Ladder Shelving Unit – Assembling the shelves & the ladder

Some projects are simple to design and to build. Others pose challenges that require a modicum of lateral thinking, and this commission is a perfect example of that. Solving the problems at the design stage led to a neat solution that delivered good looks and practical performance without breaching the budget

Ladder Shelving Unit Photo 02

This project started life when I was asked to make a small storage unit to fit into one corner of a small pantry. The job seemed straightforward enough, until I discovered that there was a socket directly in line with the side panel of the unit. It wasn’t going to be practical to move the socket, so the cupboard had to accommodate it. However, it wasn’t going to be a neat job if I cut a hole in the unit for the plug and socket, especially as the hole would need to be big enough for the plug to be removed.

Ladder Shelving Unit Photo 01This ruled out a conventional box-sided unit; what I needed was a design with open sides and back. I had made a ladder-style unit some months earlier for a customer who wanted some shelving to fit over some boxed-in pipework, photo 1, and this seemed to offer the best solution.

Design elements for Ladder Shelving Unit

The pantry is small, and to make the unit less obtrusive, it was to have a deep shelf at the bottom and the rest of the shelves reducing in depth towards the top. I designed the unit similarly to a staircase or ladder so the back and part of the sides could remain open.

It has sloping sides supporting open shelves which are made more practical (and stronger) by fitting an upstand to the sides and back of each shelf. The sides and shelves are made from 18mm moisture-resistant mdf, and the upstands from similar 12mm material.

Awkward angles

Construction of a unit like this is relatively easy, but working out the required angles can be tricky. Rather than attempting to calculate the sizes and angles, I drew the unit out using TurboCad on my computer and took my measurements directly from the drawings.

For the two uprights I took measurements from the drawings to work out the offsets. This is a lot easier, and more accurate, than trying to mark out a 4.1° cutting angle!

Ladder Shelving Unit Figure (Detail top & bottom)

Direct marking

From the drawing I made a cutting list for all the parts. There are computer programmes such as Cutlist which will work out the most effective layout to get the most from sheet material, but I usually just draw them out on the board. With the board marked out, remembering to leave at least 3-4mm between adjacent pieces for the saw kerf, I cut out the various parts using a circular saw and guide rail.

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It’s important that all the shelves have an identical width and are perfectly square; I actually cut all the parts slightly oversize and then trimmed them on the table saw to make sure.

Cutting corners

Preparing the two 150mm wide uprights was more awkward, and involved quite a few steps. First I cut them square to length at 1914mm. For the bottom angle I marked 11mm up from one corner and marked off the angled cutting line, photo 2. For the top angle, I marked 9mm down from the top corner, 22mm in from the opposite corner and joined these together to give the horizontal cutting line. I made a mark 303mm down the length and joined that to the mark at 22mm in from the edge to give me my vertical cutting line, photo 3. I then set the mitre saw to the correct angle and cut along the marked lines, photo 4; the longer cuts I had to do by hand.

Preparing the shelves

Next I cut a number of 50mm wide strips of 12mm mdf to form the upstands; as these are short lengths I managed to cut them from some mdf offcuts I had in stock.

All the edges on the unit will be rounded over. This looks better than a square edge, and a rounded edge will also take paint very much better. I set a 4.75mm radius roundover cutter in the table-mounted
router and rounded over both sides of one long edge on each shelf, photo 5.

Preparing the shelves for Ladder Photos

I cut nine lengths of the upstand to the width of the shelf, photo 6, to form the rear upstands, and then rounded over both sides of one long edge of each piece, photo 7.

Assembling the shelves

I applied PVA adhesive to the long square edge of each shelf, photo 8, and pinned the rear upstand in place, photo 9. I used an 18g brad nailer here for speed.

Assembling the shelves for Ladder Photos

The side upstands vary in size and need to be cut in pairs. I wanted their front edges to be rounded over slightly, so I fitted a 12.7mm radius roundover cutter in the table-mounted router and used a cross-cut fence to round them over, photo 10.

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I then refitted the smaller round-over cutter and rounded over the two edges adjacent to the rounded edge. I stopped the cutter short at both ends because a square edge is needed where the upstand abuts the shelf and rear upstand, photo 11.

These are then glued and pinned in place. Avoid placing pins where they will coincide with the positions of the biscuits that will fix the shelves to the sides later.

Coping with hiccups

I managed to round over too close to the corners in a couple of places, photo 12; these will need filling later. I also managed to split the mdf despite using the gun, photo 13; mdf can split so easily. To fix it, I put a generous amount of PVA along the crack and worked it well into the joint before cramping it overnight, photo 14.

Cleaning up

The shelves now needed a good clean-up before they were fitted into the frame. I used the small roundover cutter in a table-mounted router to round over the remaining accessible edges, and then it was out with the random orbit sander and an hour of dusty sanding to produce a stack of finished shelves, photo 15. The effort was well worth it, however; the final finish is so important with any mdf work.

A stack of finished shelves

Marking out the uprights

The sides now needed rounding over and cleaning up before I could mark out the biscuit locations and cut the slots. The biscuits are fitted along the centre line of the sides, following the angle of the bottom edge; I used a sliding bevel to mark the angle accurately, photo 16.

Measuring along an angled board can be difficult; you need to decide if you are going to measure along the ‘virtual’ vertical line or along the ‘actual’ edge. Marking along the edge is easier, but the measurements are slightly longer than the vertical distance between the shelves.

To mark a vertical line down the sides, I used a combination square set to half the width, photo 17, and marked a pencil line. I couldn’t use a marking gauge because it would have left a scored line down the board.

Positioning the biscuits

Cutting the biscuit slots in the sides meant aligning the biscuit jointer with the centre lines, photo 18, and checking that it didn’t move as it was plunged. I took accurate measurements off the diagram to work out exactly where the centre of each biscuit was for each shelf, and marked the centre line from the back edge of each shelf. I set the biscuit jointer to cut the joint 9mm from the edge and cut the slots. The centre line needs to project onto the top of the upstand, photo 19, so that the shelf can be accurately aligned with the sides, as biscuits do allow quite a bit of longitudinal movement.


Even though it should never be exposed to any moisture, there’s a good reason why I’ve used moisture-resistant mdf for the unit. It’s generally much denser and easier to finish than standard mdf, especially when compared to mdf from some of the large DIY stores, which can be frankly awful.

If you’re in any in doubt, look at the edges of the boards. They should have a crisp edge, and the core should be dense and hard. Always reject any boards which have a soft yet rough edge; it will be almost impossible to machine a clean edge on such boards.

Assembling the ladder

I applied plenty of glue to the biscuits and the slots, and also enough glue to fix the upstands to the sides for extra strength, photo 20. This all needed careful alignment and rigorous cramping while the glue cured, photo 21.

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Assembling the Ladder Shelving Unit (Photos)

Once the glue was dry, I gave the unit a final sanding and dusting, ready for finishing.

Painting mdf

I previously used a small foam roller to paint mdf, but I’ve now invested in a spray gun, which does make painting easier, especially on a relatively awkward-to-paint item like this. I gave it a coat of International’s mdf primer, then a coat of water-based primer, and finished it with two coats of quick-drying eggshell paint.

Although the unit is stable when it’s set to lean against the wall, especially when the shelves are loaded, I fitted a pair of metal brackets at the top and screwed it to the pantry wall for extra security.

This is a unit you can adapt in style and size to suit almost any storage need.

One comment

  1. Almena

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