What You Need to Know About Australian Regulations for Treads

A riser (R) shall be not less than 130 mm and not greater than 190 mm.

The going (G) shall be not less than 240 mm and not greater than 355 mm.

The going shall be not greater than the tread depth (TD) plus minimum 10mm overlap between the rear edge of one tread and the nosing of the tread above.

As stated under the general provision of constructing stairs, a staircase must have no less than two risers and no more than 18 without a 750 mm2 landing area.

When creating a long staircase, it must have no more than 36 risers without directional changes.

Following this, each tread and riser has to be the same measurement within a single flight.

All risers and all goings in the same flight of stairs shall be of uniform dimensions within a tolerance of ±5 mm.

Riser openings for an Open Rise staircase shall not have a 125 mm sphere passing through.  Hence, the tread must have a dummy riser to reduce the gap between risers.

When constructing the flight of stairs, these must not have over three winders in a quarter-landing section. If the staircase is a half-landing section, these must not have more than six winders.

Should there be a door that opens onto a staircase, there must also be a landing in front of it before the drop of the stairs— unless the floor to floor dimension is less than 570 mm. This will then only require a zero tread instead of a landing.