 an extension of the technology that began with plywood and may be best described as ‘jumbo plywood’, where layers of timber, known as lamellas, are glued together with the grain alternating at 90 degree angles for each layer (thus different from LVL or glue-lam). Cross-laminating layers of wood veneer improves the structural properties by distributing the along-the-grain strength of wood in both directions, and this means that solid wood panels can be used to form complete floors, walls and roofs. The advantages this offers are quite exciting—timber panels are much lighter than concrete, more easily worked and easier and safer to erect [42,43,44]. In addition, it is well-known that a timber-based construction can withstand fire far longer than a steel building, which when softened by heat might suddenly collapse, whereas a burning wooden beam can more often still support a cross-section of sufficient load-bearing capacity for long enough to evacuate a building.
CLT construction technology for multi-storey residential buildings was further developed in Europe in the 1990s and has been widely used in European countries (e.g., produced under the names Brettsperrholz or Massivholz, by highly qualified medium-sized manufacturers and imported to other countries, such as the United Kingdom) as a modern construction method. More recently this construction system has been adopted by Canada and New Zealand, utilising opportunities for industrialised offsite construction methods.
A recent scoping study identified the research needed and existing capacity to deliver solid wood panel buildings for infill development in Australia using CLT construction systems . Key stakeholders were interviewed for their perspectives about CLT including the perceived barriers to and/or opportunities for using CLT buildings and establishing CLT construction systems in Australia. There is still some confusion between acceptance and skepticism (consumer resistance) about the introduction of CLT apartment buildings in Australia.
While the scoping study reveals a keen interest in and willingness to adopt CLT systems for multi-residential development between architects, the main barriers are: a lack of local manufactured product with which to enhance familiarity; uncertainty about gaining building approvals for fire performance (including prevention of fires during construction); and the social acceptance or liveability of timber buildings for infill development by potential occupants . Other barriers to CLT constructions are perceived disadvantages of wood as a building material because people are afraid that it might lead to higher maintenance and could lack durability (usual concerns include fire, acoustics, moisture and vermin protection): it requires protection from insects, such as termites, or fungi, and it could be exposed to decay or rot. However, the technical challenges are widely resolved. Provided there is a rain screen facade protecting the timber panels, condensed water will dry out. Overall, timber is a highly resilient and flexible, natural re-growing building material.
There are a number of clear benefits of solid wood panel buildings, such as the ones built with CLT. The following list is drawn from our own review of such buildings, a review of research papers, of wood product industry strategies and from discussions with industry stakeholders in the supply chain:
the speed with which the structure of CLT constructed buildings can be assembled on-site (built at least 30 per cent faster, because much of it is prefabricated and lighter);
the acoustic and thermal performance of massive CLT panels, which potentially reduce the level of additional insulation needed for energy efficiency and sound deadening;
the expected higher fire performance of CLT compared to timber-framed buildings (high-density massive wood panels char rather than ignite, and the charring creates a fire barrier, as the charred layers protect the panels’ load-bearing capacity);
storage of carbon in the timber of each CLT building (CO2 sequestration);
a reduced carbon foo