Program is the source for the most comprehensive information on green roofs and walls in North America.

For general information on green roofs and walls, please check out the rest of our web site and the Living Architecture Monitor magazine. More information can also be found on some of our Members' web sites.

What sort of research is being done on green roofs?

A considerable amount of research on the public and private benefits of green roof infrastructure in different climate zones, different built environments, and at different scales needs to be conducted in order to forge a new industry through the development of supportive public policy.

One of Green Roofs for Healthy Cities' goals is to encourage that research through our Committees.

What sort of policy and funding support is available for green roofs and walls?

Green Roofs for Healthy Cities is working with local partners in a number of cities to develop cost effective direct and indirect financial support for green roof and wall implementation that meets local/regional needs.

One of the ways that we try to encourage the development of local markets for green roofs and walls is by running Green Roof Symposia in various cities. For more information on this initiative, please contact This email address is being protected from spambots. You need JavaScript enabled to view it. .

A list of available incentives and fundings sources is available to our members in the Living Architecture Toolbox.  For more information on GRHC membership, click here.

Green Infrastructure Design Charrette

About Green Roofs

by Steven Peck
GRHC founder/president

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