Work out the materials for a retaining wall in Australia. Choose a sleeper, block or poured concrete wall, then get the sleepers, posts, blocks, concrete, drainage gravel and ag pipe to order.
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The drawing shows the layout, not a design. Thin parts are drawn larger so the labels can be read.
Concrete Order
0m³
Planning quantities. Add spares, cuts and caps, and confirm them against your plans.
This retaining wall calculator turns your wall length and height into a shopping list. It counts sleepers, posts, blocks, concrete, drainage gravel and ag pipe. It is built for Australian products and sizes.
The biggest number in the retaining wall calculator is the Concrete Order, as concrete is often the part people get wrong. The materials list then changes with the wall type:
The retaining wall calculator also shows a height note, as walls near 1 m often need approval. To size a plain wall by itself, see the Concrete Wall Calculator, which also covers block fill in detail.
A retaining wall holds back a heavy load of soil and water, and a failed wall can hurt people. This calculator counts materials. It does not design a wall, and it can't tell you if a wall is safe. Post size, post depth, footing size, steel and drainage must come from your plans, a product guide or an engineer.
Take extra care when there is a house, driveway, pool, fence or slope above the wall. These add load, which engineers call surcharge. Published guides assume limited loads. The Hanson block guide uses 2.5 kPa for walls up to 1.5 m and 5 kPa above that, and the Adbri guide assumes 2.5 kPa. Brisbane City Council says vehicles should stay at least one wall height back from the wall. If your site is not like the one in the guide, the guide does not apply.
Never dig near the base of an existing wall or a neighbour's footing without advice. Trenches can collapse, and an excavation can undermine a nearby structure. Lodge a Before You Dig Australia request before any digging.
Rules differ by state and council, and they change. The table shows examples only, so always check yours. Height is usually measured with the cut or fill the wall retains, not just the visible face.
| Place | Published Rule | Other Conditions |
|---|---|---|
| NSW exempt development | No higher than 600 mm above existing ground | At least 1 m from any boundary. Tiers at least 2 m apart |
| Brisbane | Under 1 m with no building approval needed | No surcharge. At least 1.5 m from any building or other retaining wall |
| Gympie, Queensland | Up to 1 m as accepted development | No surcharge. Over 1 m within 1.5 m of a side or rear boundary needs siting approval |
| Victoria, general guide | Permits generally required over 1 m | Engineering typically required over 1.5 m |
Gympie also says a building application needs a design certified by an RPEQ, a Queensland registered engineer, unless the wall is accepted development. What's The Damage says engineer certification is required for walls over 1 m in most states, and walls over 2 m need a structural engineer. A wall can also need approval near sewers, stormwater mains or easements, as Gympie notes.
Boundary walls need extra thought. Keep the wall, footings, drainage and backfill on your own land where you can. If a fence sits on top, it adds load and may affect the height limit. Wollondilly says the Dividing Fences Act may apply where a wall supports a boundary fence. Talk to your neighbour early, and get advice if the two levels differ.
| Wall | Good For | Keep In Mind |
|---|---|---|
| Concrete sleeper | Long, straight walls and tight budgets | Needs deep post holes and heavy lifting |
| Timber sleeper | Low garden walls | Shorter life than concrete |
| Segmental block | Curves, low to medium walls, DIY | Height limited without engineering |
| Concrete block | Tall, strong walls near boundaries | Needs a footing, steel and core fill |
| Poured concrete | Tight spots and high loads | Needs engineering, formwork and steel |
Height and load usually decide the choice. If the wall is on a boundary and the soil is deep, a block or poured wall has a smaller base than some other options. Where there is room to step the wall into two low tiers, that can avoid a single tall wall. Ask your council how it treats tiers.
A retaining wall calculator is only as good as your measurements. Run a string line along the wall, and measure the length along it. For height, measure from the finished low ground to the finished top of the wall, not from the top of the footing.
Add a few spare blocks or a sleeper for breakages and cuts, as the tool gives exact counts. Nuway's Brisbane list shows delivery terms too, such as $119.90 to $215 minimum charges on small orders, depending on the brand. So check your delivery before you settle on a block.
