Need a flight built or replaced rather than explained? We build external stairs in Brisbane: measured, set out to code and quoted by Ben.
Sloping blocks are common in Brisbane, and a slope can leave a back door, a deck or the lower yard awkward to reach. Outdoor stairs fix that, provided they are set out to the slope and built for the rain. This guide walks through how it is done.
Start with the slope, not the stairs
Two measurements decide everything: the total rise, which is the vertical height between the top and bottom of the stairs, and the run, which is the horizontal distance available. On a slope the ground falls away under the flight, so measure the rise to the point where the bottom tread will land.
Those numbers are then fitted to the National Construction Code limits for house stairs: risers between 115 mm and 190 mm, goings between 240 mm and 355 mm, and twice the riser plus the going between 550 mm and 700 mm. Our guide to building external timber stairs has the full list and a worked example. The stair calculator fits any rise to those limits.
Step-by-step outdoor stair construction on a slope
1. Choose the line
A straight flight is the simplest where the run allows it. A flight can have no more than 18 risers, so a long drop is broken with landings, each at least 750 mm long. On a steep block the stairs can turn at a landing and double back, which shortens the footprint and gives people a place to pause.
2. Set out the flights and landings
Divide the total rise into equal risers. Every step in a flight has to match its neighbour within 5 mm, and that matters most on a slope, where uneven ground tempts people to adjust the steps as they go. The steps stay equal and the footings take up the difference.
3. Dig and pour the footings
Each landing and the foot of each flight sits on concrete footings taken down to firm ground. Timber posts are held above the concrete on steel stirrups, or are treated to H5 if they are set in the ground.
4. Plan the drainage
Brisbane's summer storms send a lot of water down a slope quickly, and it will run along and under the stairs. Shape the ground under the flight so water passes through, leave gaps between treads so they shed water, and never let soil or mulch build up against the stringers.
5. Build the flights
Stringers are cut to the set-out and fixed to the landings, then the treads go on with corrosion-resistant fixings. Treads open to the weather need a wet slip rating of P4 or R11 under the code.
6. Add handrails and balustrades
A flight that rises 1 m or more needs a handrail at least 865 mm above the tread nosings. Anywhere a person could fall 1 m or more, which is common beside stairs on a slope, a balustrade is required: at least 1 m high on landings, with no gap a 125 mm sphere can pass through. The detail is in Part 11.3 of the National Construction Code housing provisions.
Timber stairs or steps formed in the ground?
There are two broad ways down a slope. Timber stairs span the fall on stringers and landings and touch the ground only at their footings, which suits steep drops and the run from a deck to the yard. Steps formed in the ground, in concrete, stone or sleepers, suit gentle slopes and garden paths. Bernard Building is a carpentry crew, so the stairs we build are the timber kind.
Timber that lasts on a Brisbane slope
Stairs on a slope sit closer to wet ground than a flight off a verandah, so durability matters more. Class 1 hardwoods such as spotted gum and ironbark are rated very durable. Treated pine is graded by hazard level: H3 above the ground, H4 close to it and H5 in it. Hot-dip galvanised or stainless steel fixings are the norm outdoors. WoodSolutions publishes the natural durability ratings for each species.
Do outdoor stairs on a slope need approval?
Building approval in Queensland comes from a building certifier. Repairs that leave structural components alone do not need it, but a new set of stairs should be checked with a certifier before work starts. Brisbane City Council's guidance on decks and decking approvals covers the planning side, which matters for homes in the Traditional building character overlay. Our approval guide for decks and stairs goes through it job by job.
Mistakes that shorten the life of outdoor stairs
- Timber resting on soil instead of footings
- Risers adjusted to suit the ground, leaving uneven steps
- No path for stormwater, so the ground under the flight washes out
- Indoor-grade fixings that rust
- No landing on a long flight
- No balustrade beside a drop of 1 m or more
Stairs for a sloping block in Brisbane
Bernard Building builds external timber stairs across Brisbane, including the hillside suburbs around The Gap, Bardon, Paddington and Red Hill. Ben Bernard walks the block, measures the fall and quotes the job himself. See our external stairs service or get a quote.
More guides from the tools
- Timber Stairs Brisbane: External Timber Stairs Guide
- External Stairs Brisbane Designs Trending in 2026
- How to Build External Timber Stairs in Australia: Guide
Planning the job itself? Start with our external stairs service page.