Guide
Why your plan has parts you would not find in a shop-bought version
If you have assembled a flat-pack wardrobe or bookcase, your build plan may contain a piece you did not expect: a rail under the top panel, a vertical divider, a batten screwed to the wall. It is a fair question to ask why a factory manages without them. The answer is not that the plan is over-engineered. It is that a factory and a workshop solve the same problem with different tools, and one of the things you get in exchange is a piece of furniture that is the size of your wall rather than the nearest standard size.
Figures for France in 18 mm boards. Your country may stock different thicknesses, and the builder recomputes the parts for the boards yours sells.
The trade you are making
A furniture factory has three things a home workshop does not: machines that hold a tolerance you cannot hold by hand, materials chosen and tested in bulk, and the freedom to sell you only the sizes it has decided to make.
That last one matters more than it sounds. A wardrobe system comes in a handful of frame widths and two heights. Your alcove is not one of those sizes, so you fit the room to the furniture: a filler strip here, a gap there, a run that stops short of the corner.
A plan built to your measurements does the opposite. It fits the wall you actually have. The parts below are what that costs, and they are cheaper than the alternative in every sense except the number of pieces you cut.
The reinforcement rail (wardrobes)
What the industry does. Flat-pack wardrobe frames stop at about a metre wide, and their hanging rod is metal. A wider wardrobe is several frames bolted together, each with its own rod. A metal rod is considerably stiffer than a wooden one of the same size, so at a metre it needs no support at all.
What we do. Your rod is a wooden dowel, and your wardrobe is as wide as you asked for. A wooden rod holds about 61 cm before it sags noticeably, so a wider one needs a support in the middle, and that support needs something solid to hang from. That is the rail: a board fitted on edge under the top, its ends screwed through the side panels.
Why. A wooden rod is cut to length with the same saw as the rest of the build, and shortened on site if the wall turns out not to be square. A metal one comes in fixed lengths and needs a different tool and a different set of end fittings. Fitting the rail on edge rather than flat makes it far stiffer for the same board, which is why a strip a few centimetres tall does the work of a full-height panel: in MDF at a metre wide it is 13 cm, in plywood only 7.
And you can avoid it. If you would rather not build the rail, build several narrower wardrobes instead: each rod is then short enough to need nothing.
One wide wardrobe, or several narrow ones? The numbers on both
The centre divider (shelving)
What the industry does. A shop bookcase is about 80 cm wide, and that is not an accident: it is roughly as far as a shelf of that material spans before it sags. Wider models exist, and they have a divider too, or a thicker shelf, or a metal support strip along the back.
What we do. You choose the width. If the shelf you asked for would sag past the limit over that span, the plan adds a vertical divider to halve it.
Why. Sag goes up with the cube of the span: double the width and the shelf sags eight times as much. A divider in the middle is the cheapest possible fix, and it is one board.
And it depends on the material. A plywood shelf spans much further than an MDF one, so the same wardrobe can need a divider in one material and none in another. If a divider is in your way, changing material may remove it.
The wall battens (alcove units)
What the industry does. A shop alcove unit is a free-standing box pushed into the recess, with a gap on each side hidden by trim. Its shelves rest on pegs in its own sides.
What we do. There is no box. The shelves rest on battens screwed to the three walls of the recess.
Why. An alcove is never square, never plumb and rarely the same width top and bottom. A box built to the narrowest measurement leaves a gap at the widest; a box built to the widest does not go in. Battens follow the walls as they are. And a shelf supported on three sides carries considerably more than the same shelf held at two ends, which is why an alcove unit needs no divider where a free-standing one would.
The bevelled cleats (under-slope units)
What the industry does. Furniture for a sloping ceiling is mostly sold as a rectangular box that stops below the slope, wasting the triangle above it, or as a bespoke fitted job.
What we do. The unit follows the roof line, so the top panel lies at the angle of your ceiling and rests on cleats cut to the same angle.
Why. The cleats are what let a panel meet a sloping surface across its whole face rather than along one edge. Cutting them at the roof angle is the difference between a top panel that sits flat and one that rocks on a line.
And the angle is yours, not a standard one. This is the clearest case of the whole page: nobody sells furniture for your particular roof pitch, because there is no such thing as a standard roof pitch.
How to plan a unit for a sloping ceiling
How to cut a bevel, and which of them you can skip
What you get for it
Put together, the pattern is the same each time. The industry removes a part by removing a choice: a fixed width, a fixed height, a metal component, a standard angle. A plan made to your measurements keeps the choice and pays for it with a part.
The parts are cheap. A rail is a strip off a board you have already bought. A divider is one panel. Battens are offcuts. What they buy is a piece of furniture with no filler strips, no gap against the wall, and no wasted triangle under the roof.
In Kamba
Every part in your cut list is derived from your own measurements and materials, never added by default. If a part appears, the plan says which number put it there, and where a choice would remove it, the plan says that too.
See standard shelf dimensions and safe spans
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