Smart engineered wood building
May 10, 2018
Tilling SmartStruct is on a winner for engineered wood with its Tecbeam product chosen to build a landmark affordable housing project in Melbourne.
The unique construction design will be a program feature at the Frame 2018 Timber Offsite Construction conference and exhibition at Park Hyatt Melbourne on June 18-19.
The Department of Health and Human Services (DHHS) project designed by Billard Leece Partnership – 68 apartments in two buildings of three and four storeys in Stoke St in the suburb of Preston – is located on two relatively tight sites with existing houses to the side and back.
“Due to the building site’s constraints, the engineer Irwinconsult specified Tecbeam floor system for the job,” said Tilling’s commercial co-ordinator, Chris Wookey.
Over two sites, site 1 is a three-storey building with 22 dwellings, while site 4 is a four-storey building containing 46 dwellings.
The construction comprises a combination of lightweight timber frames with steel portal frame, timber and hybrid structural beams. The innovative feature is Tecbeam engineered timber joists supporting MaxiFloor flooring and timber stud walls.
With DHSS’s emphasis on sustainability, the engineered timber floor system was a massive plus. “It could have been built with form concrete, but that would have involved extra time and costs” Mr Wookey said.
“With timber, the building becomes more carbon-neutral – the more timber you can lock into a building, the better the carbon rating. Timber is also light-weight and performs better for the environment than other heavy steel and concrete building products.”
Tecbeam is an engineered wood floor joist system with a pre-formed steel web and LVL flanges top and bottom. In multi residential construction, it brings a lot of advantages due to its inherent high stiffness.
“It can span very long distances without any internal load-bearing walls underneath. It’s stiffness also means it has a very good dynamic response, giving excellent acoustic results once the job is finished,” Mr Wookey said. LVL blocking can also be added to increase stiffness even further.
Because Tecbeam has large holes within the steel web every 600 millimetres, all services such as plumbing and air-conditioning can be installed into the floor cavity without having to drill additional openings.
“You have to be able to get ducted services from the kitchen or bathroom extraction to the balcony, without the need for bulkheads or dropped ceilings.” Mr Wookey said.
The Tilling design office details the floor system so “we have one continuous void from the front to the back of building. Depending on whether there is structural steel in the way, we may set up dropper locations. We can drop the services into the holes and run them out to the balcony. Ease of services installation is one of the key reasons why the Tecbeam product was chosen.”
Other advantages include the capacity of Tecbeam to span just over 7.2 metres. The floor –MaxiFloor aerated concrete floor system that sits on top – is significantly heavier than particleboard or other board floors.
“Tecbeam design loads come into play, as it can carry the additional weight,” Mr Wookey said. “A conventional joist could not get anywhere near that loading, so we can use lightweight Tecbeam to deliver a floor that has the structural performance of formed concrete.”
Tilling manufactures Tecbeam under licence – the only company to do so in Australia – but it’s comprehensive technical advisory and engineering detailing service brings significant benefits to the builder, as became obvious in the design process.
As part of their structural due diligence, the Tilling team did a full review of how the wall frames were proposed for construction by the builder.
Tilling recommended that they opt for modifications; changing from 300mm spaced pine studs to 450mm spaced LVL studs. “Any wall frames with 300mm centres, means you can’t get the nail gun in to ‘nog’ the wall after you’ve built it; 450mm centres can be built on site more efficiently using standard nail gun procedures,” Mr Wookey said.
With light-weight building over four storeys in height, the load-bearing through the LVL studs was considerably lowered, enabling the builder, S.J.Higgins to reduce ground floor walls from 120mm to 90mm, thus saving in both timber and cost.
All up, the Stokes St engineered timber structure - both sites - will contain close to 20,000 lineal metres of Tecbeam joist sections when complete.
The roof structure also presented design challenges to Tilling.
Their solution was to convert the roof structure from traditional trusses to Tecbeam, enabling the inclusion of additional loads for air-conditioning and solar panels, at the same time ensuring the roof falls were within height limitations required by planning constraints on site.
The buildings’ Class 2 fire regulation means floors must have a 90-minute fire rating. Each element in the building, from apartment to ceiling/floor spaces, must have this rating. Required fire compartmentalisation means “you are not allowed to have potential fire transfer between walls or floors,” Mr Wookey said.
“The Tecbeam, MaxiFloor and fire-rated plasterboard underneath combine to comply with a 90/90/90 fire rating.”
Mr Wookey has no doubts about the benefits of Tecbeam on the project. “It’s faster and easier to put together on site,” he said.
Tilling SmartStruct is Principal Partner for the Frame 2018 event titled ‘Timber Offsite Construction’ and will feature their engineered timber solutions in an extensive product display. Also, the DHHS project will be discussed in a panel session with all the main project participants.
Frame 2018 will be held on Monday and Tuesday 18-19 June at Park Hyatt Melbourne, and for details visit the website www.frameaustralia.com