Frequently Asked Questions

Question 1

Should I use 75mm or 100mm concrete sleepers?

Accepted Answer

75mm concrete sleepers suit lower walls — generally up to around 600–900mm exposed height — in standard residential conditions. 100mm sleepers are recommended for taller walls, heavier surcharge loads (driveways, vehicles, structures near the wall) or where an engineer specifies a thicker section. For walls over 1.0m or in any situation with significant loading, always confirm the sleeper and post specification with a structural engineer. FPM stocks both 75mm and 100mm sleepers in all finishes.

Question 2

How many concrete sleepers do I need?

Accepted Answer

Divide your wall length by the sleeper length to get sleepers per course, then divide the wall height by the sleeper thickness (75mm or 100mm) to get the number of courses. Multiply the two for your total, then add 5–10% for waste and cuts. For example: a 10m long × 600mm high wall using 2400mm × 75mm sleepers needs approximately 5 sleepers per course × 8 courses = 40 sleepers. Use the free FPM retaining wall estimator at /estimator for an accurate count including posts, drainage and concrete.

Question 3

What concrete sleeper finishes and colours are available?

Accepted Answer

FPM Building Supplies stocks concrete sleepers in Plain/Smooth, Charcoal, Woodgrain, Blockface and Stackstone finishes. Sleepers are available in natural grey and charcoal colourways depending on the finish. All finishes are available in 75mm and 100mm thickness. Visit the concrete sleepers category page or contact our Epping warehouse to confirm current stock.

Question 4

Are your concrete sleepers reinforced with steel?

Accepted Answer

Yes. FPM concrete sleepers are reinforced with steel and manufactured to 50 MPa compressive strength. The reinforcement provides the tensile strength needed to span between posts and resist the lateral earth pressure of a retaining wall. Engineering data sheets are available on request.

Question 5

How long do concrete sleepers last?

Accepted Answer

Properly installed concrete sleepers can last 50 years or more. Reinforced concrete is highly resistant to rot, termites, UV and moisture — the main causes of premature failure in timber sleepers. Longevity depends on correct drainage behind the wall (to prevent hydrostatic pressure build-up), correct post sizing and footing depth, and quality of installation.

Question 6

Are concrete sleepers better than timber sleepers?

Accepted Answer

For most retaining wall applications, yes. Concrete sleepers are rot-proof, termite-resistant, require no ongoing treatment and maintain their structural integrity over decades. Timber sleepers (hardwood or treated pine) are lower cost upfront but typically last 10–25 years before requiring replacement, and can be subject to rot, termite attack and warping. Concrete sleepers are the preferred choice for permanent retaining walls in Victoria.

Question 7

Can concrete sleepers be cut to size?

Accepted Answer

Concrete sleepers can be cut using a diamond blade angle grinder or concrete saw, but cutting reinforced concrete requires care and the right equipment. For most projects it is more practical to design the wall layout around standard sleeper lengths (typically 1800mm, 2000mm, 2400mm and 2700mm). Contact FPM to discuss your project requirements.

Question 8

How heavy are concrete sleepers?

Accepted Answer

A standard 2400mm × 200mm × 75mm concrete sleeper weighs approximately 85–95 kg. A 2400mm × 200mm × 100mm sleeper weighs approximately 110–120 kg. Sleepers require mechanical handling equipment (forklift, crane or sleeper grabber) for safe installation. FPM stocks sleeper grabbers and can advise on handling requirements.

Question 9

What steel posts do I need for a concrete sleeper retaining wall?

Accepted Answer

The most common posts for concrete sleeper retaining walls are galvanised H posts (100UC, 150UC) for standard in-line positions, C posts (end posts) for wall ends and corners, and 45° and 90° corner posts for direction changes. Post size depends on wall height, surcharge loading and footing depth — an engineer should specify post size for walls over 1.0m. FPM stocks the full range of galvanised steel H posts, C posts and corner posts.

Question 10

How deep should retaining wall posts be set in the ground?

Accepted Answer

As a general guide, retaining wall posts should be set to a depth of approximately one-third to one-half of the total post length below ground. The required footing depth depends on wall height, soil conditions, surcharge loading and engineering requirements. For walls over 1.0m or in poor soil conditions, a structural engineer should specify the footing depth. FPM can provide engineering data sheets for our galvanised steel H post systems on request.

Question 11

How far apart should retaining wall posts be?

