Short answer
A 10 m long, 0.8 m high treated pine sleeper wall has 8 m² of face and costs about $1,600 to $3,600 installed. Building it yourself takes 21 sleepers (4 courses of 5), 6 steel posts about 1.6 m long, 0.76 m³ of footing concrete and 2.6 m³ of drainage gravel, which comes to roughly $1,340 to $1,827 in materials. Cost per square metre rises with height, and walls over 1 m (or any wall carrying a driveway or building) need an engineer.
Use this free retaining wall cost calculator to estimate the installed price of a wall by length, height and material, with a materials list for sleeper walls and a warning when your wall is likely to need approval or an engineer.
Retaining wall cost calculator
Wall prices are indicative ranges from published Australian guides, which come mostly from contractors and lead-generation sites and vary widely. Walls over about 1 m, or with any load above them, need an engineer. Ranges reviewed October 2026.
How we calculate the cost
- Face area: length x height in metres. A 10 m wall at 0.8 m high is 8 m².
- Installed price, up to 1 m: face area x a price range per m² for the wall type. Walls under 0.5 m use a minimum of $100 to $250 per metre, because small walls cost more per square metre.
- Installed price, over 1 m: length x a price per metre by height band, because costs rise faster than the area does. Per-m² rates from a 1 m wall should not be applied to a taller wall.
- Sleeper walls: courses = height ÷ 200 mm, rounded up; sleepers per course = length ÷ sleeper length, rounded up; plus 5% spare.
- Posts: steel posts about twice the wall height long (a 1 m wall takes a 2 m post), set in 450 mm holes about as deep as the wall is high, at 2.4 m centres up to 1.2 m high and 1.8 m centres above that.
- Drainage: 300 mm of gravel behind the wall plus 10% extra, a perforated agricultural pipe along the base, and geotextile against the soil.
| Example | Face | Sleepers | Posts | Gravel | Installed cost |
|---|---|---|---|---|---|
| Treated pine, 10 m x 0.8 m | 8 m² | 21 | 6 x 1.6 m | 2.6 m³ | $1,600 to $3,600 |
| Concrete sleepers, 12 m x 0.6 m | 7.2 m² | 16 | 6 x 1.2 m | 2.4 m³ | $2,016 to $3,960 |
| Rendered reinforced block, 8 m x 1.2 m | 9.6 m² | n/a | n/a | 3.2 m³ | $2,400 to $7,600, plus an engineer |
| Treated pine garden edge, 15 m x 0.4 m | 6 m² | 15 | 8 x 0.8 m | 2.0 m³ | $1,500 to $3,750 |
Retaining wall cost by material
These are indicative installed prices per square metre of face for walls about 1 m high, drawn from published Australian guides. Most come from contractor and lead-generation sites, and they disagree widely, so we show ranges and no single figure.
| Wall type | Per m² (about 1 m high) | Typical lifespan quoted | Notes |
|---|---|---|---|
| Treated pine sleepers | $200 – $450 | 15 to 20 years | Cheapest for low walls; use H5 posts |
| Concrete sleepers with steel posts | $280 – $550 | 25 to 50+ years | Pioneer rate their 2.4 m sleepers for walls to 600 mm only |
| Segmental (interlocking) block | $300 – $650 | Not published | Quote Yard lists $280 to $450; one contractor lists $460 to $790 ex GST |
| Reinforced block, rendered (besser) | $450 – $900 | 60+ years | Sources disagree by about 2x; render is rarely priced separately |
| Sandstone | $300 – $750 | Not published | Hand-placed or boulder walls cost most |
| Gabion | $300 – $800 per metre | Not published | Only a per-metre figure at about 1 m is published; no Australian per-m² price found |
Cost by wall height
| Height | Per lineal metre | What changes |
|---|---|---|
| Under 0.5 m | $100 – $250 | Often DIY; no approval in most states |
| 0.5 to 1 m | $200 – $750 | Depends on material; NSW approval above 600 mm |
| 1 to 1.5 m | $300 – $950 | Engineer and permit usually needed |
| 1.5 to 2 m | $550 – $1,500 | Deeper footings, heavier posts or block |
| Over 2 m | $1,000 – $2,500+ | Geotechnical report and full engineering |
Council approval and engineers by state
- NSW: the NSW Government information sheet on earthworks and retaining walls says walls up to 600 mm above or below ground can be exempt if they are at least 1 m from the boundary, easements and sewer or water mains, and meet other conditions. That sheet dates from 2015, so confirm with your council or a certifier. Taller walls need a certifier or council approval, and an engineer where they are over 600 mm and within 1 m of the boundary or over 1 m elsewhere.
- Victoria: walls under 1 m are generally exempt unless they are tied to other building work or protect a neighbour’s property, and councils say walls of 1 m or more need a building permit. Some councils require a structural engineer’s design and certification. Check the current regulations with your council.
- Queensland: a wall is exempt only if it has no surcharge in its zone of influence, is 1 m or less high, and is at least 1.5 m from a building or another retaining wall. Walls that need approval need an RPEQ engineer. A surcharge means a load such as a driveway above the wall.
- Elsewhere: South Australia and the ACT use similar height thresholds (about 1 m and 1.5 m according to guides we found), but rules differ by council, so ask yours.
- Standard: engineered walls are designed to AS 4678 for walls 0.8 to 15 m high, which is the deemed-to-satisfy route under the NCC.
