Generally, attention surrounding compliance of staircases focus on the design dimensions (i.e. the rise and going of the steps). Meanwhile, from a structural perspective, most often it is assumed that staircases are manufactured and supplied to meet the appropriate structural requirements of the National Construction Code (NCC). However, with a wide range of low cost materials and substitute products on the market being used for a variety of elements in a building project, the risk is that these non-structural materials may ‘slip through’ and find their way into staircases being constructed on your project. 

Such materials that may not be structurally rated may include; non-structural grades of timber, non-structural plywood, and non-structural medium density fibreboard (MDF). Therefore, just as you would ensure that you have appropriate material selection and engineering for a frame member such as a lintel, the staircase stringers and treads which take the load of a person walking up and down the staircase also require appropriate selection and structural engineering. Easy solutions are available. 

When using timber for staircase construction, one can apply tread and stringer thickness dimensions based on the stress grading rating of the timber (i.e. F8, F17, etc.) for the required span and intended use approved by an engineer. Therefore, because timber has a structural rating to start with, timber is an obvious cost effective choice for meeting the structural compliance requirement. Other materials such as steel, reinforced concrete, structural ply or structural LVL are also potentially suitable material choices for structural compliance.

There is an issue when using a material like MDF for staircase construction. As confirmed by the relevant certification body, the Engineered Wood Products Association of Australasia (EWPAA), as at February 2014 there is “no HP (high performance) MDF boards made by Australian manufacturers certified to AS/NZS 1859.2 suitable for stair treads and stringers.” This makes the choice of using MDF problematic given it does not have the base level structural certification required (as per AS/NZ 1859.2) to begin with. The only way that standard, non-loadbearing MDF could be then used for staircase construction and still comply, is if the complete staircase construction was to have additional appropriate structural reinforcement applied to the MDF and/or engineering approval.

Therefore to avoid the risk of structural non-compliance on your project, ask the manufacturer for the appropriate structural engineering certification at the time of procuring the staircase for your project or as part of the building permit process. As the last thing a responsible building practitioner wants is to be left carrying the risk and liability of a structurally non-compliant staircase that may fail or not stand the test of time.

More detail on this issue and the structural compliance of staircases is covered in the April/May 2014 edition of Master Builder Magazine (p.p. 59 to 63).

Alternatively, for more information please contact Master Builders Building Services on (03) 9411 4555.