How to make cross-laminated timber work for your development
CLT is risky acoustically, but with the right advice it can yield impressive benefits for developers
If you haven’t heard of cross-laminated timber yet, watch this space. The light, stable and strong building material has a fast-growing reputation as an attractive commercial alternative to concrete and steel. But what are the risks for developers?
Sometimes described as super-plywood, cross-laminated timber or CLT is made by gluing sections of timber together to create blocks which can be cut down into custom-sized panels.
CLT has many advantages over conventional building materials. With a carbon footprint half that of concrete and natural thermal insulation properties, it’s sustainable and energy efficient. It’s also lightweight, which dramatically reduces construction times, and its modular construction has seen CLT deployed globally from small-scale constructions to large high-rise developments.
But – it can also be very noisy!
CLT requires specialist interventions to meet noise and vibration standards. Take for example the Green Building Council of Australia’s Green Star acoustic standards. CLT creates several challenges for developers:
- CLT slabs do not provide particularly good sound insulation compared to concrete, making Green Star v1.3 IEQ10.3 more difficult to achieve.
- Exposed CLT soffits and floors look great, but provide no reverberation absorption, making Green Star v1.3 IEQ10.2 more difficult to achieve.
- Exposed CLT slab ceiling systems often don’t include an enclosed ceiling space. This potentially leaves mechanical services exposed and raises internal noise, making Green Star v1.3 IEQ10.1 more difficult to achieve.
- Even footfall noise, not typically an issue in commercial development, can require additional acoustic treatment to avoid one space creating excessive noise and vibration impacts for downstairs tenants.
Drawing on our acoustic expertise, Renzo Tonin & Associates has developed innovative design responses to the design limitations of CLT.
This includes our work on Lend Lease’s Forte project, the world’s tallest timber apartment building. The Forte building is 10 storeys high – but took just 10 weeks to erect. On some estimates, using a more traditional concrete structure would have added four months to the project. Having expert acoustic advice meant Lend Lease could take advantage of the commercial benefits of CLT, whilst still complying with sound isolation standards.
Before the Forte project, CLT technology was unproven under Australian conditions including National Construction Code and Building Council of Australia requirements.
Renzo Tonin & Associates worked closely with Lend Lease during the design and construction stages to develop and implement cost-effective floor, ceiling and wall solutions. A rigorous program of on-site inspections and testing monitored for defects and then later certified that the resulting sound insulation performance fulfilled the project brief.
The success of this project has led to Renzo Tonin & Associates and Lend Lease working together to successfully deliver further CLT projects including the Library at The Dock and the Docklands Boating Hub.
We advise many developers on CLT. Projects we’ve assisted other clients with include:
- Taronga Zoo Wildlife Retreat
- Lexington Gardens Retirement Village, Clayton
- GTV9 Central Precinct, Richmond
With the right advice, you can take advantage of the benefits of this dynamic new building structure. We can help you weigh up the relative benefits of using CLT against conventional or hybrid construction methods.