Theo Pasialis, director of building company Holz DC explains why more architects need to design buildings that have frames made of Cross Laminated Timber (CLT).
Why do you think more architects should design buildings with CLT frames?
Most advocates will highlight the speed of construction that may be achieved with the use of CLT. This obviously is a consideration for the architect and the client. Other benefits that I believe should steer architects to the use of CLT are:
- The cost savings achievable for the client without compromising design, in fact I would argue the design would be enhanced through the use of CLT.
- The aesthetic qualities achievable through the use of different grades of CLT finishes.
- The much lighter weight of massive timber in comparison to concrete, and yet still achieving a solid construction that can outperform concrete and steel in many aspects of consideration.
- The prefabrication aspect ensures that on-site work is minimised in terms of the number of people on-site, as well as the duration of building works affecting neighbours. There are also safety benefits, due to the reduced number of workers and duration on-site. Noise levels during construction are also reduced.
- Lastly, wastage is minimised due to the structure being prefabricated and fitting together perfectly.
How does CLT relate to increased sustainability?
As a wood product, CLT is a totally renewable carbon neutral construction material, boasting the lowest energy consumption of any other building product. It’s cited as the 21st century solution to building sustainability. It’s generally more cost effective than structural steel or concrete, and vastly outperforms conventional framed construction materials for airtightness, thermal insulation, internal moisture management, acoustic insulation and fire resistance.
What are the main limitations of designing and building with CLT-framed structures?
The limitations are minimal, which is a benefit in itself. But I would say one limitation is the lack of knowledge or education about CLT amongst various stakeholders in the construction industry. This will certainly change with time, but at the moment, more investment in educating architects, engineers and other consultants is necessary in Australia to understand the benefits of CLT and how to design accordingly.
Another limitation currently would be the BCA ‘DTS’ provisions and performance solutions for CLT needing to be brought up to speed, as it can act as a ‘speed hump’ for multi storey buildings. The last limitation would be the span of CLT in comparison to a concrete post tensioned slab, which could be viewed as a limitation for use in a large building where large unobstructed spans may be a requirement.
Should more architects be using CLT in their designs and if so why?
To put it simply, yes, we think architects should be using CLT in more designs for many reasons. Wood as a material evokes warmth and security. Any person who has been inside a CLT building will experience this. I vividly remember this when I was inside my first CLT building and compared it to the ‘cold’ feeling from a concrete/masonry building.
The low energy construction leads can have a direct effect in reducing operating costs for a building and CLT has a very low thermal conductivity compared to other materials. CLT also provides a healthy and comfortable living climate due the room temperature, air moisture and noise levels.
It’s especially suited to construction in seismic areas, allowing buildings to withstand the seismic loads far better than other forms of construction. Most importantly, numerous studies in Europe have shown how working, studying or living in a timber environment has measurable psychological and health benefits. Schools, nursing homes, office buildings all benefit from the use of CLT.