Most guides to warehouse racking list the types we happen to sell and stop there. This one covers the whole landscape, including the high-density systems KC Supply does not supply, because choosing racking badly is expensive and the mistake is nearly always the same one: picking a system for how many pallets it holds without checking how many of them you can actually reach.
That trade-off — selectivity against density — is the spine of this guide. Get it right and the rest of the specification follows.
The one trade-off that decides everything
Selectivity is the proportion of pallets you can pick without moving another pallet first. Density is how many pallets fit into the footprint. Every racking system on the market is a position on that line, and the two ends behave very differently:
- Single-deep selective pallet racking gives 100% selectivity — every pallet is directly reachable — and the lowest density, because every bay needs an aisle beside it.
- High-density systems store far more pallets per square metre and give up direct access, so you are working last-in-first-out, or shuffling pallets to reach the one you want.
The practical rule: density pays when you have few SKUs and many pallets of each. Selectivity pays when you have many SKUs and few pallets of each. A cold store holding twelve products by the hundred pallets and a spares operation holding four thousand part numbers by the pallet need opposite systems, and a system chosen for the wrong one of those will feel wrong on day one and never improve.
Systems we supply
Selective pallet racking
Adjustable beam-and-frame bays holding palletised goods several levels high — the default for good reason. Our STOW conventional pallet racking is modular, so bay widths, beam heights and capacities configure to your pallet sizes and forklift access. It is the cheapest route to high-density selective storage, and the easiest to reconfigure when the stock profile changes.
A note on price: modular racking is quoted per configuration, which is why you will see it listed without a headline figure. Any single price you see advertised for a racking system is the price of one layout of it, not of the system — ours included. Treat competitor headline figures the same way. The pallet racking buying guide covers bays, beams and load ratings in detail.
Cantilever racking — and the finding that surprises people
Cantilever racking has no front uprights, so timber, tube, bar, pipe, board and profile load along the full length of the rack. Arms come parallel (evenly distributed heavy loads) or tapered (lighter, longer items), single- or double-sided, and are height-adjustable in 150 mm increments with removable end stops.
Here is the part worth knowing before you order. The products with "cantilever" in the name are not the strongest ones in the category. From our own live product data:
| Rack | Rated capacity |
|---|---|
| GPC Cantilever Racking | 250 kg per arm |
| Cantilever Parallel Arms | 200 kg per arm |
| Cantilever Tapered Arms | 200 kg per arm |
| Heavy Duty Bar Storage Racks | 500 kg per arm |
| Heavy Duty Bar CUBI-Rack | 3,000 kg per column |
A bar rack carries twice as much per arm as a cantilever rack, and costs less than the parallel-arm unit. For steel bar, hollow section, angle and channel, the rack with "cantilever" on the label is the weaker and dearer choice. Cantilever earns its keep on length and open-face reach, not on weight. Two cautions travel with those figures: the ratings are per arm, not per bay, and every rack in the range instructs you to load heavy material at the base. See timber, pipe, steel and bar storage racks and the cantilever buying guide.
Longspan shelving and heavy-duty shelving
The hybrid: racking-scale bays, hand-loaded like shelving, no forklift. Right for bulky boxed goods, spares and picking faces where a forklift would be overkill. See heavy-duty shelving, the longspan guide, and industrial shelving vs pallet racking for the dividing line.
Vertical and long-load racks
Vertical sheet racks and long-load storage keep board, panel, tube and section upright, visible and quick to retrieve, and free up bench space. Ours have 250 mm between support bars (and 250 mm between arms on the bar racks), are fully welded, and are pre-drilled for bolting to the floor.
Mezzanine platforms
When the floor is full but the height is not, a mezzanine creates a raised floor for storage, picking or light assembly — often the cheapest way to expand without moving premises. See adding a storage level.
Systems we do not supply — and what they are for
If one of these is what your stock profile actually calls for, we would rather tell you here than sell you the wrong thing. All are specialist installed systems; go to a racking systems integrator.