Accepted Answer

Post spacing is determined by the sleeper length. For 2400mm sleepers, posts are typically spaced at 2400mm centres. For 1800mm or 2000mm sleepers, posts are spaced accordingly. The sleeper must span fully between posts with no overhang beyond the post centreline. Always confirm post spacing with the engineering data for the wall system you are using.

Question 12

What is the difference between 100UC and 150UC steel posts?

Accepted Answer

100UC (Universal Column) posts are the standard choice for residential retaining walls up to approximately 1.0–1.2m exposed height in typical soil conditions. 150UC posts are heavier and stronger, used for taller walls, walls with significant surcharge loads (driveways, vehicles, structures) or where an engineer specifies a larger section. FPM stocks 100UC and 150UC galvanised H posts.

Question 13

Do I need engineering for a concrete sleeper retaining wall?

Accepted Answer

Engineering requirements depend on wall height, location, loads, soil conditions and local regulations. In Victoria, retaining walls over 1.0m in height generally require a building permit and engineering documentation. Walls close to boundaries, structures, driveways or in poor soil conditions may require engineering at lower heights. FPM can supply engineering data sheets for our wall systems — but for site-specific advice, consult a structural engineer or your local council.

Question 14

Do I need a permit for a retaining wall in Victoria?

Accepted Answer

In Victoria, retaining walls over 1.0m in height typically require a building permit under the Building Regulations 2018. Walls under 1.0m may still require a permit depending on proximity to boundaries, drainage, structures or other site-specific factors. Requirements vary by council — always confirm with your local council or a registered building practitioner before commencing work.

Question 15

What is the maximum height for a concrete sleeper retaining wall?

Accepted Answer

There is no single universal maximum height — allowable height depends on the engineered wall system, post size and spacing, footing depth, soil conditions and surcharge loading. Walls over 1.0m require engineering and a building permit in Victoria. FPM can supply engineering data sheets for our standard wall systems. For walls over 1.5m or in challenging site conditions, engage a structural engineer.

Question 16

Can I get engineering documentation for FPM retaining wall systems?

Accepted Answer

Yes. Engineering computation sheets for FPM concrete sleeper and steel post retaining wall systems are available on request. Contact our Epping warehouse by phone or email and we can supply the relevant documentation for your wall height and post size.

Question 17

Do I need drainage behind a concrete sleeper retaining wall?

Accepted Answer

Yes — drainage is essential behind any retaining wall. Without drainage, hydrostatic water pressure builds up behind the wall and is one of the most common causes of retaining wall failure. A correctly installed drainage system includes: 90mm slotted ag pipe (drainage pipe) at the base of the wall behind the sleepers, wrapped in geofabric to prevent silt ingress, surrounded by drainage aggregate (20mm crushed rock), directed to a suitable outlet. FPM stocks ag pipe, geofabric and drainage aggregate at our Epping warehouse.

Question 18

What should I put behind a concrete sleeper retaining wall?

Accepted Answer

Behind a concrete sleeper retaining wall you need: drainage aggregate (20mm crushed rock) directly behind the sleepers, geofabric (geotextile) to separate the drainage aggregate from the retained soil and prevent silt migration, a 90mm slotted ag pipe at the base of the drainage aggregate layer, and suitable backfill behind the drainage layer. The drainage system must have an outlet to allow water to escape — typically to a stormwater drain, swale or daylight at the end of the wall.

Question 19

What size ag pipe should I use behind a retaining wall?

Accepted Answer

90mm slotted ag pipe (agricultural drainage pipe) is the standard size for residential retaining wall drainage. It provides adequate flow capacity for most residential applications. The ag pipe should be wrapped in geofabric sock or laid within a geofabric-lined trench to prevent silt blockage. FPM stocks 90mm ag pipe at our Epping warehouse.

Question 20

Can I install a Colorbond fence on top of a concrete sleeper retaining wall?

Accepted Answer

Yes — Colorbond fencing can be installed on top of a concrete sleeper retaining wall, but the design must account for the combined wind and structural loads on the retaining wall posts. The retaining wall posts need to be sized to handle both the retaining wall loads and the fence loads. FPM stocks concrete plinths (2360mm length) designed to sit under standard 2365mm Colorbond fence panels, as well as Colorbond fence panels, C-channel posts, rails and accessories.

Question 21

Can concrete sleepers be used under a Colorbond fence?

