Question: How do you make a 25 foot long, flat, green salmon?
Answer: Get a big, sloped, solid roof. Add 24 tons of growth medium of lava, pumice and other good stuff. Bring in a half dozen experts to plant the perfect plants, with an emphasis on the fish shape. Wait for summer.
The Hatchery’s roof has been designed to carry a heavy load. Even so, the decisions for planting the green roof had to be carefully considered. Overall, the dirt layer is just 3 inches, sufficient for succulents and shallow rooted plants. A deeper layer (some six inches) was placed over the load bearing wall to create a raised ‘fish’ shape. The fish is outlined with rocks and planted with ferns to contrast with the rest of the roof and, hopefully, will be visible from space.
Having a fish on the roof is fun, but there was a more serious basis for deciding on a green roof for the Hatchery. The roof has been carefully designed for efficient insulation, using a 6” base insulation in combination with a green roof system. The advantages are several:
Significant extension of the lifespan of waterproofing membrane: Using the combined insulation and the green roof layers, the roof membrane is no longer exposed to UV and temperature fluctuations. These are the primary factors that cause roof deterioration. With this system, we can expect 2-5 times the normal lifespan for the roof membrane.
Cooling the building’s interior: Green roofs reduce the heat transfer through the roof by up to 85%, making the inside space more comfortable. This also reduces cooling costs during hotter weather.
Biodiversity and habitat: The green roof has been planted with mosses, stonecrop, wild strawberries, lingonberries, ferns and more, providing a habitat for bees, insects, and birds.
Storm-water mitigation: Because the green roof holds water, it reduces run-off and potential damage from run-off. This is less critical for the Mossom Creek hatchery, given its location, but is a key benefit in dense urban areas where green roofs can play an important role in mitigating damage from storms.
Mossom Creek Hatchery’s green roof has been installed. Give it a few months and try Googling it to see the fish!