Learn about mass timber, CLT and hybrid systems

Tall wood buildings are constructed using mass timber products such as glued-laminated timber, cross-laminated timber (CLT) and other large-format timber products. Conventional stick frame construction (e.g. 2×6 studs with floor joists) is not mass timber. The large-format products resemble the solid sawn heavy timbers that were traditionally used by timber framers over a century ago. Cross-sections of 12”x12” (30 cm x 30 cm) are not uncommon for columns, for example. The components are prepared using automated CNC machines which can cut within 1 mm of tolerance – much tighter than typical construction tolerances. The components can be used for the walls, floors and roof of a typical tall wood building. Gravity (self-weight, occupancy and snow), and lateral forces (from wind and earthquakes) are resisted entirely by wood-based structural systems.

At present, there is not one defined system in practice. This is an emerging field and new mass timber ideas are being proposed every few months.

Hybrid systems are also being built. Hybrid structures combine mass timber with other materials in different parts of the structural system. An example of hybrid system would be a building with steel columns and wood floors. Some buildings have concrete elevator and stair shafts with the rest of the structure in wood. Each system has its benefits and drawbacks across many variables. Many of the benefits are related to thinking of construction with a mind to manufacturing in a very modern sense.

Time will tell which system, whether in pure mass timber or hybrid, will become the frontrunner and preferred choice of designers and builders.

Are you new to mass timber and tall wood buildings? Learn more here.