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 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.
We will continue further evaluation to determine if the Seattle Building Code should be modified to allow buildings designed with cross-laminated timber to achieve greater height.
Sustainable Codes Analyst