Prefabrication experiments - 92 - Tall wood buildings

The merits of building industrialization and prefabrication have been related to waste reduction, efficient standardized processes and climate-controlled quality. Prefabrication reduces strain on both human and material resources. While concrete, steel and glass were the flagship materials of modern prefabrication, standardisation and industrialization, wood framing's age-old traditions of pre-cut components evolved into a lighter form of prefabrication. The wood balloon frame and the latter platform frame became synonymous with small buildings whereas steel embodied tall buildings as bridge building techniques were applied to mainstream construction during the 19^th century.

Today, construction and architecture are absorbing issues of sustainability through life cycle analysis, carbon footprint computations or green building strategies. The high- embodied energy production of concrete and steel are being questioned and the traditional techniques associated with tall buildings challenged. Particularly, massive timber construction is determining new directions for wood products in the construction industry. Responsible forest harvesting, advances in adhesive quality and in production methods and the need to reduce our carbon footprint are pushing production of innovative wood building technologies. From glue laminated beams and columns, to cross-laminated timber panels and laminated veneer lumber, wood is venerated as a sustainable building material. Wood products’ embodied energy can be substantially lower than concrete, steel or aluminum systems. Furthermore wood sequesters carbon over its service life.

Massive wood for tall buildings is being explored all over the world. Notably by Canadian architect Michael Green who published «The case for tall wood buildings» exploring massive wood construction techniques. Highlighting the various case studies is the use of cross-laminated timber panels in a type of massive wood panel construction, which compares to flat slab and bearing wall concrete construction in terms of spans and building system dimensioning. The cross-laminated timber panels are a form of hyper-plywood; vacuum bonded stacked layers of orthogonally crossed wood boards produce a somewhat isotropic (three ply minimum) panel from a fibre dependant base material.  Mass timber applied to tall buildings epitomizes the search for dense urban housing combined with an optimized material, an efficient production process and a simple panel and slab construction system. Tall wood is also gaining traction as regulating bodies, forest-rich countries and project stakeholders build the knowledge base for this new type of powerful industrialization for wood construction.

Excerpt from Michael Green's The case for tall wood buildings