In April 2012, the City Council Planning Land Use and Sustainability Committee was briefed on a novel proposal for use of a new wood product in building construction. DPD is reviewing this proposal that would allow buildings using this wood product to be several stories taller than is allowed by the current (and past) building code.
- Wood: Concrete for the 21st Century – Presentation to Council
- Why Not Timber High-Rises? – Appendix to Presentation to Council
The product being introduced to the market is called cross-laminated timber, or 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. 
The Construction Codes Advisory Board’s Innovation Advisory Committee is evaluating whether Seattle should increase the height and area allowed for buildings built of CLT. 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.
For more information, read the New York Times article “Wood That Reaches New Heights.”
Contact Kathleen Petrie at firstname.lastname@example.org to participate in committee activities, or to receive periodic project updates.
 The technical definition of cross-laminated timber is “a prefabricated solid engineered wood panel made of at least three orthogonally bonded layers of solid-sawn lumber or structural composite lumber (SCL) that are laminated by gluing of longitudinal and transverse layers with structural adhesives to form a solid rectangular-shaped, straight, and plane timber intended for roof, floor, or wall applications.” ANSI/APA PRG 320-2011, Standard for Performance-Rated Cross-Laminated Timber.