Steel shelving is one of the most rewarding things to build yourself: simple structure, straightforward welding, mistakes rarely fatal. That simplicity is also why it usually gets built by eye — and why a year later the shelves bow and the whole rack wobbles. A few numbers worth settling first.
Start with the load, not the dimensions
Ask what will actually sit on a shelf. Boxes of hand tools and household odds and ends come to roughly 30–50 kg per shelf. Cases of fasteners, tins of paint, batteries — 80–120 kg. Wheels, bags of dry mix, heavy tooling — 150 kg and up.
Then the span. A shelf longer than a metre is a beam, and it is the span rather than the metal thickness that decides whether it sags. A 1.5 m span under 100 kg needs a stiffening rib or an intermediate upright; at 2 m there is no way around it.
What to build the frame from
- Square tube 40×40 or 40×20, 2 mm wall — the universal choice for garage shelving: 40×40 uprights, 40×20 rails.
- Angle 40×40×4 — the classic: cheaper, and the shelf board rests straight on the leg of the angle.
- Square tube 50×50 — when the load is genuinely heavy or the unit is over 2 m tall.
Shelf decks are 15–18 mm plywood, OSB, or 1.5–2 mm steel sheet with a folded edge. A 20–30 mm fold turns the sheet into a beam and removes almost all deflection — the same sheet without it visibly sags under the same weight.
Shelf spacing and depth
Typical spacing is 35–45 cm: a box or a bucket fits, without wasting half the usable volume. The bottom shelf sits 10–15 cm off the floor so you can clean underneath and it does not stand in meltwater.
A depth of 40–50 cm covers most needs. Deeper shelves look roomier but make it awkward to reach whatever is at the back — which is precisely where things vanish for years.
Welded or bolted
A welded rack is stiffer and faster to build, but it is monolithic: you can only move it whole, and repositioning a shelf means reaching for the grinder. Bolted joints give you a rack that comes apart and adjusts, but they need accurate holes — marking out by eye produces misalignment you cannot fix afterwards.
The practical compromise is welded side frames plus bolted rails: the frames hold the geometry and the shelves stay adjustable. Most warehouse shelving is built exactly this way.
Stability: why shelving is anchored
Tall, narrow shelving tips over — that is geometry, not weld quality. Once the height is more than three times the depth, anchoring to the wall is mandatory; two anchors at the top solve it entirely. A diagonal brace on the back is equally necessary, otherwise the frame folds into a parallelogram and the rack sways with every movement.
Put the heavy things at the bottom — for stability and for your back. The most common domestic mistake is batteries and paint on the top shelf, empty boxes below.
Corrosion protection
In a heated room, primer and any enamel will do. In a garage, cellar or unheated store the metal lives in condensation, and aerosol paint lasts a season or two. Powder coating gives an even polymer film that boxes do not scrape off and damp does not lift — which is why industrial shelving is finished that way.
What is easier to order
The longest part of the job is not welding but cutting: getting two dozen uprights and rails to identical length with an angle grinder is hard, and a few millimetres of variation is what produces a skewed frame. Tube cut to length removes that problem; assembly is well within reach at home.
If the shelving has to fit a specific room — height to the ceiling, depth to your boxes, engineered for a real load — we build custom metal shelving for warehouses, archives, workshops and retail.
