To ensure that the structure of any construction performs to the expected dead and live loads to which the building will be subjected to over the course of its life, it is necessary to choose the size, length and grade of timber according to the expected loads and overall function. To determine the spanning ability of load carrying members, span tables allow users to choose an appropriate size and stress grade to achieve spanning needs.
Each timber species, and manufactured product performs differently and it is important to obtain the most up- to-date span tables from the manufacturer and or supplier.
Even recycled timber needs to meet the required performance criteria for which specific span tables have been created. An interim standard for recycled timber products has been created to ensure compliance with the necessary construction requirements across Australia. Two interim standards have been completed for recycled products, the Interim Standard - Decorative Products and the Interim Standard - Structural Products. The standards provide the guidelines for users as to performance standards for recycled timber products.
Stress grades and timber sizes combine to determine the spanning ability of load carrying members. Span tables allow users to choose an appropriate size and stress grade to achieve spanning needs. For simple construction, such as domestic construction, this can be determined from span table supplements in AS 1684.2 and AS 1684.3.
For multi-unit residential construction software the Timber Solutions software has the capability to be changed to undertake design for these buildings.
The various manufacturers and providers of structural product have proprietary software to assist with the calculation of the spanning ability of their products. Visit the Software & Design Resources section for a list of some of the software available, together with further resources for timber design.
Related Links:
Interim Standard - Structural Products
Interim Standard - Recycled Decorative Products