The building approval exemption
Under the Building Regulation 2021, Schedule 1, building work for a retaining wall is accepted development (no building approval) only if all of these are true:
- there's no surcharge loading over the wall's zone of influence;
- the total height of the wall and the fill or cut it retains is no more than 1 m;
- the wall is no closer than 1.5 m to a building or another retaining wall; and
- it doesn't form part of the fencing for a regulated pool.
Brisbane City Council lists the same conditions on its retaining wall page. Exempt walls still have to be built properly and comply with the building codes.
When planning approval can apply
Council generally doesn't require planning approval for a wall supporting less than 1 m of fill or excavation. It may be needed where the site is covered by an overlay such as flood, landslide, waterway corridor, biodiversity, bushfire, heritage or acid sulfate soils; where the wall is associated with a house on a small lot, a subdivision or a material change of use; where filling or excavation exceeds the thresholds in the Filling and excavation code; or in a neighbourhood plan area. Check your address in City Plan online mapping.
What this means in the south-west suburbs
- Centenary hillside lots (Jamboree Heights, Middle Park): narrow side paths and close terraces often break the 1.5 m rule.
- Riverside streets (Mount Ommaney, Sinnamon Park): flood and waterway overlays can bring in planning approval.
- Compact and infill lots (Richlands, Darra): small-lot and subdivision rules, and walls close to houses.
Quick check
Over 1 m? Driveway, pool, shed or house above? Within 1.5 m of a building or another wall? Part of a pool fence? In a flood or other overlay? If any answer is yes, expect an engineer, a certifier, or both.
Common questions
What is surcharge loading?
A load on the soil behind a wall that can consolidate it, such as a driveway slab, building, shed, pool or extra fill. Loads only from people or vehicles moving over the ground, or rain, don't count.
Who approves a retaining wall that isn't exempt?
A private building certifier gives building approval, usually based on an RPEQ engineer's design. If planning approval is also needed, a development application goes to Brisbane City Council.
Is a retaining wall the same as a fence?
No. Brisbane City Council treats them differently. A fence on top of a wall adds wind load and combined height, so design them together.
Want a price for your wall?
Send the suburb, a rough length and height, and what the wall holds up. A licensed builder can then contact you to arrange a quote.