Cross-laminated timber (CLT)

Cross-laminated timber (CLT) is a structural mass-timber panel made from layers of boards stacked crosswise and glued under pressure, used as solid floor, wall, and roof elements. It is one of the engineered mass-timber products (alongside glulam and LVL) that let timber do jobs once reserved for concrete and steel.

How it is made

CLT is built up from an odd number of layers (commonly three, five, or seven), each layer laid at right angles to the one below, then bonded into a single rigid panel. The crosswise layup is the whole point: it makes the panel span and carry load in two directions and stay dimensionally stable, where a single board or a one-way beam would move or only span one way. Panels are cut to size in the factory, with openings, services, and connections set out, then craned into place, so CLT is a prefabrication system as much as a material.

Where it differs from framing

CLT sits outside the AS 1684 span tables, which cover light timber framing. A CLT panel is an engineered element: it is designed to the manufacturer’s technical data with a structural engineer’s input, not picked off a span table. That is the same path as other engineered products like LVL and structural plywood.

For a builder

It is engineer-and-supplier territory. Sizing, connections, and fire and acoustic detailing come from the CLT supplier’s system and the engineer, not from AS 1684. Bring them in early.
It is a prefab workflow. Panels arrive cut and numbered; the program is about crane time, sequence, and connection hardware, not on-site framing.
Mind moisture on site. A thick panel must be kept dry through transport, storage, and erection; trapped moisture is a real problem, so weather protection and a drying strategy matter.

Also known as: CLT, X-lam.

How it is made

Where it differs from framing

For a builder

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