 opportunity to turn building structures into ‘carbon sinks’. Contemporary technology has changed both the way in which timber buildings are converted and assembled , and how these can be protected against fire, insects and decay [34,35]. Wood is one of the oldest construction materials and one of the most utilized worldwide (more than steel and concrete) in construction . Given its carbon sequestration capacity, wood might well be the construction material of the twenty-first century. Engineered timber from managed forestry, from independently certified sources (i.e., PEFC, FSC), are likely to revolutionize the construction industry and become the material that makes sustainable construction in future possible [37,38,39].
The energy budgets of products and buildings made of wood show that they may use less energy over their total life cycle (manufacture, use, maintenance and disposal) than can be recovered from the waste products of their production and from their recycling potential at the end of their life cycle: they are energy-positive. No other construction material is so comprehensively energy-efficient and therefore climate effective as wood. (Wegener, Pahler and Tratzmiller, p. 4) .
3. What Is Solid Wood Panel Construction and What Advantages Does It Bring?
According to the Timber Development Association of Australia , a cross-laminated timber (CLT) construction system is a structural wood panel system fabricated by bonding together large timber boards with structural adhesives, alternating the grain directions of each layer, to produce a solid, load-bearing timber panel with each layer of the panel alternating between longitudinal and transverse lamellae. CLT is not just a ‘product’, it’s a building system. It has now become a recognised construction system increasingly used in Europe as an alternative to steel and concrete.
Large-format solid timber panels are engineered wood products used as massive load-bearing walls and floor slabs. First developed in Switzerland, Germany and Austria, CLT panels are 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 scopin