Drainage, footings and materials
- Drainage: geotextile against the soil, a 65 to 100 mm agricultural pipe at the base and about 300 mm of free-draining gravel behind the wall. Brisbane City Council’s reinforced block drawing (BSD-2222) also shows weepholes at 1 m centres. Pioneer finishes concrete sleeper walls with a clay plug at the top.
- Posts and footings: Galintel’s guide for a 1 m timber sleeper wall uses 450 mm holes about as deep as the wall is high, with 100 mm of concrete under the post and N25 concrete. Use our concrete calculator to turn the volume into bags.
- Sleepers: Bunnings lists 200 x 75 mm treated pine sleepers at about $29 to $34 for 2.4 m, and concrete sleepers at $67 to $75 each by special order. Specialist yards charge about $38 to $40 for a 200 x 75 x 2.4 m H4 sleeper.
- Steel posts: galvanised 100UC posts for 75 mm sleepers are about $51 for 0.9 m, $69 for 1.2 m and $100 for 1.8 m at Bunnings. Pioneer’s rule is a post about twice the wall height.
- Hazard class: Wood Solutions recommends H5 or Class 1 hardwood for retaining walls. H4 is used for low DIY walls, but it is not rated for critical structural elements.
- Gabions: Australian suppliers use 50 x 50 mm mesh in 4 to 5 mm wire but publish no basket prices, so we show a per-metre range only.
What is not in the price
- Excavation and soil removal: lead-generation guides quote a mini excavator with an operator at about $90 to $160 an hour and soil removal at about $40 to $80 per m³. These are low-confidence figures, so ask for them separately.
- Engineer: typically $500 to $2,000 per job, and a geotechnical report $500 to $2,500.
- Permit fees: Victorian council schedules range from about $770 (Whittlesea 2024-25) to $1,512 to $1,835 (Macedon Ranges 2025-26), plus lodgement and levies.
- Removal of an old wall, tree roots or services: quoted separately.
Common mistakes
- No drainage. Water pressure behind the wall is the main reason walls fail.
- Assuming a 1 m price works for a 2 m wall. Costs rise faster than the area does.
- Ignoring loads above the wall. A driveway, pool or building turns a garden wall into an engineered one.
- Building near a boundary without approval. This is where neighbours and councils get involved.
- Using H4 timber for taller walls. Guides recommend H5 or hardwood for structural retaining walls.
- Short posts. A post set shallower than about the wall height will tilt.
Frequently asked questions
How much does a retaining wall cost per square metre in Australia?
Published guides put a retaining wall at roughly $200 to $450 per m² for treated pine sleepers, $280 to $550 for concrete sleepers with steel posts, $300 to $650 for segmental block, $450 to $900 for rendered reinforced block, and $300 to $750 for sandstone, for walls about 1 m high. The sources disagree by up to twice, so treat these as a range and get at least three quotes.
How much does a retaining wall cost per metre?
At about 1 m high, most walls cost $200 to $750 per lineal metre depending on the material. Guides put walls under 0.5 m at about $100 to $250 per metre, 1 to 1.5 m at $300 to $950, 1.5 to 2 m at $550 to $1,500, and over 2 m at $1,000 to $2,500 or more, because taller walls need an engineer, deeper footings and heavier posts.
Do I need council approval for a retaining wall?
It depends on height, loads and distance from boundaries. NSW guidance treats walls up to 600 mm as exempt if they are at least 1 m from the boundary and meet other conditions. Victorian councils generally say walls under 1 m do not need a permit unless they are tied to other building work or protect a neighbour’s property. In Queensland a wall is exempt only if it is 1 m or less, carries no surcharge and is at least 1.5 m from a building or another retaining wall. Check with your council before you build.
When do I need an engineer for a retaining wall?
As a rule, for any wall over about 1 m, any wall carrying a load such as a driveway, building, pool or steep slope above it, and walls over 600 mm close to a boundary. Councils usually ask for an engineer’s design before they approve these walls. An engineer typically costs $500 to $2,000 per job, plus a geotechnical report ($500 to $2,500) if the ground is poor.
What is the cheapest retaining wall?
Treated pine sleepers on steel or timber posts are usually the cheapest for walls under 1 m, at roughly $200 to $450 per m² installed. They last around 15 to 20 years in many guides, while concrete sleepers and reinforced block are quoted at 25 to 60 years or more, so the cheapest upfront wall is not always the cheapest over its life.
How long do timber retaining walls last?
Lead-generation guides quote 15 to 20 years for treated pine, though one Sydney contractor quotes 20 to 30 years for H4 hardwood. Hazard class matters: Wood Solutions recommends H5 or Class 1 hardwood for retaining walls rather than H4, which Bunnings sells as the minimum for DIY. Use H5 for posts and structural walls and treat H4 as acceptable only for low garden walls.
How much drainage does a retaining wall need?
Every wall needs drainage, because trapped water is what pushes walls over. Manufacturer details call for geotextile against the soil, a 65 to 100 mm agricultural pipe at the base, and about 300 mm of free-draining gravel behind the wall. Allow roughly $30 to $90 per metre of wall for drainage.
Can I build a retaining wall myself?
Low walls are a realistic DIY job. One guide says under 600 mm is feasible for a DIYer, while Bunnings advises professional advice above 400 mm or near a boundary or load. Whatever the height, dig properly for the footings, drain the wall and check approval rules first.
Related tools
- Landscaper rates - hourly rates and typical job prices
- Concrete calculator - footings, slabs and bags
- Soil, mulch and gravel calculator - drainage gravel and backfill
- Renovation quote comparator - paste retaining wall quotes for red-flag analysis
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