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Cross-Laminated Timber

Evaluating whether the Seattle Building Code should allow more height for buildings designed with cross-laminated timber.

What is Happening Now?

Our Seattle Building Code currently limits buildings made of wood products to no more than 85 feet in height and no more than 6 stories (depending on use of the building). With the aid of the Construction Codes Advisory Board’s (CCAB) Innovation Advisory Committee, we are deciding whether to allow bigger buildings built of cross-laminated timber (CLT).

CLT is an engineered product made of sheets of boards placed in layers perpendicular to one another in a manner similar to plywood. However, unlike plywood, CLT is made of thick layers of lumber with enhanced structural and fire-resistive performance.

Large CLT buildings have been built in other parts of the world. The Graphite Apartments in London is a nine-story CLT building, and a 10-story residential building, Forté is nearing completion in Melbourne, Australia.

Proposed Benefits

  • Carbon negative construction
  • Sustains local materials and industries
  • Reduces construction time
  • Cost competitive with concrete and steel
  • Clean and quiet construction process
  • Ideal for tight urban sites

The End Result

With the help of the CCAB’s Innovation Advisory Committee, we will continue to evaluate whether the Seattle Building Code should be modified to allow buildings designed with cross-laminated timber to achieve greater height.

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 Ask Us

Kathleen Petrie
Sustainable Codes Analyst
(206) 615-0541

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