New research has demonstrated medium density fibreboard (MDF) is suitable for use in more elements of stair construction than previously thought. The study has resulted in the development of new industry guidelines around the appropriate use of MDF products in stair structures across a range of scenarios.
Understanding the characteristic properties of any material is important when making design considerations and predicting compliance, as is thorough knowledge of its parameters and limitations.
A FWPA-supported project, Strength verification of MDF products and fitness for purpose in structural applications, aimed to fill the knowledge gaps around the characteristic properties of MDF for structural design and application. The team of researchers from the Engineered Wood Products Association of Australia and the University of the Sunshine Coast conducted a thorough review of stair construction practices through engagement with manufacturing and construction businesses in south east Queensland.
They found that, while the use of MDF is common practice in stair construction for dry and protected environments, it is typically limited to treads (the part of the step which is trodden on) and risers (the near-vertical element that forms the space between one step and the next). It is only used for stringers (the housing on either side of a flight of stairs) that can be directly fixed to wall studs or supported by a wall frame, due to concerns over its load-bearing capabilities. Stringers for free-standing stairs are therefore more commonly constructed from pine or hardwood.
A literature review identified that current basic design methods significantly overestimate the loads carried by the stringers in any staircase. Mechanical testing was used to verify the structural behaviour of MDF staircases and stair elements. This testing allowed for the development of the guidelines, which confirm that 32mm-thick MDF is a suitable material for the stringers of free spanning stair structures up to 2.3 meters in height.
The results of this testing were also used to develop comprehensive guidelines specifying suitable MDF products and configurations for treads and risers.
The team will now look at opportunities for market education around the capacity of structural MDF products in stair construction, with a view to growing the market through increased confidence, acceptance and adoption.
The researchers also hope to conduct further studies to discover the measures required to extend the use of MDF to other structural applications.
The full report is available on the FWPA website.