Cube utilisation
Cube utilisation — Storage volume occupied divided by storage volume available under the roof. Most warehouses that complain of being full are running on the bottom two thirds of their cube while the top third sits empty — the space was bought with the building and is already paid for.
Clear height versus usable height
Clear height versus usable height — Clear height is floor to lowest overhead obstacle. Usable height is clear height minus the sprinkler and lighting allowances your local fire and building codes impose, minus the safe working distance your racking spec demands. The gap between the two numbers is where permit problems live.
| Taller frames, same footprint | cheapest per pallet; needs slab check, aisle equipment reach, sprinkler review |
|---|---|
| Mezzanine floor | adds floor area, not just height; structure, stairs, fire route — a building permit conversation |
| Denser storage (drive-in, pallet shuttle) | height plus depth, but trades away selectivity; needs SKU fit analysis first |
| All three | only ever in that order of cost; height first, area last |
The empty third of your cube is inventory you already own
Warehouses are bought in cubic metres and managed in floor squares, which is why full-looking buildings usually top out two metres off the ground. Before any new storage is bought, the measurement that pays is the profile of loaded height along each aisle: where the rack stops, why it stops there — beam spacing, equipment reach, sprinkler line — and what the slab under that run was specified to carry. That profile is a map of already-purchased capacity with reasons attached.
Buy height first, area last
Taller frames on the same footprint are the cheapest pallet you will ever store, because the land, slab and roof are sunk. Mezzanines buy real floor area but at building-permit prices — stairs, fire routes, occupancy classification. Dense systems buy both height and depth by giving up single-pallet access, so they only win after a SKU-fit analysis says your stock rotates deep. The order is a cost law, not a preference: height first, density second, new floor last.
Can I just buy taller racks than the last instalment?
Not by yourself, because a taller rack rewrites three documents you do not own: the floor slab's load case, the sprinkler system's coverage assumption, and in many jurisdictions the permit under which the building is occupied. The honest sequence is a slab check, a fire-protection review, then the racking quotation — in that order, because each step can shrink the answer the next step gives.
How high is too high for hand-loaded shelves?
Above roughly shoulder height of the shortest person doing the picking, manual shelf loading stops being an ergonomics question and becomes an inventory-accuracy and injury question: the top shelf stops being used, stock skews to the bottom, and the height you paid for is dead. Put hand-picked SKUs between knee and shoulder, put replenishment bulk above, and let only machines load the sky.