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What is a Green roof?

In 2004 Tilth, installed a green roof in our Wallingford demonstration garden. Learn more here!

Seattle Tilth Green Roof

Green roofs are vegetated roof covers, with growing media and plants taking the place of shingles or tiles. Also called eco-roofs, living roofs, and roof gardens they are an innovative stormwater management solution that can simultaneously improve the energy performance of buildings, air quality and urban ecology-- all without taking up additional land.

A green roof system involves a special water proof and root repellant membrane, a drainage system, filter cloth, a lightweight growing medium and plants. 

Benefits of Green Roofs

  • Reduce the volume of stormwater flowing into streams and drainage channels
  • Absorb pollutants, cool and clean rain water, decreasing thermal pollution and toxins that flow into our waterways
  • Provide better insulation, a shaded roof surface helps to cool the building in the summer and acts a blanket to help conserve warmth in the winter. 
  • Reduce the urban “heat island” effect. On warm summer days a city can be 6-8 degrees warmer than it’s surrounding areas due to the heat it is reflecting. Green roofs cool the air by reducing solar radiation and by evapotranspiration, where plants emit water through pores in their leaves which cools the air in the process. 
  • Help insulate from noise by reducing the sound penetrating a roof and the sound being reflected from the roof.
  • Convert carbon dioxide from the air into oxygen that we can breath.
  • Provide habitat for diverse plant and animal species, including beneficial insects and songbirds


Visit Tilth's Green Roof

In 2004, Tilth constructed a green roof on the roof our greenhouse in our Wallingford Demonstration Garden.  This project was funded in part by a King County, Department of Natural Resources and Parks, Water Works grant.  See our living roof in action by visiting the Wallingford Demonstration gardens.

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