Just after midday on Friday 16 November 2018 Andrew Payton
and his crew from AJP Constructions ran
their tape from one end of the building to the other. They were taking the final measurements of the
CLT panels installed on their Bellevue Hill renovation. Their timber framing for the first-floor
extension was complete.
They are now three months ahead of schedule.
The building was less than 1mm longer than the documented
dimension, in fact it was as close as you could get to perfect, perhaps even
more accurate than the tape itself. And
every panel was perfectly plumb. The
rest of the build was going to be simple.
To Andrew the savings were obvious – both time and real cost savings have been realised immediately. As Andrew himself says:
"The CLT panel installation was undertaken in 22 hours over 3 days. With traditional timber framing I estimated that this would have taken between 2 and 3 months and another few weeks of packing the walls to straighten and level before installation of the plasterboard. There were definite savings on the overall cost of the construction"
2 days earlier, 50 pieces of CLT panel with a total weight of just under 26 tonnes
or 50.8m3, including 24m2 of H3.2 treated panels had started to be installed, in the end using over
3000 Rothoblaas screws and brackets. A total of 22 hours of crane hire facilitated the install. At the end of each day a moderate amount of
work was needed to do setout and packing, 8 hours in total, Andrew estimates, over two days. The first four of six pallets of CLT had arrived on a
semi-trailer on the tree lined street in Bellevue Hill two days earlier. John the truck driver had driven up from the
XLam factory in Wodonga on Tuesday night and spent the night in Albion Park. Early Wednesday morning he made his first
delivery. He drove back to Albion Park
Wednesday afternoon and delivered the last two pallets on Thursday morning. The first three CLT pallets were installed on the first
day. Two more pallets on the second day
and the final pallet on the third day.
Less than a month before the delivery the final approval of
the CLT shop drawings from XLam was complete by AJP Construction, Sago Design and
Cantilever. All the timber for the CLT came from local forests in NSW and
Victoria and is delivered to site with an FSC rating. The panels are manufactured by XLam and,
unlike imported bulk CLT panels from overseas, each panel is made to
size. This results in almost no
wastage. The panels are then put through
the CNC machine in the XLam factory and placed on the flatbed. It would be challenging to build a more
Just over 12 months earlier, Lachlan from Sago Design, Andrew from
AJP Construction and Damian from Cantilever, met on site to discuss the first
floor extension designed by Sago Design. A few
weeks later they had another meeting to discuss the proposed build and review
the preliminary structural sketches. It
was at this meeting where Andrew mentioned the option of changing the timber
stick framing to CLT. A
few months later the three met with Sean from XLam. Sean had prepared a preliminary CLT panel
layout and Andrew had compared the price.
It was decided that the project would proceed with the CLT option.
Cantilever was engaged to take full responsibility for the structural
engineering package including the engineering, documentation and the certification. The
structural engineering certification was simplified by the substantial help from
AJP Constructions, Sago Design, XLam and Rothoblaas.
Over the past 25 years, Cantilever has been involved in mass timber
buildings, including the use of large glulam beams and floors and CLT. All of this experience assisted with
streamlining the process.
The advantages of using CLT are obvious; from a cost
perspective, a setout perspective, a safety perspective and a
sustainability perspective. It is also
one of the few sustainability initiatives that has obvious and real cost
savings. Cantilever has identified CLT
as being the future of building and has set up a specialised CLT team, CantileverCLT
dedicated to the structural
engineering of CLT building. We predict
more than 30 builds using CLT and Mass Timber in 2019 from the CantileverCLT
Structural Engineer: Cantilever Consulting Engineers