How to Build a Raised Bed with Sleepers or Scaffold Boards

To build a sleeper raised bed, level the ground and lay the first course of sleepers on edge in a rectangle no wider than 1.2 m. Stack a second course with the corners overlapped like brickwork, and fix the courses together with long structural timber screws or galvanised corner brackets. For vegetables, use new UC4-treated or hardwood sleepers rather than reclaimed creosote sleepers. Fill with a 60:40 mix of topsoil and compost.

Raised beds are the easiest way to grow vegetables, fruit and flowers on poor soil, a slope or a patio. They warm up earlier in spring, drain well, and save your back. Railway sleepers and scaffold boards are two of the most popular materials because they are strong, simple to work with and look good for years.

This guide shows you how to build both, how many you need, and which timber is safe for growing food.

Sleepers or scaffold boards: which is better for a raised bed?

If you want a bed that lasts and doubles as a seat, choose sleepers. If you want lots of beds on a budget, scaffold boards go further.

Which sleepers are safe for vegetable raised beds?

This is the question we hear most at the yard.

• New UC4-treated softwood sleepers are pressure-treated with modern preservatives for ground contact. They are widely used for vegetable beds. For extra peace of mind, line the inside walls with a heavy-duty polythene or pond liner, leaving the base open for drainage. See our UC4 treated sleepers.

• New hardwood sleepers such as L.Oak are naturally durable and need no chemical treatment for this use.

• Reclaimed railway sleepers were treated with creosote. Rules on creosote-treated wood say it should not be used where it is in frequent skin contact or in contact with food crops. Use reclaimed sleepers for flower beds, shrub borders and retaining edges, not for vegetables.

• UC3 sleepers are rated for above-ground use. In a bed full of damp soil they will rot sooner. Our UC3 vs UC4 guide explains the difference.

The best size for a raised bed

• Width: no more than 1.2 m if you can reach it from both sides, or 600–750 mm if it sits against a fence or wall. You should be able to reach the middle without stepping on the soil.

• Length: any length, but 2.4 m suits a standard new sleeper with no cutting on the long sides.

• Height: 300–450 mm is enough for most vegetables. Go to 600–750 mm for easier access if you have back or knee problems, or for wheelchair users.

• Paths: leave at least 450 mm between beds, or 900 mm for a wheelbarrow. Decorative chippings or gravel make paths that stay weed-free and dry underfoot.

How many sleepers do I need?

Here are three common beds using new 2,400 × 200 × 100 mm sleepers laid on edge:

For reclaimed 2,600 × 250 × 150 mm sleepers, two courses give a 500 mm high bed. We can cut sleepers to length before delivery, so they arrive ready to assemble.

How much soil? Multiply the inside length × width × height. A 2.4 × 1.2 m bed, 400 mm high, holds just under 1 m³ of soil once you allow for the thickness of the sleepers.

Tools and materials

• Sleepers or scaffold boards

• Structural timber screws, 200–250 mm, for joining sleeper courses

• Galvanised sleeper corner brackets (optional but quick)

• For scaffold boards: timber posts for the corners and exterior timber screws about 70 mm long

• Spirit level, tape measure, spade, rubber mallet, impact driver

• Weed-suppressing membrane or cardboard for the base, and a liner for the sides if growing food

• Topsoil and compost

How to build a sleeper raised bed in 7 steps

1. Pick the spot. Choose a level, sunny site with at least 6 hours of sun for vegetables. Avoid low spots where water collects.

2. Mark and level the ground. Peg out the rectangle and check the diagonals are equal so the corners are square. Remove turf and level the strip where the first course will sit. On a slope, dig the first sleeper into the high side so it sits level.

3. Lay the first course. Set the sleepers on edge, butting the ends against the sides of the long sleepers. Check every sleeper with a spirit level. This course decides how straight the whole bed is.

4. Lay the second course, overlapping the corners. Turn the corner joints the other way on each course, like bricks, so every corner is locked together.

5. Fix the courses together. Drive two structural timber screws down through each sleeper into the one below, near each end. At the corners, add a screw through the side, or fit a galvanised corner bracket on the inside.