- Drive-in and drive-through racking. The forklift drives into the lane and sets pallets on rails. Highest density of any static system, lowest selectivity. Drive-in is one entrance, so last-in-first-out; drive-through is open both ends, giving first-in-first-out. Suits very few SKUs, very many pallets — cold stores, beverages, seasonal bulk. Expect lane damage: the truck is inside the structure.
- Double-deep racking. Two pallets deep, roughly halving the aisles. Around 50% selectivity and it needs a reach truck with a pantograph or telescopic fork — a normal counterbalance truck cannot reach the back pallet. Cheap density if you already run the right truck.
- Push-back racking. Pallets sit on nested trolleys on an incline; loading pushes the row back, removing one lets the next roll forward. Last-in-first-out, but far more selective than drive-in because every lane is a face.
- Pallet flow (gravity) racking. Rollers on a slope; load one end, pick the other. Genuine first-in-first-out and very high throughput. The most expensive per position and unforgiving about pallet quality — a broken or bowed pallet is what jams the lane.
- Narrow aisle and very narrow aisle (VNA). Not a rack type but a layout: standard selective racking set at aisles a special truck can work in, keeping 100% selectivity while recovering much of the floor an aisle would have taken. Needs a VNA truck, wire or rail guidance, and a floor flatness specification — the floor, not the rack, is usually what makes VNA impossible in an existing building.
- Mobile (shuttle) racking. Bays on powered rails that close together, opening one aisle at a time. Very high density with full selectivity, at high capital cost. Common in cold storage and archives.
Aisle width: the number that decides your layout
Racking is sized by the truck, not the other way round. The figure to design to is your truck's right-angle stacking aisle — the width it needs to turn and place a pallet square into a bay — plus a working clearance.
Indicatively, a counterbalance forklift wants somewhere around 3.5–4.2 m, a reach truck around 2.7–3.2 m, and a VNA truck around 1.6–1.9 m. Treat those as orientation only. They vary widely with mast, load centre, pallet size and tyre type, and the only number worth designing to is the one on your own truck's data sheet, for your own pallet. A layout drawn from a generic table is the most common way a racking project goes wrong before anything is ordered.
Two more constraints belong on the same drawing: the pallet (UK 1200 × 1000 mm and Euro 1200 × 800 mm behave differently in the same bay — see UK pallet sizes explained), and the building — clear height under the lowest obstruction, sprinkler positions, column grid and door heights.
Two delivery-day facts that are not on most spec sheets
- "A fork lift will be needed to unload these units" appears on almost every rack in our range. No forklift on site on delivery day means the rack does not come off the lorry.
- Floor fixings are not supplied — on racks that are pre-drilled precisely because they need bolting down. The right anchor for a screeded slab is not the right anchor for a thin or suspended floor, so the fixings get specified against the actual floor.
Five questions that settle the choice
- How many SKUs, and how many pallets of each? Many SKUs, few pallets → selective. Few SKUs, many pallets → high density.
- Does stock rotation have to be FIFO? If yes, drive-in and push-back are out; drive-through or pallet flow are in.
- What truck do you already own? The truck constrains the aisle and the aisle constrains the system. Changing the truck is usually the bigger cost.
- Is the load palletised at all? If not, you want cantilever, long-load or vertical racks, not pallet racking. Hand-picked boxes want shelving.
- What is the clear height, and what is the floor? Height decides whether a mezzanine or taller bays are the cheaper capacity; floor flatness and slab thickness decide whether the dense options are available at all.
Once it is installed
Racking must be specified to its rated load, loaded within it, and inspected. Load notices, upright protection and barriers in forklift aisles, and periodic inspection in line with SEMA guidance and PUWER are covered properly in our guides to racking inspection, SEMA and HSG76 and upright guards and barriers. If you are working out heights and patterns, see pallet stacking and storage, and for what UDL and SWL actually mean, load ratings explained.
Browse the full racking & shelving range, and the handling equipment that feeds it — pallet trucks, stackers and platform trucks and trolleys. Tell us the SKU count, the pallet, the truck and the clear height, and we will tell you which system fits — or that the one you need is not one we sell.