Accepted Answer

Yes. FPM stocks 2360mm concrete plinths specifically designed to sit under standard 2365mm Colorbond fence panels. The plinth sits at ground level and provides a solid, rot-proof base for the Colorbond fence, keeping the steel panels off the ground and preventing corrosion at the base. This is a popular solution for boundary fences on level or gently sloping ground.

Question 22

What Colorbond colours does FPM stock?

Accepted Answer

FPM Building Supplies stocks Colorbond fence panels, C-channel posts and rails in Monument, Woodland Grey, Basalt and Night Sky. These are among the most popular Colorbond colours for residential fencing in Melbourne. Contact our Epping warehouse to confirm current stock availability in your preferred colour.

Question 23

Do you deliver retaining wall materials across Victoria?

Accepted Answer

Yes. FPM Building Supplies delivers concrete sleepers, steel posts and all retaining wall materials across Victoria. Delivery is $100 GST-inclusive per commenced 10 km from our Epping warehouse (postcode 3076), capped at $1,000 for distances up to 100 km. For delivery beyond 100 km, contact us for a quote. Free pickup is available from our Epping warehouse.

Question 24

How much does delivery cost?

Accepted Answer

Delivery is charged at $100 GST-inclusive per commenced 10 km from our Epping warehouse (3076). For example: 0–10 km = $100, 11–20 km = $200, 21–30 km = $300, and so on up to a cap of $1,000 for 91–100 km. Pickup from our Epping warehouse is always free. Use the quote cart on our website to get an estimated delivery cost for your address.

Question 25

Can you deliver directly to a job site?

Accepted Answer

Yes. FPM delivers directly to job sites across Melbourne and Victoria. Please ensure the site has safe, suitable access for a delivery vehicle and forklift. Advise us of any access restrictions, overhead powerlines, soft ground, narrow driveways or other hazards before delivery. Our drivers reserve the right to decline entry to unsafe sites.

Question 26

Can I collect concrete sleepers directly from FPM Building Supplies?

Accepted Answer

Yes. Free pickup is available from our Epping warehouse at 32 Fullarton Drive, Epping VIC 3076. We are open Mon–Fri 7 am–5 pm and Saturday 7 am–3 pm. Please call 0421 370 700 to confirm stock availability before visiting. Ensure your vehicle or trailer is suitable for the weight and size of the materials you are collecting.

Question 27

Do you offer trade pricing or bulk pricing?

Accepted Answer

Yes. FPM Building Supplies offers trade accounts for landscapers, builders, fencing contractors and other trade customers. Approved trade account holders receive 10% off their first eligible purchase of $2,000 or more, and 10% ongoing discount on concrete sleepers and retaining wall steel. Apply for a trade account online at /trade-account or contact our Epping warehouse.

Question 28

Do you supply retaining wall materials to landscapers, builders and fencing contractors?

Accepted Answer

Yes. FPM Building Supplies is a trade supplier to landscapers, builders, fencing contractors, civil contractors and owner-builders across Melbourne and Victoria. We stock the full range of concrete sleepers, galvanised steel posts, drainage products, Colorbond fencing, timber fencing and accessories. Contact us or apply for a trade account online.

Question 29

How much does a concrete sleeper retaining wall cost per metre?

Accepted Answer

Material costs vary depending on wall height, sleeper finish, sleeper thickness and the steel post size required. As a rough guide, materials for a standard 1.0m high wall using plain 75mm concrete sleepers and 100UC galvanised H posts typically range from $150–$250 per lineal metre (materials only, GST-inclusive, excluding installation, drainage and concrete). Taller walls, decorative finishes or heavier steel posts will increase material costs. Use the free FPM estimator at /estimator for a detailed material cost estimate, or call 0421 370 700 for a quote.

Question 30

Do you sell complete retaining wall materials?

Accepted Answer

Yes. FPM Building Supplies stocks everything you need for a complete concrete sleeper retaining wall: concrete sleepers (all finishes and thicknesses), galvanised steel H posts, C posts and corner posts, drainage aggregate, geofabric, ag pipe, concrete for post footings, sleeper grabbers and installation accessories. You can get a complete materials list and estimate using our online estimator at /estimator.

Concrete Sleepers

Steel Posts

Engineering & Permits

Drainage

Colorbond Fencing

Delivery & Pickup

Trade & Pricing

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