National/provincial impacts

Countries rich in forest resources typically benefit from a heritage of building with timber and the associated established skill base. Promoting the increased use of timber for buildings in such regions not only promotes economic activity and employment but also can generate significant additional benefits through further investment and innovation.

One of the first regions to heavily promote timber use was British Columbia, two-thirds of which is forested. The Wood First Act 2009 was introduced aiming to ‘facilitate a culture of wood by requiring the use of wood as the primary building material in all new provincially funded buildings’.³ This has contributed to British Columbia reinforcing its position as a global centre of innovative timber industries, with globally important CLT precedents as well as manufacturing expertise.

The French government decreed that 50% of all new French public buildings be built from wood or other organic material by 2022 as part of ambitious sustainability aspirations.

Forest industries and rural areas

Manufacturing and processing CLT are typically undertaken adjacent to or near to sawmills, close to sources of timber. This may be deemed a positive consequence for rural communities, adding value to material locally and creating employment opportunities. Considerations of how forest resources are managed shouldn’t be overlooked and are typically considered for timber sustainability certification purposes, albeit in particularly limited ways. However, an industrial scale, monoculture approach to plantation management can lead to significant biodiversity losses, particularly if land was previously mixed forest or under alternative use.

Increased timber use will also typically displace increasingly unpopular quarrying activities and extractive/industrial processes otherwise required to extract and process ore, limestone or aggregates.⁴

Regional/city scale

Mass timber use typically minimises vehicle movements, with far fewer vehicle movements for material deliveries and fewer workers on site (from 50 to 80% reductions, estimates vary). Concrete mixers may be required for foundations only and multiple panels are efficiently stacked in the factory on trailers to suit site access and logistics. Congestion, nuisance, pollution and risks to communities and neighbours as well road users, including pedestrians and cyclists, may therefore be reduced.

Recent discussions with a local government transport authority regarding an over-station development, potentially for their own occupation, highlighted such benefits. A huge increase in the popularity of cycling has led to an increase in cyclists’ deaths on the roads, frequently involving heavy goods vehicles. Any likely reduction in HGV movements through the city centre because of CLT construction was deemed to be a positive, particularly one that might lead to a significant and quantifiable reduction in risk to citizens.

Promoting the use of lower embodied carbon materials in the near future may also maximise the potential for the long-term economic success and value of an area. If other buildings fall out of fashion because they are deemed to be too high impact or no longer attractive to incoming owners or tenants, demand will fall and prices will follow while the chances of disruptive redevelopment occurring sooner increase.

Neighbourhood aspects

A shorter superstructure programme may significantly reduce disruption to existing neighbours. Construction sites, during frame erection, and for follow-on trades, are typically quieter without very noisy activities such as formwork placement, whilst generating significantly less dust and enabling hot works that create risk or wet trades that slow down subsequent work to be reduced to a minimum or even eliminated entirely.

Comparatively little laydown space is required during construction whether panels are lifted directly from trailers or stacked on site. As such, neighbourhood impacts of site hoarding on pavements, highways and public spaces may be comparatively limited. Such aspects are of particular relevance to high-density urban environments where increased proximity to a site frequently amplifies neighbours’ concerns, whether relating to perception or actual disturbance.

Social aspects for construction site labour

The installation of pre-manufactured components has a very significant social impact beyond the safety issues discussed in Chapter 11. The numbers of superstructure workers required for a CLT frame is typically a fraction of that required for alternatives and they are needed on site for less time since frame construction can be much faster (again, greater benefit may be felt on high-density, busy sites).

Follow-on trades have also reported significant improvements in their working environment with a resultant improvement in outlook from warmer, quieter and cleaner sites where trades are happier working. Providing easier work as well as a significantly better working environment is a very good way of encouraging safer and better quality outcomes whatever the work package. Anecdotal evidence of subcontractors completing work earlier than planned because of improved conditions is not uncommon (but this can also adversely affect site programming if not planned effectively).

Benefits for owners, occupiers and users

Benefits for occupants and users may include: high quality internal environments and efficient energy performance due to relatively high performance of CLT envelope construction with limited uncontrolled leakage potential; the hygroscopic action of exposed surfaces; long-term value or exposure to natural forms or biophilic elements. Some may appreciate the feel-good factor (or bragging rights) of being associated with cutting edge and low impact buildings, particularly when the impacts of more aspects of our lives are coming under ever increasing scrutiny. Custom build participants and those commissioning private homes may appreciate the speed of construction and certainty in installed quality.