Build a Window Seat With IKEA BESTA Cabinets in 8 Steps

Why two 60cm BESTA frames and not one long one

Start with the geometry, because it decides everything after. A BESTA frame in the 60x42x38cm size sits at 38cm tall. Put a 64mm seat cushion on top and you land near 44cm, which is close to a dining chair and comfortable for most adults. Two of those frames butted together give you 120cm of bench. People reach for the single 120cm frame to save a joint, and then find it has flexed in transit and the back panel bows. Two short frames track straighter and let you run a fixing into a stud at each end.

Depth is the other call. The 42cm deep frame leaves room for a cushion plus a few centimetres of overhang at the front, so the back of your knees clear the edge. Go to the 20cm deep frame and you get a shallow ledge nobody wants to sit on for long. If your window reveal is deeper than 42cm you can pack the gap behind with a timber batten and a ripped board, which also gives you a solid line to screw the worktop down into later.

Set the cabinets dead level before you touch a screw

BESTA frames ship with adjustable feet, but those feet are meant for a wardrobe standing free, not a bench taking 90kg of bounce. Pull the feet, or wind them right in, and instead build a plinth from 18mm plywood or a doubled 38x63mm softwood frame. The plinth does two jobs: it sets the toe-kick recess at the front so your heels do not knock the doors, and it gives you a rigid base to shim level on an old uneven floor.

Get a 1200mm spirit level across the top of both frames once they sit on the plinth. A 3mm dip over that span shows up the second you lay a flat worktop and the joint between the two frames opens. Pack under the plinth with plastic packers, the tapered kind plumbers use, and snap off the tails. Check level along the length, then across the depth, then diagonally. Old houses near a window often have a floor that drops toward the external wall by 8 to 10mm over half a metre, so expect to shim the front edge up.

Butt the two frames tight and join them through the side panels with the BESTA connection bolts, or with two 4x35mm screws top and bottom if you have lost the IKEA hardware. A continuous front face matters more here than it does in a wardrobe, because the worktop telegraphs any step between frames.

Fixing into the wall: this is where most benches fail

A window seat gets sat on, climbed on, and used as a step stool by a child reaching the latch. The back of the cabinet has to be tied to the wall or the whole thing walks forward over a year. What you screw into changes the whole approach.

Into a timber stud wall: find the studs with a detector, mark them, and drive 6x80mm wood screws through the cabinet back rail into solid timber. Two per frame, staggered high and low. The 12mm chipboard back panel that comes with BESTA carries nothing, so the screw has to pass through it and bite the framing batten you have added, or the stud directly.

Into solid masonry, brick or block: drill with a 7mm masonry bit, blow the dust out, and use a proper frame fixing or a nylon plug rated for the load, not the grey plastic plugs in the bottom of the toolbox. Brown 7x50mm plugs with a 5x70mm screw hold fine. The dust matters. A hole full of brick dust halves the grip, so a few pumps with a blow pump or even a drinking straw makes the difference.

Into plasterboard with no stud where you need one: this is the case that catches people. You cannot rely on a spring toggle alone for a seat. Add a horizontal timber batten, 38x38mm, screwed across two studs first, then fix the cabinet to that batten. If you genuinely have nothing behind the board, heavy-duty steel toggle anchors rated above 30kg each, spaced four across, will hold the back from tipping, but they will never feel as solid as timber. The forces on a seat back are mostly horizontal pull-out, which is the exact load cheap wall anchors are worst at.

Run a bead of decorator caulk along the back top edge before you push it to the wall, and the gap disappears even if the plaster is wavy.

The worktop, the bit people skip

Lay an 18mm or 28mm worktop over the two frames and screw down from underneath through the frame top rails with 4x30mm screws. Go through from below so no screw head shows on the seat. A 28mm laminate kitchen worktop offcut is the cheap route and takes a beating. Solid oak looks better and costs more, and it will cup near a sunny window unless you oil both faces. Cut the worktop 10 to 15mm proud of the cabinet front so the cushion edge sits over a slight overhang, and ease that front edge with 120 grit so a bare leg does not catch a sharp arris.

If the seat sits in a window reveal between two walls, cut the worktop 4mm shy on each end and fill the line with caulk. A worktop cut to a tight 0mm fit will jam and scuff the paint going in, and you will never get it back out to access the cabinet. Scribe the back edge to the wall if the plaster is bellied, using a compass and a jigsaw, otherwise that back gap stares at you every time you sit down.

Cushion and finish

A 50 to 64mm high-density foam, 35kg per cubic metre or denser, holds its shape under daily use where cheap reflex foam flattens in months. Get it cut 5mm under the worktop size all round so the cover does not bulge at the corners. A piece of Farrow and Ball in a muted tone on the cabinet doors lifts a plain white BESTA out of flat-pack territory, and an eggshell finish wipes clean where a chalky matt marks.

Lighting the seat for reading

An Anglepoise wall lamp mounted 1.4m off the floor and offset 30cm to one side throws light over the shoulder without glare on a book. Fix its bracket into a stud or a fixing plate, not the plasterboard alone, because the sprung arm puts a constant turning load on the screws.

Doors, drawers and the access problem

Hinged BESTA doors swing out into the room and need clear floor in front. In a tight bay that is fine, since you stand back to sit anyway. Drawers are the better answer for a window seat because you pull them toward you from a standing position, and you are not bending into a dark cabinet. The 60cm BESTA drawer runs on push-open or soft-close runners rated to around 15kg loaded, which suits books, board games and spare bedding.

Watch the worktop overhang against drawer travel. If your worktop sits 15mm proud at the front and the drawer front is flush with the cabinet, the drawer clears easily. But fit BESTA drawer fronts that themselves stand proud, and the worktop lip fouls them on opening. Mock it up with the drawer in before you screw the worktop down for good. Set the soft-close so a full drawer does not slam, because a 15kg drawer of books closing hard will, over time, loosen the runner screws in the chipboard side panel.

Leave one frame as open shelving with no door at all if the seat lives in a hallway and you want a spot for shoes that air out. The internal BESTA shelf clips into the same pre-drilled holes whether or not a door is fitted.

The one question worth sitting with before you cut anything: is your window reveal square, or does it splay wider at the top than the bottom? A splayed reveal means the worktop that fits the base will leave a wedge gap at one end up high, and no amount of caulk hides a tapered line at eye level.