How high does a balustrade need to be on a deck or balcony, and when is one required at all?

A continuous barrier is required along the side of any trafficable surface, including a deck, balcony, verandah or landing, wherever it is possible to fall 1 m or more to the surface beneath. [1]

Where a barrier is required, it must be built to these minimum heights: [2]

• 1 m above the floor of a deck, balcony, verandah, landing, corridor or similar general-access surface;
• 865 mm above the nosings of stair treads or the floor of a ramp;
• a transition zone is permitted where the 865 mm stair barrier meets the 1 m landing barrier.

Openings in the barrier, including decorative infill, must not let a 125 mm sphere pass through, and any gap between the barrier and the edge of the trafficable surface must not exceed 40 mm. Where the potential fall is more than 4 m, horizontal elements between 150 mm and 760 mm above the floor must not facilitate climbing. [2]

These requirements are identical in NCC 2022 and NCC 2025, so in WA, where either edition may currently be elected for a permit application, the barrier design is the same whichever edition the project nominates. [2]