g 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 footprint for timber buildings from responsibly sourced wood compared to steel, concrete and aluminium counterparts (the low energy used to make the building materials means reduced embodied energy);
lighter: resource-reduced construction with only a quarter of the weight compared with a concrete building, and significantly reduced waste;
the ease and affordability of heating and cooling a CLT dwelling, providing a healthy indoor climate (resulting in reduced operational energy and smaller energy bills for residents).
In the 1970s, off-site manufacture of building components led to industrialized uniformity and monotonous architecture. But Building Information Modelling (BIM), using computer-aided calculation and production methods, allows for a diversity of individual solutions (mass-customization). Accurate off-site prefabrication of CLT panels enables modular construction and enhances the use of efficient, digital design techniques. CLT wall panels can be precision cut off-site to create window and door openings and in some cases are already fitted with insulation, external cladding and windows. Prefabricated panels are also used for floors, roofs, ceilings, lift shafts and stairwells in some multi-storey buildings [46,47,48]. The review of cases in the scoping study highlighted the rapid on-site construction that may be as short as three to four months for buildings of up to nine storeys . Such short construction times, compared to traditional multi-storey construction methods, reduce noise impact, the risk of accidents on-site and the need for traditional construction equipment such as fixed cranes. CLT systems provide a precise construction process that allows faster completion, increased safety on site, less disruption to the neighbourhood and less waste. Traditionally around 40 per cent of all solid waste comes from construction and demolition. These benefits are not, of course, limited to CLT buildings but will be part of all modern methods of construction that utilize prefabricated wall, floor and roof con