Trending
Scaffold boards are one of the best-kept secrets of garden woodworking. They are cheap, thick, and already cut to a sensible length, and they were made to be left outside in the rain. That makes them ideal for a bench you actually want to sit on rather than one you are afraid to leave out. This build uses five boards and a handful of screws. It is not fussy joinery and it does not need a workshop full of tools, but the result is a bench that will hold two adults without a creak.
The whole job takes an afternoon, plus time for the finish to dry. If you can measure, saw in a straight line and drive a screw without splitting the timber, you can do this.
Standard scaffold boards in the UK are usually 225mm wide, 38mm thick, and sold in 2.4m or 3.9m lengths. Banded, kiln-dried boards are the ones to ask for, as reclaimed boards from a scaffold yard are often soaked, cracked or covered in concrete. Two 2.4m boards will give you a bench roughly 1.5m long with material left over.
For this design you need:
Tools: a circular saw or handsaw, a drill, a tape measure, a square, a pencil, a rasp and a couple of clamps. A random orbital sander saves an hour of elbow grease and is worth borrowing if you do not own one.
Dimensions are yours to adjust, but these proportions work well for a bench that seats two comfortably. Seat height matters most: 450mm is a good target, measured from the ground to the top of the seat slats. Any lower and it is awkward to stand up from; any higher and shorter guests will dangle.
Cut three boards to 1500mm for the seat. There should be a small gap between each slat, around 5mm, so water drains instead of pooling. Cut two boards to 1500mm for the backrest, which sits above the seat at a slight angle. If you prefer a flat back, that is fine, but a rake of about 10 degrees is far more comfortable to lean against.
Cut four legs to 420mm, which gives you 450mm once the 30mm seat slats are fixed on top, allowing for a little trimming. Cut two rails at 400mm for the front and back of the frame, and two side rails at 400mm to tie the front and rear legs together. Mark your boards with a pencil before cutting, and check twice. Scaffold board is thick enough that a saw will wander if you rush, so let the blade do the work and keep the offcut supported.
Sand every board now, not after assembly. The awkward inside corners are much easier to reach while the timber is flat on the trestles. Start with 80 grit to flatten any saw marks and plane ripple, move to 120 to remove the scratches from the coarse paper, and finish with 180. Break the sharp edges along every length with a light pass, then run a rasp over the cut ends so nobody catches a hand on them.
Scaffold board is softwood, usually spruce or pine, and it dents easily. Sand with the grain, keep the sander moving, and do not press down hard. If the boards have a green tint from the treatment, that is normal and will fade; it does not stop the finish from taking.
Work on a flat surface. Fix the front and back rails between the pairs of legs, with the rails set back from the front face of the legs so the screw heads are not where knees go. Drill pilot holes first, especially near the ends of rails where softwood loves to split. Two screws per joint is plenty.
Stand the two leg frames up and connect them with the side rails. Check for square by measuring diagonally from corner to corner in both directions; the two measurements should match. If they do not, rack the frame gently until they do, then screw the side rails home.
Now sit the three seat slats across the frame and space them evenly. Centre the outer slats so they overhang the frame slightly at the front and back. Screw down through the slats into the rails, countersinking the heads just below the surface. Two screws per slat per rail is enough; more holes just give water somewhere to sit.
Attach two upright supports to the rear legs, set at roughly 10 degrees from vertical. The simplest way is to cut the bottoms of the uprights at an angle so they sit flat on the legs, then screw through the leg into the upright from behind, or use a short bracket. Fix the two backrest slats to these uprights, leaving a 20mm gap so the bench does not look like a solid wall.
Lean on the finished back before you commit to the height. It should catch you just below the shoulder blades when you sit. Move it if it does not, because you will notice it every time you use the bench.
Untreated softwood left outside will grey and eventually split. Give the bench two or three coats of an exterior wood oil or a coloured wood stain, applied with a brush and wiped back where it pools. Oil soaks in and needs refreshing every year or two; stain and paint build a film that lasts longer but will need sanding back when it flakes. Slightly raise the bench on small feet or blocks so the legs are not standing in damp grass, and the base of the legs will last far longer.
Do not seal the underside of the seat slats completely. Wood needs to move with the seasons, and trapping moisture is what turns a good bench into a rotten one.
Scaffold boards are heavy, so build on trestles at a comfortable height rather than on the ground. If you are cutting with a circular saw, clamp the board and let the offcut hang free on the side you are not standing on, so the blade is not pinched. Wear eye protection and a dust mask, particularly when sanding treated timber.
Once built, the bench needs almost nothing: a wipe down and a fresh coat of oil each spring. If you want to soften it further, a cushion on the seat costs little and hides the knots. Keep the design simple, keep the joints tight, and this is the sort of bench that stays in a garden for fifteen years.
