The wonders of wood
Discipline Director Andrew Wylie specialises in engineering with timber and timber hybrids. With the recent rise of timber hybrid construction he explains what it is about timber that makes him so keen on championing its use in construction.
One of the things I love most about building with timber is how interesting the resulting buildings can be, creating such exciting forms. One of the first timber buildings that grabbed my attention was the Weald and Downland Gridshell building in West Sussex, shortlisted for the Stirling Prize in 2002. It was the first gridshell building of its type to be built in Britain, and was designed by BuroHappold and Edward Cullinan Architects, not long before I joined the firm. Thinking back, it probably played an important part in making me keen to work here.
I have a long interest in timber construction – it was actually the subject of my Masters thesis some time ago. Wood is a product that has been used successfully for centuries but, but with the rise of steel and concrete technology it fell out of favour as a mainstream construction material, given that steel and concrete were better at addressing fire and durability challenges.
Now, though, we know that timber has far greater potential. There’s more to timber than chopping down a tree and milling it into simple stick elements. Knowledgeable design and new timber products make it possible to overcome challenges such as rotting and combustibility. Timber can be processed to make products that are really reliable for construction: hybrid products like cross-laminated and glue-laminated timber.
We think of these as fairly modern products, but glue-laminated timber was first used back in 1866 – on the sports hall at King Edward’s College, Southampton. It didn’t really take off until the late 20th century. Cross-laminated timber has come into its own more recently, in the past 10 years or so.
Stihl Treetop Walkway at Westonbirt
Combining materials to get the result you’re after is an old idea – think of cob walls and masonry-panelled buildings. But as material suppliers have specialised in single materials, say steel production, there has been a tendency – certainly in the UK construction industry – to be a bit blinkered and build with single materials. For hybrids to become a real possibility, contractors and suppliers have to be prepared to coordinate construction in multiple structural materials. As clients become more aware of the need to reduce carbon use, developing more of a conscience about sustainability and carbon consumption, we’re being asked to do more and more work with timber. We are one of relatively few firms with experienced timber engineers, so we’re able to use our knowledge and expertise to work with architects to realise clients’ dreams, even if architects haven’t used timber before. Designing and building with timber doesn’t have to be scary and challenging.
Savill Building in Windsor Great Park
Timber enables us to design incredible, iconic timber constructions that make the most of the unique features of wood – for example, the Savill Building in Windsor Great Park and the Stihl Walkway at Westonbirt Arboretum. But it also has practical uses and could be used a lot more. When we worked on the refurbishment of the Royal Shakespeare Theatre in Stratford-upon-Avon, the use of timber provided an answer to a particular challenge. The foundations were tricky to build, so finding a lighter way to build was transformative. Using a steel-frame with cross-laminated timber was lighter and cheaper, too.
What started as niche is becoming more mainstream. In fact, I believe it could be taken further: this type of solution could and should be consider for all build types and scales. At BuroHappold, we are always keen to pursue new challenges, and timber is one of the areas in which engineering structures can push boundaries.
“I’m thrilled that our Tree Management Centre for Westonbirt Arboretum won three RIBA Awards: this is a testament to a remarkable project. The engineering by BuroHappold was deceptively complex: the main timber structural members are possibly the biggest ever in UK construction (certainly for 150 years), and very few engineers have the nous like Andrew Wylie and Graham Clarke to understand how to use the unpredictable, ungraded, unprocessed, untreated timber directly from site. The Sustainability Award that we won is testament to their thinking.”
Piers Taylor – Invisible Studio
The Wolfson Tree Management Centre at Westonbirt Arboretum
A lot of exciting things are happening in timber engineering now. One of my favourite recent projects was the Wolfson Tree Management Centre at Westonbirt Arboretum. The Wolfson was built entirely from timber available at Westonbirt, and was processed on site – a green solution. As Corsican Pines were the trees being harvested at that point, they were the trees we used for the construction. They influenced the shape of the building and the way in which it was engineered. A rather lovely feature is the way the specimen numbers (all trees in the Arboretum are numbered) have been incorporated into the Wolfson.”