june 2003

 

Promoting Residential Greenroofs in Seattle and the Pacific Northwest
By Patrick Carey

The Northwest EcoBuilding Guild is the Pacific Northwest’s leading ecological building association whose members include builders, designers, homeowners, trades people, manufacturers, suppliers and others interested in sustainable building.  Founded in 1993 by a small group of people who were already incorporating green building ideas into their practices, they formed the Guild for the purpose of networking and exchanging areas of expertise.  Since then, the Guild has grown to seven chapters around the northwest.  A vital organization, its mission is to function as an educational forum to facilitate building practices that protect human health; encourage sustainable resource usage; and foster long-term economic vitality.

The Northwest EcoBuilding Guild’s Central Puget Sound Chapter is proud of the efforts and successes of the Green Roof Project.  Three years old this coming August, the focus of the Green Roof Project is to examine feasibility and develop a cost-effective and reproducible model of the eco-roof building technology appropriate for wide-scale residential application in the Northwest. We have collected $12,500 from various sources such as grants and donations, convinced various green roof component makers to donate about $29,000 worth of assembly parts, called for volunteers to do everything from haul dirt to do various research activities, got various roof owners to let us use their roofs as experiments – all without warranty agreements, and set about the process of installing green roofs for the residential market that were experimental assemblies.

Planted green roof of April 3, 2003;  Planting the cut sedums on the roof; Photos Courtesy Patrick Carey

We analyzed the existing green roof assemblies, set up email, phone, and in person correspondence with those who knew more than we did, read the literature, did web searches, and then charged the roof owners $1.00/ sq. ft. for their green roofs.  Later we charged $2.50/ sq. ft, and as the money and materials run out, we will try to approach a business model that is somewhere between $6.50 and $7.50/ sq. ft with paid labor and materials and a warranty.

The Guild’s Green Roof Project attempts to research each assembly component of greenroofs for the purpose of replacing proprietary components with generic or specified ones to lower the cost.  This approach applies to waterproof membranes, structure, drain mats, soil filter fabrics, soil mixtures, plants, erosion prevention measures, detailing, and general aspects of a business model.

hadj design has directed the greenroofing efforts for the Guild.  In 2002 we installed our first five green roofs consisting of garages, studios, and workshop structures with areas ranging from 900 SF to 250 SF and slopes from 1/4: 12 to 6.5 :12.  We used a variety of waterproofing membranes, from modified bitumen to modified rubber to TPO to EPDM.  We used a variety of drain mats, filter fabrics, soil mixes, and plant types.

This spring 2003 The Northwest EcoBuilding Guild completed another six green roofs with 15 more potential clients this year.  We have done about 11 public presentations and just completed our first hands-on workshop.  Later in the year we hope to present a business model for residential roofers, horticulturists, and other contractors laying out how a residential green roof business can operate.  Our research is slow in developing, but we will install rain water retention monitoring on seven roofs.  Hopefully with grants we will be able to monitor other aspects of green roofs like thermal behavior, water chemistry, acoustical characteristics, and ecological footprints of various assemblies.  And, of course, costs.

Above: NW EcoBuilding Guild sedum plants with erosion blanket; Below: Test Greenroof Panels; Photos Courtesy Patrick Carey

In addition to the green roofs we have installed, another 15 or so exist that have been built by others and the Guild hopes to include their information on our web site.  By the end of the year we plan to have a fully functioning web site; right now it is rather dated but still very informative.  We have the largest list of green roof plants on the web to my knowledge, and we hope to explain soil mixes so that they do not remain proprietary secrets.

Our over-arching goal is to promote an environment where the buyer of a house in a sub-division will have the option of getting a greenroof.  We feel the entire green roof industry is focused on the commercial market - why?  Because that is where the money is.

Unfortunately, commercial roof area is dwarfed by residential roof area; look at any zoning map and see for yourself.  If the green roof vendors want to live up to their rhetoric abut being green and ecologically conscious - instead of merely finding another application for their waterproof membrane products - they should come up with products and warranties that make a middle income residential market possible.  Until then they will remain silent when someone mentions a slope or a house.  We must keep in mind that virtually all the greenroof vendors in the U.S. are waterproof membrane manufacturers who initially hooked up with a German greenroof company.

I believe they may sound like they know a lot about green roofs, but are really only restating what the Germans have already researched and developed.

In addition to the invaluable help that the volunteers, the grantors, and our the generous vendors, such as Garland, American Hydrotech, W.P. Hickman, Invisible Structures, Excelsior Corp., GreenGrid, GreenTech, American Wick Drain, and Soil Moist, I would like to thank Linda Velazquez, Charlie Miller, and Professor John White for their generosity of information and spirit.  We also look forward to combining our work with that of another group, "Ecoroofs Everywhere" based in Portland, OR as well as a green roof builder in Spokane, WA to develop as large a data base as possible about residential green roof design and construction.  We hope through our research to test the claims of green roofs, from thermal efficiency to rain water retention.

In about a month we hope to have an updated web site with our most current information. 

So enough of the garages and studios already, it's time for houses!!!  This is not rocket science.  It simply is unfamiliar.

Patrick Carey is chair of the North West EcoBuilding Guild’s Eco-roof technical committee, has a degree in architecture and principal of hadj design.  For more about the Green Roof Project logon to www.hadj.net and select the Green Roof Project link or email Patrick at pkc@hadj.net.  Alternatively, you can log on to www.ecobuilding.org and select the green roof project that way.

See the related 2000 article ‘Green’ Buildings by Elizabeth Daniels of the Seattle Daily Journal of Commerce at NEWS LINKS.

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