Bookmark and share on Twitter, Facebook, email, etc

Stair Safety Overview - Size of risers and treads

Want to know more about the importance of having the same dimensions for each tread in the same flight of stairs? Read more now!
Dimensional irregularity is a common cause of missteps and falls on stairs. The BCA calls for the dimensions of goings and risers of a stair to be constant throughout each stair flight. That is, all risers and goings in the same flight of stairs should have the same dimensions.


Comfort and safety on stairs are affected by the height of risers. It has been demonstrated that stair preference is more sensitive to changes in stair risers than to changes in goings. In general, high risers are regarded to pose increased risk as they demand more physical exertion, particularly of frail older people. However, risers that are too low are also hazardous as they cause the foot coming off of it to land further back on the tread. A low riser will place the foot back so far that when the opposite foot attempts to clear the surface below, the heel will become caught on the tread surface. Therefore, AS 4226 stipulates not only the upper but also the lower limits of the riser heights; riser heights should be uniform in the range between 150 mm and 180 mm (Standards Australia, 2008). However, for elderly people or people with ambulatory problems, a rise of 95-105 mm is recommended (CSIRO, 2001).  A 125mm sphere should not pass through the gaps between treads.

Steps should be large enough to provide adequate footing. Short tread steps can make people stumble or fall as people might place a foot far forward the tread in descending. Stair treads should be level and able to accommodate the full length of an average adult’s shoe (Standards Australia, 2008). However, too large a tread is not recommended as it is expensive and inefficient in terms of the space it occupies. Treads of 300 mm allow safe placement of a four-point walking stick, and treads of 575-600 mm are recommended by the CSIRO for people using walking frames.


Jung, Y. M. & Bridge, C. (2009). Stairs - Summary bulletin. Sydney: Home Modification Information Clearinghouse, University of New South Wales. November 2009 [online]. Available from

Published on: 03-Aug-2010. Topic/s: Stair safety, compliance, and regulations