Standard Timber Stair Tread Sizes in Australia
Most Australian hardware suppliers stock treads in a small set of standard dimensions. Knowing them saves you waste and lead time.
- Thickness: 32 mm, 38 mm or 45 mm (heavier for external use).
- Width (going): 240 mm, 270 mm, 290 mm and 355 mm are common.
- Length: typically 900 mm, 1050 mm, 1200 mm or 1500 mm — match your stair width.
- Nosing profile: bullnose, square-edge or pencil-round.
What the National Construction Code Requires
Domestic Class 1 stairs must comply with the National Construction Code (NCC), which references AS 1657 for industrial stairs and Volume Two for housing. The numbers below are the workable envelope for most Brisbane stairs.
- Tread depth (going): 240–355 mm.
- Riser height: 115–190 mm.
- Nosing overhang: up to 25 mm.
- Consistency: every riser must be within ±5 mm of every other.
- Slip resistance: P4 classification required for external treads in wet areas.
Which Timber Species Should You Choose?
Tread material choice depends on whether the stair is internal or external, and how much maintenance you're willing to commit to.
Spotted Gum
Class 1 durability, dense, beautiful colour variation. The default for premium external stairs in South-East Queensland.
Blackbutt
Slightly lighter colour than spotted gum, equally durable, more uniform grain. Often preferred for modern architectural builds.
Victorian Ash
Pale, even grain. Excellent for internal stairs and clear-finished interior treads. Not recommended for outdoors without a roof above.
Treated Pine
Budget option for painted treads. Watch for soft spots after a few years of foot traffic; replace treads as a maintenance item.
How Many Treads Will You Need?
Quick rule of thumb: total stair height (rise) ÷ comfortable riser height (about 170 mm) = number of risers. The number of treads is always one less than risers because the top landing acts as a tread.
For a typical 2700 mm Queenslander floor-to-ground rise, that's 16 risers and 15 treads. Always add 1–2 spare treads to the order for waste and future repairs.
How Tread Choice Affects the Cost of Your Stair
Tread material is one of the biggest levers on the overall cost of a stair. From most economical to most expensive, the common Brisbane options run roughly in this order:
- Treated pine 38 × 290 mm — the most economical structural tread; paints well, softer underfoot.
- Victorian ash 32 × 290 mm — a step up in appearance, better suited to covered stairs.
- Spotted gum 38 × 290 mm — a premium exterior hardwood with excellent durability and slip performance.
- Recycled hardwood (heritage match) — the most expensive option, used where a period profile must be matched.
Need Help Sourcing and Installing Treads?
We supply, dress and install timber stair treads across Brisbane, Moreton Bay and the Sunshine Coast. See our full external stairs service or request a quote — bring your stringer dimensions and we'll suggest a species and profile to match the rest of the home.
Need a Hand From a Brisbane & Sunshine Coast Carpenter?
Carpentry Worx is QBCC licenced and servicing Brisbane North, Moreton Bay and the Sunshine Coast. Get a quote on your project today.
Useful Links
Related Articles
- External StairsQueenslander Stairs Restoration: A Brisbane Owner's GuideOriginal Queenslander stairs are gorgeous — and often quietly rotting. Here's how to restore them safely, sympathetically and to current code.Read article
- External StairsOutdoor Timber Stairs: The Brisbane Material GuideWhich timber survives Brisbane's hot, wet, humid climate — and which one falls apart in five years? A working carpenter's honest comparison.Read article
- External StairsWhat Determines the Cost of External Stairs in Brisbane?A working carpenter's guide to what drives external stair costs in Brisbane — the specification choices that matter, where you can save, and what a fair quote looks like.Read article
- External StairsStair Balustrade Regulations in Queensland — Plain EnglishConfused by 865 mm, 1000 mm and 125 mm? Here's exactly what the National Construction Code requires for stair balustrades in Queensland — and where homeowners trip up.Read article