TYPES OF WAREHOUSE RACKING

Selectivity Versus Density, Explained With Numbers

Every racking type is a trade between how many pallets you fit and how easily you reach any given one. Selective APR at 2,700 mm aisles typically yields around 45–50% floor utilisation, and every pallet is reachable without moving another. Narrow aisle keeps 100% selectivity and lifts utilisation to roughly 60–65% by cutting the aisle to 1,600–1,900 mm. Push-back reaches around 75% with one SKU per lane, and drive-in tops out near 85% at the cost of truck excursions into the structure.

The figure nobody quotes is honeycombing — the empty positions in a partly-picked deep lane. A six-deep drive-in lane holding an SKU with an average of three pallets on hand is running at half capacity in practice, which is how a system chosen for density can end up storing less than the selective racking it replaced. We model your actual SKU depth before recommending anything dense.

Pallet live storage sits apart because it is FIFO by design: loaded at the back, picked at the front on gravity rollers. It suits date-coded food and pharma where rotation is a legal or contractual matter rather than a preference.

• APR — 100% selectivity, 45–50% utilisation, lowest cost per bay
• Narrow aisle — 100% selectivity, 1,600–1,900 mm aisles, guided trucks
• Drive-in — up to 85% utilisation, LIFO, best for cold stores
• Drive-through — FIFO version, open at both ends
• Push-back — around 75% utilisation, no truck entry, 2–6 deep
• Pallet live — FIFO gravity flow for date-coded stock
• Cantilever — long loads, arms rated 500–1,500 kg each
• Mezzanine — adds a floor rather than a rack, 350–500 kg/m²

Components Common to Every Type

Whatever the system, the same parts do the work. Uprights are cold-rolled sections perforated at 50 mm or 75 mm pitch; frame depth is normally 900 mm for a 1200 x 800 mm Euro pallet and 1,100 mm for a 1200 x 1000 mm pallet, giving a nominal overhang front and rear. Beams are box sections with welded connectors, rated as a pair — commonly 1,500 kg to 4,000 kg UDL depending on section and clear span.

Beam pitch is set by pallet height plus a clearance of around 100–150 mm for lift-off. Bracing patterns, base plates and floor fixings are part of the structural design and must not be altered on site. Connector geometry differs between manufacturers, so beams and frames from different brands must never be mixed — an apparently seated beam may be engaging on a fraction of its designed lug area.

How to Choose — The Questions We Ask on Survey

How many pallets do you hold per SKU on an average day, and at peak? What is the clear height to the lowest obstruction, and where are the sprinkler deflectors? What trucks do you own, what do they lift to, and what aisle do they need? Is stock date-coded? Do you handle long loads? What is your heaviest single pallet, not your average?

Those seven answers determine the system. Everything else — brand, new or used, finish, lead time — follows. If a supplier quotes a racking type before asking them, they are selling what they have in stock rather than what your building needs.