Stairs and Balustrades in Two Storey Homes

The internal stair is the one part of a two storey home everyone uses every day, and it is a common place for falls. The building code sets firm dimensions for stairs, landings, handrails and balustrades. Getting them right on the drawings is far easier than fixing them after the stair is built.

Which rules apply

Houses in NSW are currently built to NCC 2022, using the ABCB Housing Provisions. Part 11.2 covers stairs and ramps, and Part 11.3 covers barriers and handrails. NSW moves to NCC 2025 from 1 May 2027, so check which edition applies when your approval is issued. The figures below are from the 2022 edition of the Housing Provisions.

Stair geometry

The riser is the height of each step and the going is the horizontal depth of each tread. For a standard straight stair:

each riser must be between 115 mm and 190 mm
each going must be between 240 mm and 355 mm
twice the riser plus the going must fall between 550 mm and 700 mm
a flight must have at least 2 and no more than 18 risers
risers and goings must be consistent, with no more than 5 mm difference between neighbouring steps and 10 mm across a flight

That last point catches many builds. If the finished floor level upstairs changes after the stair is made, for example from thicker flooring, the top or bottom step can end up out of tolerance.

Open risers are allowed, but the gap between treads must not let a 125 mm sphere pass through. Winders (tapered steps that turn a corner) can replace a landing, but the code limits them to three in a row for a quarter turn and six for a half turn. Tread surfaces and nosings must meet slip resistance ratings.

Landings

Landings must be at least 750 mm long. Where a door opens onto a drop of more than three risers or 570 mm, a landing is needed at the doorway. Landings must run across the full width of the doorway they serve.

Handrails and balustrades

A handrail is what you hold, while a balustrade (the code calls it a barrier) is what stops you falling off the side.

A barrier is needed anywhere a person could drop 1 m or more. That includes stairs, landings, voids, balconies and decks.
Barrier height must be at least 865 mm above the stair nosings, and at least 1 m on landings, corridors and balconies.
No gap in a barrier may be big enough for a 125 mm sphere.
If the drop exceeds 4 m, horizontal parts between 150 mm and 760 mm above the floor must not make the barrier climbable. A void over a double-height entry can easily reach this height.
A handrail is needed on at least one side of each flight, at least 865 mm above the nosings, and it must be continuous along the flight.

Wire balustrades must follow specific tension and spacing rules, and every barrier must also be strong enough for the loads the code requires.

Common defects we see

balustrade gaps over 125 mm, often at the bottom rail or beside a newel post
a landing barrier built to 865 mm where 1 m is needed
horizontal battens or rails on a void balustrade where the fall is over 4 m
uneven risers at the top or bottom step after floor finishes go down
handrails that stop short or are broken by brackets
glass balustrades without documents showing the glass and fixings comply

When it gets checked

Stairs are usually finished late in the build, so most of these items are checked at the final inspection, which comes before the occupation certificate. Ask your stair maker for shop drawings early and have the certifier review them against the approved plans. A plan assessment can pick up stair problems before construction. The same barrier rules apply to raised outdoor areas, covered in our decks, pergolas and patios service.

Building two levels or adding a first floor? See our double storey homes service, or book an inspection at least 48 hours ahead.

Local help across NSW

CertifiBuild certifies Class 1 and Class 10 work in 39 council areas. Local rules on these council pages are a good place to start: Hornsby Shire Council, Wingecarribee Shire Council, Blacktown City Council, Inner West Council, Northern Beaches Council, Lithgow City Council.

Suburb pages with local planning notes: Exeter, Guildford West, Huntleys Point, Kings Langley, Leichhardt, Newport, Northwood, Portland, Wahroonga, Yowie Bay. You can also browse every service area.

Stairs and balustrades in a double storey home: getting them right