Balustrades often appear straightforward in design, yet they are among the elements most closely reviewed during site inspections.
This article brings together the key dimensions and checks most commonly referenced on site, helping builders and designers develop a clear and practical understanding of balustrade requirements early in the planning stage.

When is a balustrade generally required?

In residential projects, a balustrade is generally required where it is possible to fall 1.0 metre or more from a trafficable surface to the surface below.

This measurement is taken vertically from the walking surface to the level beneath, and is one of the first checks typically made on site.

Balustrade height: the two numbers most sites check

For most residential inspections, attention is usually focused on two minimum balustrade heights:

• ·Stairs and ramps: not less than 865 mm, measured above the stair nosings or ramp surface

• ·Landings, balconies, decks and other level edges: not less than 1.0 metre, measured above the finished floor level

These two figures cover the majority of common residential situations and are widely referenced during site checks.

Child-safety gaps: the “100 mm sphere” rule

Openings within a balustrade must be small enough that they do not permit a 125 mm sphere to pass through.

This applies not only to the spacing between vertical elements, but also to any openings created by panels, decorative features, posts or fixings.

On stairways, openings are assessed above the nosing line, which is why stair sections often receive closer scrutiny than flat landings.

Common balustrade issues seen on site

In practice, some balustrade issues appear repeatedly during inspections, including:

• ·Heights that appear compliant on drawings but change after finishes are installed

• ·Stair openings that meet requirements on landings but fail along the stair flight

• ·Edge gaps introduced by side-fix brackets or posts

Identifying these details early can help reduce rework and inspection delays.

Important notice

This article provides general guidance only. Final compliance must be confirmed against the applicable NCC edition and the advice of your project certifier.