How to Build a Simple Garden Bench - UK DIY Guide

A garden bench is one of those projects that looks harder than it actually is. You see them in garden centres for £150-£300, and they're almost always made from softwood that'll start splitting within two British winters. Build your own and you get three things: a bench built to last, a satisfying weekend project, and the knowledge that you saved yourself a chunk of money.

This guide walks through building a simple three-seat garden bench from pressure-treated timber. It's designed for someone with basic tool experience - if you've used a drill and a jigsaw before, you've already got the skills you need.

Tools You'll Need

You do not need a full workshop for this project. Here's what actually gets used:

Power Tools

Cordless Drill - This is your main tool. You'll use it to drill pilot holes and drive screws. A mid-range 18V cordless drill like the DeWalt DCD778S2T has more than enough torque for exterior screws, and the battery will last the whole build. Read our best cordless drills guide for other options.

Jigsaw - For cutting the timber to length and shaping the armrests. A corded jigsaw like the DeWalt DCS334N-XJ with a medium-tooth wood blade makes clean cuts through 50mm timber. See our best jigsaw review for cordless alternatives.

Random Orbital Sander - Not essential, but makes a huge difference to the finish. Sanding the seat boards and armrests removes splinters and gives a surface that accepts wood preserver properly. The DeWalt DWE6423 with 120-grit discs does the job fast. Check our orbital sander guide for more.

Hand Tools & Accessories

• 5m Tape Measure - The OX Trade 5m has a wide 25mm blade that stays rigid for 2m, making solo measuring much easier
• 60cm Spirit Level - Bosch Professional level for checking the bench sits level on uneven ground
• Safety Glasses - NoCry goggles with anti-fog coating. Wear them when cutting, sanding, or driving screws
• Pencil & Carpenter's Square - For marking cut lines. Any 2B pencil works
• Clamps - A couple of quick-release clamps hold timber steady while cutting or drilling
• Workbench or Sawhorses - The WORX Pegasus folding workbench makes an excellent portable cutting station. See our workbench review for alternatives

Materials You'll Need

All timber is available from any UK builders merchant or DIY chain. Pressure-treated softwood (usually 'tanalised' or 'UC4 treated') is ideal for outdoor use - it'll resist rot and insect damage for years. Suggested dimensions: 1200mm wide x 450mm deep x 450mm high - comfortable for two people or three at a squeeze.

Total timber cost: roughly £40-£60 depending on your local merchant. I'd recommend buying a couple of extra boards in case of measurement mistakes - you will cut something wrong on your first build.

Fixings & Finishing

• Exterior Wood Screws 6x60mm - Forgefix Pozi drive, box of 100. The 6mm diameter gives proper holding power in softwood, and the Pozi head reduces cam-out with a power driver. The green coating is corrosion-resistant for outdoor use.
• Outdoor Wood Preserver - Furniture Clinic 5L clear preserver. Apply before assembly for best coverage, then a second coat after assembly. One 5L tin covers this bench with some left over.
• Wood Paint or Stain - Optional. Cuprinol Garden Shades in Black Ash gives a smart charcoal finish that hides dirt. If you prefer natural wood, skip the paint and use a UV-protective oil instead.
• Sandpaper Discs 125mm (80 & 120 Grit) - SATC 72-pack covers all grits you'll need. Start with 80 grit to remove rough-sawn texture, finish with 120 grit for a smooth surface.

Step-by-Step Build

Step 1: Cut all timber to size

Using your jigsaw with a medium-tooth wood blade, cut all boards to the lengths in the cutting list above. Mark each piece with a pencil as you go - it's easy to mix up leg uprights and backrest supports when they're similar sizes. The OX tape measure with its wide blade makes solo measuring much easier because the blade stays rigid for 2m without flopping over. Use a carpenter's square to mark square cut lines every time - wonky cuts mean wobbly joints.

Tip: If you're using a folding workbench, clamp the timber down before cutting. The Worx Pegasus is great for this because its bench-top clamps hold boards securely without needing a separate clamp for every cut.

Step 2: Sand everything

Before assembly, sand all surfaces that will be visible or touched - especially the seat boards and armrests. Attach 80-grit discs to your orbital sander for the first pass to knock off the rough-sawn texture, then switch to 120 grit for a smooth finish. Pay extra attention to edges and corners where splinters love to hide. If you don't own a sander, wrap sandpaper around a cork block and do it by hand - it'll take longer but the result is the same.

Step 3: Build the side frames

Each side frame consists of two leg uprights (450mm) joined by an apron (400mm) at the top and a backrest support (400mm) at the back. Lay the pieces flat on your work surface. Drill 3mm pilot holes through the apron into the leg tops, then drive 6x60mm exterior screws through the pilot holes using your cordless drill.

Repeat for the backrest support into the back legs. The Forgefix screws have a sharp self-tapping point and the Pozi drive stays engaged with the drill bit even at high torque - fewer stripped heads than standard cross-head screws.

Use your spirit level to check each joint is square before driving screws fully home. A 1-degree error in the first frame doubles by the time you add the seat boards. Build both side frames exactly the same way.

Step 4: Attach the seat boards

Lay the four seat boards (1200mm) across the two side frames, spaced evenly with a 5-6mm gap between each board for water drainage and wood movement. Drill pilot holes through the seat boards into the aprons below and secure with two screws per board per side - 16 screws total. Make sure the boards overhang equally on each side for a balanced look.

Step 5: Attach the backrest boards

Position the three backrest boards (1200mm) against the backrest supports, again with small drainage gaps. The bottom backrest board should sit about 150mm above the seat to leave room for cushions if you want them later. Drill and screw through the boards into the supports.

Step 6: Fit the cross brace

The cross brace (1100mm) runs between the two side frames underneath the seat, about halfway down the legs. This stops the bench from racking (wobbling side to side) and makes a huge difference to the overall stiffness. Pre-drill and screw through each end into the inside face of the leg uprights.

Step 7: Add the armrests

If you want armrests, attach a small support block (200mm) to each side frame at seat height, then screw the armrest board (500mm) on top. Round the front corners of the armrests with your jigsaw for a more comfortable feel and a professional look. Sand the cut edges smooth.

Step 8: Final assembly & finishing

Turn the bench upright and check it sits level on your floor. Tighten any loose screws. If anything rocks, shim the shortest leg with a felt pad or thin offcut rather than recutting - it's hidden underneath and nobody will see it.

Apply wood preserver to all surfaces, especially end-grain cuts which absorb water fastest. A brush works better than a roller for getting into the gaps between boards. Let the first coat dry for 4-6 hours, then apply a second coat. If you're painting, apply the Cuprinol Garden Shades after the preserver has cured - it'll last longer with the preserver as a base layer.

Frequently Asked Questions

Products Mentioned in This Guide

Final Verdict

Building your own garden bench is one of those projects that keeps giving. You get a weekend of making, a solid piece of garden furniture that'll last years, and that quiet satisfaction every time someone sits on it and says "you built this?"

The total bill - around £80-£110 for materials and finishing if you already have a drill and jigsaw - beats anything you can buy at that price point. Most garden centre benches at £150 are made from thinner timber with rusty-looking staples holding the joints together. This one uses 6mm screws into every joint, with proper preservative treatment that'll keep it solid through British weather.

If you've never built outdoor furniture before, this is the perfect first project. Simple lines, forgiving tolerances, and the kind of result you'll actually use every day. Give it a go - you've got nothing to lose but a few hours on a Saturday.

J

James Walker

James Walker writes about power tools, hand tools and workshop setup for MakerUK.

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Last reviewed: July 27, 2026 · Evidence-based content · Contains affiliate links