6. Line and base the bed. Staple a liner to the inside walls if you are growing vegetables. Lay cardboard or a permeable membrane on the base to smother weeds. Do not use a waterproof sheet on the base, as the bed needs to drain.

7. Fill the bed. Start with coarse organic material (prunings, leaves, turf turned upside down) in deep beds. Top with a 60:40 mix of topsoil and compost, and settle it with water before planting. Top up with compost each spring.

How to build a scaffold board raised bed

Scaffold boards are only 38 mm thick, so they need corner posts to stay square once the soil goes in.

1. Cut the boards. A 3.9 m board cut in half gives two 1.95 m long sides. Four 0.9 m end pieces come from one board. Our new untreated unbanded scaffold boards suit flower beds; brown pressure-treated boards last longer in soil.

2. Cut four corner posts to the bed height plus 200 mm to push into the ground.

3. Build two ends first. Screw the end boards to two posts, keeping the bottom of the posts sticking out 200 mm.

4. Add the long sides. Stand the ends up, drive the posts in, and screw the long boards on. Use two screws per board at every post.

5. Add a mid post on any side longer than 2 m to stop it bowing outwards.

6. Line, base and fill as for a sleeper bed.

A 1.95 × 0.9 m bed, three boards high (about 675 mm), needs 5 scaffold boards and 4 posts. Browse our full range of scaffold boards.

Building a raised bed against a fence or wall

• Leave a gap of at least 50 mm between the bed and the fence so soil never touches the panels. Wet soil against a fence rots it quickly, and it may be your neighbour’s fence.

• Build a full four-sided bed rather than using the fence as the back.

• Keep beds against a fence to 600–750 mm wide, so you can reach the back.

Raised sleeper bed ideas

• Seating edge: cap a 450 mm bed with a flat sleeper to make a bench. Use new sleepers here, not reclaimed.

• Tiered beds: stack a smaller bed on top of a larger one for herbs and trailing plants.

• L-shaped and U-shaped beds: wrap around a patio for an enclosed, sheltered growing area.

• Terraced beds on a slope: each bed holds back the one above. For banks over 1 m, see our guide to building a sleeper retaining wall.

• Planter beds: half whiskey barrels at the corners add height and colour.

For more designs, see 5 railway sleeper garden ideas.

Sleeper raised bed kit or loose sleepers?

Kits come pre-cut with brackets, so they are quick to assemble. Loose sleepers usually cost less per metre, let you choose any size, and are thicker and stronger than many kit timbers. With our cutting service, loose sleepers can arrive cut to your exact sizes, which gives you the best of both.

Frequently asked questions

Are railway sleepers safe for vegetable gardens? New UC4-treated and new hardwood sleepers are widely used for vegetable beds; lining the inside walls adds extra protection. Reclaimed creosote-treated sleepers should not be used for growing food.

Do I need to line a sleeper raised bed? Lining the sides is recommended for vegetables and helps the timber last longer. Leave the base open, or use a permeable membrane, so water can drain.

How deep should a raised bed be? 300–450 mm suits most vegetables. Root crops such as carrots and parsnips do best with 400 mm or more.

Do sleeper raised beds need posts? Sleeper beds up to three courses high do not need posts if the courses are screwed together and the corners overlapped. Scaffold board beds always need corner posts.

How long does a sleeper raised bed last? A bed made from UC4-treated sleepers lasts around 15–20 years. Hardwood and reclaimed oak sleepers can last longer. Treated scaffold boards last around 10–15 years.

What do I put in the bottom of a raised bed? Cardboard or a permeable weed membrane, then coarse organic material in deep beds, then a 60:40 mix of topsoil and compost.

Order your raised bed timber

Davids Timber supplies new railway sleepers, UC4-treated sleepers, reclaimed sleepers and scaffold boards from its yards in Heath and Reach, Bedfordshire, and Brigg, North Lincolnshire. We deliver across the UK and cut to length on request. Call 0800 102 6450 and we will help you work out exactly what your bed needs.