Sustainable Practices

Ecoroof

Ecoroofs have been around for a while. Ecoroofs improve air quality by filtering airborne particulates, cool the air and reduce the urban heat island effect, and filter and cool stormwater runoff, thereby minimizing non-point source pollution. They also reduce energy consumption by insulating the building, provide habitat for pollinating insects, and generally improve the aesthetics of the building and surrounding neighborhood.

Friends of Trees' ecoroof has two parts: the roof of part of our office area, which is 420 square feet, and the roof of an adjacent tool shed, which is 80 square feet.

In addition to the ecoroofs, Friends of Trees planted a bioswale and directed our downspouts to a 1000-gallon rainwater harvesting tank. The ecoroof project was a retrofit, which meant that we needed to increase the load bearing capacity of our existing roof before we could construct and plant the ecoroof.

Friends of Trees volunteers were an integral part of the ecoroof project. They planted 700 drought tolerant Western Oregon natives representing 12 species.

Our Ecoroof Specifications

Total area: 500 sq.ft.
Roof pitch and type: 3:12 gable roof
Aspect: north and south
Waterproof membrane: torch-down bitumen
Drainage layer: AmerGreen 50 RS
Roof edging: custom prefabricated perforated 16-gauge galvanized metal with filter fabric
Growth medium: Pro-Gro Rooftop Aggregate 1-1 at 4" depth (custom soil blend containing pumice, perlite, digested fiber, paper fiber)

Native Plants

Total ecoroof weight (at saturation): 16-18 lbs/sq.ft.
Overflow: 1000-gallon rainwater harvesting tank (water will be used for irrigation on-site)

Our ecoroof is comprised of a waterproof membrane, a drainage mat, a four-inch layer of aggregate growing medium, and over 12 species of Western Oregon native plants. The growing medium, rooftop aggregate 1-1 from Pro-Gro, is a custom blend designed specifically for ecoroofs. It is composed of pumice, perlite, digested fiber and paper fiber and is extremely lightweight even when saturated. The plants are a terrific mix of native grasses, sedums, annual and perennial wildflowers that are drought tolerant. These plants will provide a beautiful display of color and texture year-round.

Frequently Asked Questions

Q: Why did you install an ecoroof?
A: We wanted to demonstrate an ecological roofing alternative to the community. This is consistent with our commitment to sustainability.

Q: How much did it cost?
A: Overall, the ecoroof and water tank cost just over $5,000.

Q: Where did funding come from?
A: Portland's Bureau of Environmental Services through a Community Watershed Stewardship grant.

Q: Won't the roof collapse?
A: We hired a structural engineer to assess the load bearing capacity of the existing roof. It was determined that some simple and inexpensive structural upgrades were necessary.

Q: Were permits required?
A: Yes, we applied for a building permit from the Bureau of Development Services.

Q: Won't the roof leak?
A: There is a waterproof membrane between the roof decking and the living roof system. Studies show that the waterproof membrane will last nearly twice as long as a traditional roof because the membrane is protected from damaging UV radiation and temperature extremes by the insulating layer of soil and plants.

Q: How will you mow the grass?
A: We selected native species that are low-growing.

Q: How will the plants survive?
A: We selected native plant species that are adapted to exposed dry sites.

Budget

Our Suppliers

Structural Engineers

Berry-Nordling Engineers
3607 SW Corbett Ave
Portland, OR 97201
Tel 503-227-7783

Plants

Squaw Mountain Gardens
PO Box 946
Estacada, OR 97023
Tel 503-637-3585
Fax 503-637-3580

Seed

Pacific Northwest Natives
1525 Laurel Heights Drive NW
Albany, OR 97321
Tel 541-928-8239
Fax 541-924-8855
cwe@proaxis.com

Soil

Pro-Gro Mixes, Inc.
P.O. Box 1127
Tualatin, OR 97062
26045 SW Grahams Ferry Rd.
Sherwood, OR 97140
1-800-682-3501
Tel 503-682-3500
Fax 503-685-9647
service@pro-gro.com

Drainage, Jute Fabric (for erosion control), & Synthetic Filter Fabric

ACF West Inc.
8951 S.E. 76th Drive
Portland, OR 97206
Tel 503-771-5115
Fax 503-771-1161

Metal Edging & Flashing

Rusch & Sons Metal Fab
4250 NE Killingsworth St.
Portland, OR 97218
Tel 503-281-3625

Roof Membrane Installation

McDonald & Wetle Inc.
2020 NE 194th Ave.
Gresham, OR 97236
Tel 503-667-0175

Water Tank

Tank-Depot.Com
Tel 727-5461790
Fax 727-545-2744
info@tank-depot.com

Prairie Landscape

With the addition of a prairie landscape in front of our office, we hope to increase habitat for native insects and animals, diversify urban landscapes with more native habitat, educate and demonstrate sustainable landscaping choices, and conserve and redirect rainwater.

Diversifying our urban landscape with pocket habitats of grassland/prairie plant cover increases habitat for most flora and fauna, which can translate into increases in insect pollinators. Benefits of pollinators include "enhancing fruit set and size, seed production and viability, seedling vigor, and the genetic diversity of plant populations" (Cane and Tepedino, 2001).

In the front of our office, our bioswale collects the excess water coming off the conventional part of our roof in the downspouts. We planted a variety of native grasses, sedges, and rushes in the swale to absorb the water rather than let it run off into the storm drains.

As homeowners and community members, we can have a positive impact on our urban environment. Restoring some urban settings to their pre-settlement vegetation communities enhances both plant and wildlife diversity in our urban forest. Benefits include improved air quality, cooler air in summer, reduced urban heat island effect, filtered and cooled stormwater runoff, reduced energy consumption from shade in summer and windbreaks in winter, increased habitat for pollinating insects, and generally improved neighborhood aesthetics. Please join us in this effort to diversity urban landscapes and improve the benefits of our urban forest community.

Native Plant List

*Non-native planted in swale