How to Build a Raised Bed — Step-by-Step UK Guide

What You'll Need

Before You Start

• Choose a level spot with good sunlight — most vegetables need 6+ hours of direct sun.
• Decide on dimensions. A maximum width of 1.2m lets you reach the centre from either side. Length can be anything, but 1.8m or 2.4m uses standard sleeper lengths efficiently.
• Calculate your soil volume using our Raised Bed Soil Calculator and order topsoil with our Topsoil Calculator.
• Check for underground services before digging any fixing stakes into the ground.

Step-by-Step Instructions

Step 1: Prepare the Ground

Remove turf or weeds from the bed area. If the ground is compacted, fork it over to improve drainage. Level the area using a spirit level and rake. You do not need to excavate — the bed sits on the existing ground level.

Step 2: Cut the Sleepers

Cut sleepers to length. For a 2.4m x 1.2m bed, you need two 2.4m lengths and two 1.2m lengths per course. If stacking two courses high (400mm), double the quantities. Cut with a circular saw — these are thick timbers, so you may need to cut from both sides.

Step 3: Lay the First Course

Position the first course of sleepers on the prepared ground. Check they are level in all directions — use a rubber mallet to adjust and pack underneath with sand if needed. Check the corners are square by measuring diagonals.

Step 4: Fix the Corners

For a single-course bed, use galvanised angle brackets at each internal corner. For multi-course beds, overlap the sleepers at the corners (like a log cabin) and fix with M10 x 200mm coach screws — pre-drill pilot holes first. Drive rebar stakes (12mm) through the sleepers into the ground at each corner and every 1.2m along the length for added stability.

Step 5: Add Additional Courses

Stack the second course with joints offset from the first (staggered bond). Fix each course to the one below using coach screws at 600mm centres. Check levels after each course.

Step 6: Line the Inside

If using treated timber, staple heavy-duty polythene (DPM) to the inside faces. Overlap sheets by 150mm. Do not line the base — water must drain through. For deep beds, add a 50mm layer of coarse gravel or broken crocks at the bottom.

Step 7: Fill with Soil

Fill with a mix of 60% topsoil, 30% well-rotted compost and 10% perlite or sharp sand. Fill in 150mm layers, gently firming each layer. Fill to 25mm below the rim — the soil will settle over the first few weeks. Top up as needed.

Step 8: Water and Settle

Give the filled bed a thorough soaking to settle the soil. Top up any low spots after 24 hours. Allow a week before planting if possible.

Common Mistakes to Avoid

• Making it too wide: Over 1.2m wide and you cannot reach the centre comfortably. You end up stepping on the soil and compacting it.
• Skipping the levelling: An unlevel bed looks wrong and water pools at the low end instead of draining evenly.
• Using 100% topsoil: Pure topsoil compacts and becomes waterlogged. Always mix in compost and something for drainage.
• Forgetting drainage: If building on clay soil or a paved surface, a gravel layer at the bottom is essential to prevent waterlogging.
• Using unsuitable timber: Untreated softwood rots within 2-3 years. Use UC4 treated timber, oak, or composite materials.

Cost Estimate (2026 UK Prices)

Use our Raised Bed Soil Calculator and Topsoil Calculator for exact fill quantities.