Timber Frame Structures in Multi-Storey Projects 2

By
Wednesday, April 8th, 2015
liked this article
Embed
Siemens – 300×250 (Expires October 31st 2017)
advertisement
install
FavoriteLoadingsave article

There are a few key elements in the development and design process that underpin successful outcomes for timber projects in the commercial construction industry.

Why a timber frame?

You’ve doubtless read the recent industry assertions that a timber-framed build can be cheaper than concrete. This can be the case, but as in much of construction, the devil is in the detail. The new buzzword is ‘hybrid’ construction – the use of both in-situ and prefabricated structural elements. Originally applied to the advent of pre-cast concrete panels, hybrid timber construction is now commercially feasible using floor cassettes and prefabricated wall frames. The accuracy, speed and high-quality finish of factory made components can be combined with the economy and flexibility of timber and of timber trades.

In well-publicised results for their 2014 timber-framed The Green Project, Australand has asserted potential savings of 25 per cent on the structural frame when taking into account materials and labour, time and preliminaries. This massive result can’t just be taken at face value, however. In order to realise those savings, Australand created an end-to-end supply chain management discipline that is timber-centric and that extracts maximum benefits from the market opportunities that timber offers.

Design Considerations

Effective delivery of hybrid timber procurement requires a ‘structure first’ approach. The following flow process indicates the step change from design for standard construction:

Click to enlarge

Click to enlarge

In countries where timber multi-storey procurement is well established, numerous studies reinforce the need for development and design management to consider the supply chain and importantly, to enlist fabricator input early. Their involvement will aid efficient overall sequencing and programming and ensure that when the time comes for materials selection, detailed design and shop drawings, that unnecessary delays due to redesign are minimised.

The estimating manager for Australand, Kase Jong, stresses the importance of partnering with key consultants and suppliers who share the same vision for the design and construction brief. This brings me to the question of what a developer can realistically expect from local suppliers.

Supply

The timber supply industry in Australia has historically developed to service the domestic housing construction industry. Over the past 20 years, the commercialisation and increased market penetration of new products such as gang nail trusses, LVL and I-Joists has also driven the development of engineering software tools designed for use by the estimators and detailers at truss and frame suppliers.

Whilst these tools enable users to undertake simple load path and member size analysis, they are not geared or certified for the complex engineering required in a multi-storey product.

Likewise, the standard details that may apply to a domestic jack truss or typical floor frame are a far cry from the detail required for multi-storey shop drawings that integrate service runs, set downs and – for cassette systems – crane lifting points.

There are, however, national suppliers such as Tilling Timber, with the in-house engineering capability and technical documentation capacity to meet the most exacting requirements of a major developer such as Australand.

Having been in the position on one of my own developments where after tender, the cost savings required to achieve project viability led me to change from concrete frame to a timber load bearing structure, I know the hassle that can be involved when one’s consultants are unfamiliar or unwilling to look for an elegant timber structural solution.

Firms unfamiliar with the capabilities of timber products can erode potential savings with undue conservatism and waste valuable time if they are unwilling to work cooperatively with suppliers. However, there are now selected engineers, building surveyors and fire engineers that have the experience and knowledge to deliver great timber design outcomes.

Selection is key.

Embed
FavoriteLoadingsave article

Comments

 characters available
*Please refer to our comment policy before submitting
Discussions
2
  1. David Bowers

    Having been a frame and truss detailer in NZ and now doing the same in the UK. I would recommend the UK as a good source of knowledge for large scale timber buildings. The majority of my work is for apartment blocks ranging from 3 to 6 storeys as well as multi storey schools circa 7000m2.
    To reduce time scales on site prefabrication is essential with Pre breather papered walls, floor cassettes and sometimes truss cassettes the norm.
    Large scale timber sites can however cause a significant fire risk at the construction stage, prior to plasterboard being fitted. The STA (structural Timber association has produce several guidance documents for fire mitigation measures during construction, following some spectacularly large fires. h

  2. Paul Edwards

    Can't agree entirely with the proposed change in methodology. If you start by choosing to build with Lego, you get a Lego building. Surely the best option is to keep an open brief and let the market propose different and competitive construction methodologies.