The post hole figure ignores the small volume of the post, which offsets some waste. Block fill rates come from the Concrete Masonry Handbook: 0.054 m³ per m² for 150 series, 0.083 for 200 series, and 0.18 for 300 series, with every core filled. See How We Calculate Concrete for our method.
Each example uses 10% concrete waste, rounding to the next 0.1 m³, and 300 mm of drainage gravel. Enter the same numbers in the retaining wall calculator and you will get the same results. Footing and hole sizes are examples only, not a design.
With 2 m sleepers, that is 5 bays and 6 posts. At 200 mm a sleeper, the wall has 4 courses, so 5 × 4 = 20 sleepers. Say the post holes are 450 mm wide and 0.8 m deep. Each is 0.127 m³, so six come to 0.763 m³, or 0.839 m³ with waste. Order 0.9 m³, or 91 of the 20 kg bags. Each post is about 1.6 m long.
The wall face is 12 m², so that is 150 blocks and 6 courses. In 200 series, core fill is 12 × 0.083 = 0.996 m³. A 1,200 × 300 mm footing adds 3.600 m³. The total is 4.596 m³, or 5.056 m³ with waste, so order 5.1 m³. Core fill and the footing are usually poured on different days, so split the order.
The wall face is 6.4 m². Versawall comes at 12.5 units per m², which gives 80 units and 4 courses. A 450 × 150 mm levelling pad is 0.540 m³, or 0.6 m³ to order. Adbri publishes 800 mm plus a cap for Versawall without engineering, so this wall is at that limit.
A 200 mm wall is 8 × 1.2 × 0.2 = 1.920 m³. A 1,200 × 300 mm footing is 2.880 m³. Together that is 4.800 m³, or 5.280 m³ with waste, so order 5.3 m³. A wall like this needs an engineer's design, so the sizes here only show the sum. The formwork is 19.2 m² across both faces.
The gravel is 10 × 0.3 × 0.8 = 2.40 m³, or about 3.6 t at 1.5 t/m³. You also need 10 m of ag pipe plus the run to the outlet, and about 24 m² of geofabric to wrap the gravel.
This chart covers a 10 m sleeper wall with 2 m sleepers at 200 mm high, and a 300 mm gravel strip. It gives a quick idea of how materials grow with height. Check your own numbers in the tool.
| Wall Height | Courses | Sleepers | Wall Face | Drainage Gravel | Gravel Weight |
|---|---|---|---|---|---|
| 0.6 m | 3 | 15 | 6 m² | 1.8 m³ | 2.7 t |
| 0.8 m | 4 | 20 | 8 m² | 2.4 m³ | 3.6 t |
| 1.0 m | 5 | 25 | 10 m² | 3.0 m³ | 4.5 t |
| 1.2 m | 6 | 30 | 12 m² | 3.6 m³ | 5.4 t |
| 1.6 m | 8 | 40 | 16 m² | 4.8 m³ | 7.2 t |
Posts do not change with height, but their size and depth usually do. A 1.6 m wall needs far more post than a 0.6 m wall, even though the post count stays at 6. Those sizes must come from your plans.
Sleeper walls are popular because they go up quickly. Steel posts sit in concrete piers, and sleepers slide in between them. Daisy's Garden Supplies lists lengths of 1.8, 2.0, 2.4 and 3.0 m, in 80 mm thick standard and 100 mm thick heavy-duty sleepers. A sleeper is usually 200 mm high, so five courses give you 1 m.
Sleepers are heavy, so plan how you will lift them. Timber sleepers are lighter, but they rot in time, and they need treatment rated for ground contact. Use the Concrete Post Hole Calculator for more detail on post hole concrete.
