Engineered timber: structure that stores carbon

Prefabrication moves decisions forward, so the site assembles what the team has already resolved. Panels arrive in sequence and are connected dry. At Brock Commons nine installers assembled an 18-storey superstructure in 70 days; a US redesign study reports savings of up to 3.5 months on high-rise structures.

Over its whole life a timber frame carries less embodied carbon than a concrete or steel frame, though the results overlap and depend on design. Wood also holds the carbon the tree absorbed for as long as the building stays in use, if the forests are sustainably managed.

A timber frame weighs a fraction of the equivalent concrete frame. Less weight can mean lighter foundations and fewer heavy deliveries, depending on the site.

A light structure attracts smaller seismic forces. A seven-storey CLT building was shaken with the 1995 Kobe earthquake record on the world’s largest shaking table without significant damage; the authors note relatively high accelerations in the upper storeys as a point for further research.

Boards are graded and checked for moisture, glued under controlled conditions and cut by machine for windows, doors and stairs. Panels reach the site as finished elements.

Dry assembly means little cement mixing, heavy plant and dust on site, and fewer truck movements through the neighbourhood. The evidence is indicative: it comes from industry guidance and project accounts, not independent studies.

A systematic review of nine randomized trials found that longer exposure to visible wood tended to improve mood and lower physiological arousal, though the results are not fully consistent. Timber’s thermal mass can also moderate indoor temperature, as two years of monitoring in a five-storey CLT hotel suggested; the benefit depends on climate and design.

Engineered timber is no longer experimental: Brock Commons in Vancouver has 18 storeys, HoHo Wien in Vienna 24 storeys and 84 m, and Austria alone produced almost 700,000 m³ of CLT in 2024.