3. Is timber versatile?
Timber offers many advantages, and versatility is very important. “Its thermal insulation properties make it energy efficient, and it is economical and fast to construct,” says Ove Morten Bergane, head of structures for WSP in Norway. “It is ideal for prefabrication, simple and quick to install, and very flexible.
Thanks to timber, WSP’s structures team in Norway overcame a number of challenges in the design of a student apartment building in Haugesund, which has distinctive architecture with slope CLT walls, slices and different shapes. The ground floor is for business areas with open spaces. The floor above is made in concrete and CLT above this level. The project meets passive house standards and is an infill project in the centre of the municipality.
“The light weight of timber makes it ideal for over-building as our cities get ever denser and space is at a premium,” adds Phil Gardiner, principal director based in Melbourne, Australia. “We’ve designed a residential building on top of an office tower; and an office tower above a shopping centre, which would require almost no strengthening of the structures on the trading floors. We are currently designing a ten-storey CLT hotel in Melbourne that will be built over a railway line.”
Furthermore, wood is easy to handle on the construction site. There’s no hard drilling, which makes the construction process quieter, and cleaner, for everyone.
4. Is timber design friendly?
Timber is extremely easy it is to work with, especially when offsite construction is part of the equation. Cross laminated timber (CLT) panels – or ‘2D elements’ – consist of three to nine layers of timber, each glued perpendicular to the one below. These 2D elements work like concrete, but are quicker, easier and safer to manufacture offsite. With digitalisation, the different components can be precisely fabricated according to specifications, and easily assembled on-site.
“We can use a hybrid floor plate that has steel columns and beams but replaces a composite deck slab with a cross-laminated timber slab manufactured off-site. The timber makes an aesthetically pleasing ceiling for people on the floor below, services can still run as they would in a traditional solution and – with no waiting to fix reinforcement, pour concrete and allow it cure – construction is faster”, explains Dan Hagan, technical director and Modern Methods of Construction Lead for WSP in the UK.
In addition, by moving construction into a controlled offsite manufacturing setting, we can address reliability, quality issues and provide certainty in design programming and cost.
5. Does timber make economic sense?
Last but not least, cost. Sure, mass timber can be more costly when compared to steel or concrete on a per unit basis. However, when looking at the whole picture, timber makes the cut.
- Thanks to its light weight, timber allows for smaller foundations and fewer support structures.
- Manufactured components and ease-of-use means timber necessitates smaller crews, leading to reduced labour costs.
- Using timber can speed up construction time potentially resulting in schedule savings of 20-50% than if traditional materials are used.
Dan Hagan adds that timber is an excellent option for retrofit projects that involve adding floors to existing buildings. “A multi-storey mass timber building has a substructure up to 85% smaller than a traditional alternative. This reduction in substructure material relates directly to a similar saving in costs, programme, and importantly, embodied carbon”, he says.
And ultimately, timber buildings have other financial benefits that are more difficult to calculate, such as improved health and wellbeing for occupants and higher staff retention (or lower staff turnover) thanks to attractive work environments.
Timber might be one of the oldest building materials, but we are still learning how to optimise its potential. WSP experts across the globe collaborate to increase our understanding of the challenges and opportunities for timber, and explore its use as a sustainable, healthy, safe and efficient alternative to concrete and steel.