Reinforced block walls suit taller walls and tight sites. The Hanson guide covers walls up to 3 m for residential and light commercial work, and says all cores must be fully grouted. Brisbane City Council's standard drawing BSD-2222 shows how much the footing grows with height. These figures are for one council's set conditions, at 5 kPa surcharge with level backfill, so don't copy them for your own site.
| Wall Height | Footing Width, Level Backfill | Block Series |
|---|---|---|
| Up to 800 mm | 900 mm | 150 series |
| 801 to 1,000 mm | 1,050 mm | 150 series |
| 1,001 to 1,200 mm | 1,200 mm | 150 series |
| 1,201 to 1,400 mm | 1,350 mm | 200 series |
| 1,401 to 1,600 mm | 1,500 mm | 200 series |
| 1,601 to 1,800 mm | 1,650 mm | 200 series |
Those values were read from the drawing text, so check the original. The drawing also calls for 25 MPa grout, while Hanson mentions 20 MPa, so follow your own plans. Brisbane says not to backfill until core fill reaches 20 MPa, and to place expansion joints no more than 12 m apart. A footing that wide takes a lot of concrete, which is why it often matters more than the core fill. For pouring core fill, see the Concrete Wall Calculator, and use the Concrete Footing Calculator for the base.
Segmental blocks stack without mortar, and they suit DIY jobs and curves. Adbri publishes these heights without engineering. Walls above them need an engineer's design.
| Block | Size (L × H × D) | Units Per m² | Unreinforced Height |
|---|---|---|---|
| Versawall | 400 × 200 × 215 mm | 12.5 | 800 mm + cap |
| Versaloc | 400 × 200 × 190 mm | 12.5 | 600 mm + cap |
| Duostone or Flagstone | 300 × 100 × 160 mm | 33.33 | 700 mm + cap |
| Windsor Stone | 295 × 130 × 203 mm | 26 | 1,040 mm, council approval advised |
Sizes in the table are read from a brochure, so check them with the maker before you order. Adbri's details call for a compacted base or concrete pad about 400 to 450 mm wide and 130 to 150 mm deep. It says walls over 800 mm need a 20 MPa concrete levelling pad, while smaller walls can use 5% cement-stabilised crushed rock. Its limits assume a 2.5 kPa surcharge and insitu soil, with free-draining 10 to 20 mm aggregate behind the wall. If you choose stabilised rock, the concrete figure in the tool shows the pad volume to order.
A poured wall uses formwork, steel and a footing, and it almost always needs an engineer. It suits walls with heavy loads or very little room. The footing often uses more concrete than the wall itself, so don't size only the visible part. Enter both in the tool.
These pours are usually done in stages. The footing goes first with starter bars, then the wall is poured after forms and steel are in place. Each stage is a separate delivery, so use the Concrete Estimator to plan pour days and short-load fees, and the Concrete Ready Mix Calculator for truck timing. Wall pours push hard on forms, so have them designed properly.
Water is a common reason walls fail. Wet soil is heavier, and it pushes harder on the wall. So drainage is part of the structure, not an extra. Published details have a lot in common.
| Item | Published Figure | Source |
|---|---|---|
| Gravel behind the wall | About 300 mm wide | Hanson, Brisbane City Council, Australian Landscape Supplies |
| Ag pipe | 100 mm slotted or socked pipe at the base | Hanson, Adbri |
| Pipe fall | 2%, or 1 in 200 minimum | Adbri, Brisbane City Council |
| Outlets | At no more than 20 to 25 m | Adbri, Brisbane City Council |
| Weep holes | 50 mm uPVC at 1,200 mm centres | Hanson |
| Soil cap on top | 150 to 300 mm, compacted | Australian Landscape Supplies |
Wrap the gravel in geofabric so soil does not clog it. Place the pipe at the base, then lead it to a place where water can leave, such as a stormwater system or beyond the end of the wall. Don't aim it at a neighbour. Divert surface water away from the back of the wall too. Taller walls may need a second pipe, as Hanson notes.
The tool counts gravel as a strip the full height of the wall. For gravel in more detail, see our Crushed Stone Calculator, which covers blue metal and tonnes per cubic metre.
