Exposed CLT faces new challenges
April 12, 2017
Nick Hewson is overseeing an innovation in CLT construction where the CLT in a new apartment block will be visible – raising a range of fire and acoustics challenges.
The technical manager for XLam Australia, Nick will explain these design issues with a presentation on “Engineering design for mass wood residential buildings” at the Frame Australia ‘Timber Offsite Construction’ conference in June.
XLam are currently building Australia’s first CLT plant in Wodonga which will be one of the most technologically advanced CLT plants worldwide.
With a background in structural timber in the UK, Mr Hewson said working with CLT involved more than structural engineering. “It needs a multi-pronged approach to come up with the best solution. A co-operative effort is where the solution lies,” he said.
That’s why the case study he will use to illustrate the challenges – the six-storey Nightingale apartment project in Sydney Rd, in the inner Melbourne suburb of Brunswick - is an apt example.
It is the brainchild of a group of collaborating architects who are not working with developers, but forging ahead on their own. “The particular focus is on the end-user – the people who will live in the apartments, with sustainability high on the agenda,” he said.
“It’s the first project where an aim is to expose CLT internally so you can see it. Usually timber is clad with plasterboard, so when exposing the timber, it’s obviously working that much harder in a fire” Mr Hewson said.
This visibility in turn has implications for acoustics. “Because we want to expose ceilings in the apartments, we must compensate with the top of the floor to achieve acoustic ratings,” he said.
Then there is the external façade. The Nightingale will sit between existing buildings along Sydney Rd. “It’s difficult to get access and scaffold. We are trying to develop external wall systems so we can pre-clad,” he said.
“That’s probably what we will see more of in CLT buildings going forward – more pre-clad, to eliminate the need for scaffolding.”
No decisions have been made on the material for cladding, but he said the fire issues around cladding had become awkward to deal with in commercial buildings, particularly after the tower fire in Docklands when external cladding ignited.