How many sleepers for a raised garden bed? Australian sizes and a full materials list
Short answer
For a 2.4 × 1.2 m bed built from standard 200 mm-high sleepers, you need 3 sleepers (2.4 m long) per course — two for the sides and one cut in half for the ends. A 400 mm-high bed (two courses) takes 6 sleepers, plus corner posts, 100 mm galvanised screws and about 1 m³ of soil. For vegetables, choose H4 timber with a copper-based treatment such as MicroPro rather than CCA, or line the bed.
A sleeper garden bed is one of the best first DIY builds: no approvals, no licences, and a weekend’s work. The only tricky part is working out how much to buy — so here’s the maths.
Sleeper sizes in Australia
The common garden sleeper is 200 × 50 mm H4 treated pine, sold in lengths of 1.2, 1.8, 2.4, 2.7, 3.0 and 3.6 m. Each sleeper laid on its edge gives you one 200 mm course of height.
| Bed height | Courses |
|---|---|
| 200 mm | 1 |
| 400 mm | 2 |
| 600 mm | 3 (comfortable to work at without bending much) |
How many sleepers: worked examples
Plan the bed around sleeper lengths so you cut as little as possible.
| Bed size (outside) | Sleepers per course | For 400 mm high (2 courses) | For 600 mm high (3 courses) |
|---|---|---|---|
| 2.4 × 1.2 m | 3 × 2.4 m (2 sides + 1 cut in half for the ends) | 6 | 9 |
| 3.0 × 1.5 m | 3 × 3.0 m (2 sides + 1 cut in half for the ends) | 6 | 9 |
| 1.8 × 0.9 m | 3 × 1.8 m (2 sides + 1 cut in half for the ends) | 6 | 9 |
The formula: sleepers per course = 2 (sides) + 1 (cut in half for the two ends, when the width is half the length). If your width isn’t exactly half the length, count the ends separately: ends ÷ sleeper length, rounded up.
The full shopping list
For a 2.4 × 1.2 × 0.4 m bed:
- 6 × 200 × 50 mm × 2.4 m sleepers (H4 treated)
- 4 corner posts, cut from offcuts or a post, at least bed height plus the depth you’ll sink them
- Galvanised screws, at least 100 mm long, for the corners and into the posts — Bunnings’ guide uses 100 mm bugle batten screws
- Bitumen paint for any timber going into the ground
- Liner (builder’s plastic or geotextile) for the inside walls
- About 1 m³ of soil (see below)
How much soil?
Soil volume = internal length × internal width × fill height.
For a 2.4 × 1.2 m bed made from 50 mm sleepers, the inside is about 2.3 × 1.1 m. Filled to just below the top of a 400 mm bed (say 380 mm):
2.3 × 1.1 × 0.38 ≈ 0.96 m³
Garden soil is usually sold by the cubic metre. For deep beds, you can fill the bottom third with coarse organic material (branches, straw, old leaves) to cut the cost — it breaks down over time, so top up the soil after the first season.
Is treated pine safe for a vegetable garden?
For edible gardens, Bunnings recommends H4 timber treated with MicroPro, a copper-based treatment, rather than CCA (copper chrome arsenate). The Timber Preservers Association says studies show CCA isn’t taken up into crops like tomatoes, but root vegetables can pick up small amounts, mostly removed by peeling. The simplest approach:
- choose H4 timber with a copper-based treatment (MicroPro, ACQ or copper azole), or
- line the inside walls with plastic if you’re reusing older CCA timber.
Build steps in brief
- Level the site and mark out the bed.
- Cut the end sleepers and corner posts.
- Paint the in-ground ends of the posts with bitumen.
- Screw the first course to the corner posts, check it’s square (the diagonals should match) and level.
- Stack and screw the next courses, staggering joins if you’re using several lengths.
- Line the inside walls, then fill.
Sources
Every rule on this page is taken from these official sources. If a rule has changed, please tell us and we’ll fix it.
This guide is general information, not legal or professional advice. Rules differ between states, councils and individual properties, and they change. Confirm with your state regulator or council before starting work, and if in doubt, get a licensed tradesperson.