Seattle Green Code Provisions Focus on Landscape Irrigation


The City of Seattle announced a list of proposed high efficiency building code changes, entitled Green Code Provisions.

"The green code provision for 2012 focus on long-term green priorities, such as water conservation, material conservation, sustainable transportation and healthy landscapes," say its drafters. "Some examples include promoting salvage instead of recycling, tightening up water irrigation and using more efficient hardware for buildings."

Here is a list of provisions for all new or replaced in-ground irrigation systems

Landscaped areas less than or equal to 30,000 square feet shall be equipped with a rain sensor device. Sprinklers shall:

. Use low precipitation, high distribution uniformity rotary nozzles. Have nozzles with matched precipitation rates.
. Have a separate master valve or a combination of a master valve and pressure regulator.
. Have heads with internal check valves.
. Pop-up to a height of not less than 4 inches if of the pop-up configuration.
. Have flow sensors on installations of 30,000 sf or more of irrigated area.

Landscaped areas greater than 30,000 square feet shall also comply with the following:

. Shall be designed and installed by an accredited irrigation professional.
. Water shall not be directed onto building exterior surfaces, foundations or exterior paved surfaces.
Systems shall not generate runoff.
. Shall be WaterSense labeled.
. Irrigation zones shall be based on plant water needs with plants of similar need grouped together
. Micro-irrigation zones shall be equipped with pressure regulators
. Drip irrigation systems shall be used to irrigate "shrub species."
. Sprinklers shall be prohibited on landscape areas less than 12 feet in any dimension.
. Sprinklers shall only be installed in zones composed exclusively of sprinklers and shall be designed to achieve a lower quarter distribution uniformity of not less than 0.65. Sprinklers shall be prohibited in areas with a 25 percent slope or greater.

Also, Invasive Species and Native Vegetation (Regional Plan) draft provisions for all new vegetated landscapes or those existing invasive plant species shall be removed and no invasive species planted. 75 percent of all new plantings will be native to Western Washington, a vegetation plan must be submitted for review and Existing native plants shall be protected whenever possible.

View the draft Green Code Provision at the Washington State Nursery  and Landscape Association website at