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Courtesy: Bullitt Center
Glue-laminated timber (glulam) is a structural engineered wood element commonly used for beams and columns in residential and commercial applications. Glulam is a highly visible form of mass timber in contemporary projects, with long spans framing signature designs that have been left exposed to take advantage of wood’s natural aesthetic.
Glulam is stronger than steel at comparable weights, and it is stronger and stiffer than dimension lumber, according to APA – The Engineered Wood Association. That makes the material a cost-effective choice for long, structural spans and tall columns with minimal need for additional support.
Glulam can be used in interior and exterior applications. Several manufacturers sell glulam products with adhesives that can withstand moisture and wear from use outdoors.
To form a glulam component, wood laminations (dimension lumber) are positioned according to their stress-rated performance characteristics. In most cases, the strongest laminations sandwich the beam in order to absorb stress proportionally and ensure the member’s longevity, APA notes. The laminations are jointed end to end, allowing for long spans, and are bonded with a durable, moisture-resistant adhesive. The laminations’ grains run parallel with the member’s length to improve its strength.
Glulam members come in standard and custom sizes. Depths range from 6 inches to 72 inches, and widths range from 2.5 inches to 10.75 inches, according to APA. Components are cut to length when ordered and can surpass 100 feet. Commercial projects often require longer spans and accommodate bigger loads than residential projects, meaning custom widths and depths are often required. In addition to straight spans, glulam can also be used for curved and pitched applications.
Glulam is stronger than steel at comparable weights, and it is stronger and stiffer than dimension lumber.
—APA – The Engineered Wood Association
Four appearance grades—framing, industrial, architectural and premium—suit glulam for use in a range of architectural applications. Those include commercial buildings such as churches, higher education facilities and offices, as well as homes, where they offer a combination of structural and aesthetic attributes.
Glulam can work behind the scenes, too, as trusses, purlins, floor beams, cantilevers and other necessary structural elements, according to APA. Glulam has also found use as floor and roof decking planks. Elsewhere in the built environment, glulam can be found as a key structural element in bridges, poles and marina docks.
For its design of the Bullitt Center, a six-story office building in downtown Seattle, local architecture firm The Miller Hull Partnership picked mass timber, specifically glulam, over concrete for the structural frame. The material choice proved beneficial for this Living Building Challenge–certified structure due to its low carbon footprint and ability to be sourced locally and sustainably. Learn more about how the project’s glulam frame was executed in this case study. Read more.
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