These are installed prices from What's The Damage, verified in November 2026. The site says its per metre figures include footings at about 1 m height.
| Wall | Low | Typical | High |
|---|---|---|---|
| Timber sleeper | $200 | $320 | $450 |
| Concrete sleeper, 1 m high | $300 | $450 | $600 |
| Concrete sleeper, 1.5 m high | $400 | $600 | $950 |
| Block, 1 m high | $350 | $550 | $750 |
| Limestone block, 1 m high | $280 | $420 | $600 |
| Engineered block, 1.5 to 2 m high | $550 | $930 | $1,500 |
| Gabion | $300 | $500 | $800 |
Per square metre, Yellow Pages gives $480 to $700 for reinforced concrete blocks and $550 to $850 for Besser blocks, in an article updated in May 2026. For materials alone, Nuway lists many segmental blocks in Brisbane at about $150 to $190 per m² in February 2026, such as Versawall at $180 and Trendstone at $156, with Versaloc at $79.75 before core fill and steel. Those are prices for the blocks only.
| Item | Published Cost | Source |
|---|---|---|
| Drainage behind the wall | $30 to $80 per metre | What's The Damage |
| Old wall removal | $50 to $180 per metre | What's The Damage |
| Engineer certification | $500 to $2,000 per job | What's The Damage |
| Soil report | $500 to $2,500 per job | What's The Damage |
| Council or building approval | $450 to $1,800 per job | What's The Damage |
| Labour | $60 to $100 an hour | Yellow Pages |
As an example, a 10 m concrete sleeper wall 1 m high at the typical $450 per metre comes to $4,500. Add $500 for drainage at $50 per metre, for a total of $5,000. Engineering or approval, if needed, comes on top. Enter your own rates under Cost, and use Other Costs for engineers, permits or demolition. Height moves the price fast, so use the retaining wall calculator to test a lower wall or two tiers. Doubling height can more than double the cost, as footings and engineering grow too.
Australian Landscape Supplies advises keeping heavy loads at least one wall height away from the wall. If you are pouring a slab or path nearby, plan the levels with the Concrete Slab Calculator.
Cutting blocks or concrete sleepers creates dust containing silica. Read Safe Work Australia's silica guidance and wear suitable protection. Sleepers and blocks are heavy, so plan your lifts.
Start with the length and height, then pick the wall type. A 10 m by 0.8 m sleeper wall with 2 m sleepers takes 20 sleepers and 6 posts. Enter your post holes to get the concrete.
Divide the length by the sleeper length, and round up. Divide the height by the sleeper height, and round up. Multiply the two. A 10 m by 1 m wall takes 25 sleepers of 2 m by 200 mm.
Each 450 mm hole, 0.8 m deep, takes 0.127 m³. Six holes take 0.763 m³ before waste. Your hole size must come from your plans or post guide.
It depends on the wall, soil and post. One system guide says about half the post goes below ground. Use your design, not a rule of thumb, for a real wall.
It varies. NSW exempt rules start at 600 mm, and many Queensland rules use 1 m with conditions. Check with your council before you build.
Published guides say engineer certification is required for walls over 1 m in most states. You may need one for lower walls if there is a load above.
Published details use about 300 mm of gravel behind the wall, with a 100 mm slotted ag pipe at the base, wrapped in geofabric, and an outlet to a safe place.
Published 2026 figures put a 1 m concrete sleeper wall at about $300 to $600 per metre, installed. Block walls cost more. Height, access and engineering all change the price.
Timber sleepers are usually among the cheapest on published figures, at about $200 to $450 per metre. They usually do not last as long as concrete.
Standard 400 × 200 mm blocks work out at 12.5 per m². Segmental blocks vary, so check your product.
Only if the design allows for it. A fence adds load, and it can affect height limits. Brisbane says fences should not be fixed to its standard block wall.
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Figures reviewed November 2026. Sources: Hanson, Adbri Masonry, Concrete Masonry Handbook, Brisbane City Council, Gympie Regional Council, Wollondilly Shire Council, What's The Damage, Yellow Pages, Nuway and others linked in the sections above. This page gives planning quantities, not a wall design. Confirm your design, approvals and quantities with your council, your engineer and the people responsible for your project. See our Disclaimer and Calculator Methodology.