There has been a positive step forward in the tall timber building movement with proposed changes to the National Construction Code (NCC) Volume 1 to allow timber construction in buildings up to eight storeys for apartments, hotels and offices.

The Forest and Wood Products Australia Limited (FWPA) has led the march toward industry change. The organisation has consulted with representatives from timber, building and insurance industries and met with regulatory bodies - in particular fire authorities - to develop the Proposal for Change to the National Construction Code Volume 1.

FWPA has presented a Proposal for Change to the National Construction Code for the use of timber framing for certain types of buildings. The proposal includes lightweight timber framing and massive timber systems in conjunction with the use of appropriate layers of fire resistant plasterboard and sprinklers.

The proposed changes would create a deemed-to-satisfy (DTS) solution for Class 2 (apartments), Class 3 (hotels) and Class 5 (office) buildings up to eight storeys, or the equivalent of 25 meters.

The current NCC DTS solution restricts timber building systems to three storeys. Tall buildings would require an alternative solution which would include a fire engineered approach for approval. According to the NCC, “An Alternative Solution means a Building Solution which complies with the Performance Requirements other than by reason of satisfying the Deemed-to-Satisfy Provisions.”

Timber construction height limits depend on the building classification and type of construction. The NCC currently limits most Type C construction to a single storey (Class 5 and Class 6 can rise two storeys).

Countries such as the UK, Sweden, Spain, Netherlands, New Zealand and Norway allow under a DTS solution a maximum of 20 storeys for tall timber buildings. The US and Canada have made a move to increase heights under DTS requirements to six storeys. However, Australia has yet to make any significant changes until now.

In addition to the proposed changes to the NCC,  The Timber Development Association together with the FWPA have developed the Commercial Building Costing Case Studies: Traditional Design vs Timber.

The research case study compares the cost of building in engineered timber and of building with steel and conventional concrete materials. Four types of commercial building were compared: apartments, offices, portal frame structures and house-size aged-care buildings. The final report can be found on the FWPA website.

The report discovered that in all cases, building with timber lowered construction costs. In the examples used, cost savings were 2.2 per cent for an eight-storey apartment building, 9.4 per cent for a single storey industrial shed, 12.4 per cent for a seven-storey office building and 13.9 per cent for a two-storey aged care facility.

Changes to the NCC together with the research that the FWPA has completed are all positive steps towards a vibrant and commercial viable engineered timber industry.

  • It would be interesting to see whether those cost savings resulted more from the actual materials used or the assembly times due to prefabrication etc.

    It is good to see the idea of more use of timber on high rises. Provided the fire issues can be overcome, it would be wonderful to more wood used in apartment buildings and offices.

    • Hi John,

      The cost savings in timber structures are largely in the speed of construction and reduced time on site. This is largely due to the prefabricated nature of the products and the simple construction allowing fit-out trades to follow on sooner and finish quicker.

      There have been studies done on the costs which corroborate our own research at AECOM into this subject.

      The real problem is convincing builders and QS's to price these time savings accordingly!

      As for fire it's soon going to be possible to build up to 8 storeys under the updated NCC for 2016. These buildings are made of very large and solid pieces of timber which do not readily ignite and if they do they char slowly which insulates the timber beneath and can provide significant strength after a long period of fire.

  • While I have no doubt that timber is a very useful building product and – on the face of it – a 'renewable resource', the latter consideration is dependent upon the maintenance of sustainable supplies of the required types of plantation timber without the demand for such sustainable plantation growth being at the expense of existing natural forests or agricultural land. Given that much of the timber used for buildings is now in the form of 'engineered' timber I wonder if bamboo may be a practical source?.