Frequently Asked Questions
about Cross-Laminated Timber (CLT)
Q: What is Cross-Laminated Timber?
Cross-laminated timber (CLT) is a mass timber product used as an alternative to commonly used building materials like steel, masonry or concrete. It is an engineered wood panel typically consisting of three, five, or seven layers of dimension lumber oriented at right angles to one another and then glued to form structural panels with exceptional strength, dimensional stability, and rigidity.
Q: Where is CLT used in construction?
Because of CLT’s structural properties and dimensional stability, this mass timber product is well suited to floors, walls and roofs used in mid-rise construction. The wall and floor panels may be left exposed in the interior, which provides additional aesthetic attributes.
Q: How are the panels engineered and how large are they?
The panels are used as prefabricated building components, which can speed up construction practices or allow for off-site construction. At D.R. Johnson, the beams can be engineered in the production mill as large as 98 feet long, 18 feet wide and 19.5 inches thick.
Q: Is CLT certified and, if so, under what standard?
D.R. Johnson is the first U.S. manufacturer of cross-laminated timber to be certified under a new standard approved last year by the American National Standards Association. The standard, ANSI/APA PRG 320-2012 Standard for Performance-Rated Cross-Laminated Timber, details manufacturing and performance requirements for qualification and quality assurance. Thanks to recently approved local building code changes, CLT has also been included in the 2015 International Building Code (IBC). The ANSI/AWC NDS-2015 National Design Specifications for Wood Construction was approved as an ANSI standard in September 2014.
Q: What U.S. projects are being planned with cross-laminated timber as a building material?
View the interactive map here.
Q: Where can I find more technical information about cross-laminated timber?
Detailed information about CLT can be found in the U.S. CLT Handbook. The handbook details the manufacturing, structural design, connections, fire performance, sound quality, environmental performance and lifting & handling requirements of CLT.