Most companies do not arrive at their first warehouse from nowhere. They arrive from a store unit, a back room, a corner of a workshop, or a unit they had outgrown two years before they admitted it. The stock was stacked on the floor, everybody knew roughly where things were, and it worked until it did not.

Then the new unit is signed and it looks enormous. That feeling is the single most reliable predictor of a layout that has to be redone within two years — because the natural response to a large empty space is to fill it, and filling a warehouse is not the same as laying one out.

Here is the order the decisions actually come in, and what to establish before anybody draws a single run.

The change nobody warns you about: you now store upwards

In a store unit you stack. Height is limited by what you can safely reach and what will not topple, so capacity is basically floor area.

In a warehouse, capacity is volume, and the racking exists to make the volume reachable. That inverts the arithmetic. Two units of the same footprint can hold very different amounts of stock depending on clear height, and a unit with more headroom is often better value than a bigger one with less — which is worth knowing while you are still choosing between units rather than after you have signed.

It also means the ceiling is not the limit. Clear height and how many levels you actually get goes through this properly: the number that matters is the height to the lowest obstruction over the storage area — a sprinkler head, a duct, a light fitting, a beam soffit — not the height to the roof, because the lowest thing over each area is what sets your top beam.

Five things to establish before anything is drawn

These are the inputs. Racking designed without them is guesswork wearing a drawing.

1. Floor loading. What the floor is rated for, from the lease or the landlord. Racking concentrates a great deal of weight onto small baseplates, so this is a real constraint rather than a formality — especially on an upper floor or a mezzanine.

2. Clear height to the lowest obstruction, per area. Not one number for the building. Measure it where the racking will go, because it usually differs across the unit.

3. The column grid. Measured centre to centre at floor level, and with base dimensions, because columns are frequently bigger at the bottom than the plan suggests. Whether your bay pitch divides the column grid decides more of your capacity than almost anything else — designing a layout around columns and obstructions covers why a column landing mid-bay costs you that bay in every run.

4. Doors and their clear zones. Where goods come in, where they go out, where the roller shutter swings and how far a lorry or a forklift needs in front of it.

5. What you actually store. Pallet dimensions, the weight of the heaviest pallet, how many SKUs, and how many of those move most weeks. That last figure decides the layout more than the total does.

The truck decides the aisle, and the aisle decides the capacity

This is the one that surprises first-time warehouse occupiers most, so it is worth stating plainly: your forklift determines how wide the aisles have to be, and aisle width is the largest single consumer of floor space in the building.

A counterbalance truck needs a generous aisle. A reach truck needs less. Narrow-aisle equipment needs less again, and imposes its own requirements on the floor. Choosing racking first and the truck afterwards is doing it backwards, and the consequence is either aisles you cannot use properly or a truck you now have to replace. Forklift turning radius and aisle width sets out the relationship.

If you already own a truck, say so at the start. The layout should be designed around the equipment you have unless you have decided to change it.

Density is not the goal. Access is.

Everyone new to this asks for the layout that holds the most pallets. It is the wrong question, and it is expensive to answer literally.

Selective racking — the ordinary kind, one pallet deep, aisle either side — gives you access to every pallet without moving another one. It holds fewer pallets per square metre than the dense systems and it is what most first warehouses should have, because it never blocks you.

Dense systems such as drive-in hold considerably more in the same footprint, but they buy that density by giving up access: you retrieve in an order dictated by how you loaded, which works for a few SKUs in large quantities and becomes a daily obstruction for many SKUs in small quantities.

So the question is not "how many pallets fit" but "how many pallets fit while my team can still reach what today's orders need". A warehouse that holds 20% more and costs an extra forklift move on every pick is not a better warehouse.

Not everything belongs on pallet racking either. Cartons picked by hand, small parts and slow-moving oddments usually want shelving instead, and mixing the two deliberately beats forcing everything onto beams — boltless shelving versus pallet racking goes through which stock wants which.

Leave room for the things that are not racking

The most common first-warehouse layout error is racking the whole floor.

A working warehouse needs space that holds no stock at all: somewhere inbound pallets land and are checked before they are put away, somewhere outbound orders are staged before collection, a bench where things get packed, somewhere damaged or returned goods sit while they are sorted out, and a place to charge the forklift with the ventilation and clearance that needs.

If none of that is designed in, it happens anyway — in the aisles, in front of the shutter, and in the space you were keeping clear. Then the aisle nearest the door silently becomes a staging area, and the racking there stops being reachable. Plan the empty space deliberately or it will be taken from you accidentally.

The same applies to the routes people walk. Escape routes and access to firefighting equipment are not something to fit around the racking afterwards — see escape routes and exit access in a racked warehouse.

Sprinklers, if the unit has them

If the warehouse is sprinklered, the sprinkler installation and the racking have to be considered together rather than in sequence, because what you store, how high you store it and how the racking is arranged all interact with the fire protection design. This is a genuine approval matter and not a detail to settle after installation — sprinkler clearance and racking approval covers what that involves.

If the unit is leased, three clauses change the design

Most first warehouses are leased, and the lease quietly constrains the racking.

Floor loading limits may be lower than you assume. Anchoring means drilling the landlord's floor, which usually needs permission and sometimes has conditions attached — and racking has to be anchored, so this is not optional. Reinstatement means that everything installed now may have to come out at the end, restored to the original condition, at your cost. That last one should influence what you buy, not just what you budget: standard, re-usable, relocatable components are worth more in a leased unit than a bespoke installation. Racking in a leased warehouse goes through all three.

Design for the warehouse you will have in three years

Not by buying racking you do not need — by leaving the layout able to grow.

Two cheap habits make the difference. First, keep the bay pitch and beam levels consistent, so that a later run matches what is already there and components interchange. A warehouse assembled from three incompatible systems is a maintenance and safety problem for its whole life. Second, leave a defined area for the next run rather than spreading everything out to fill the space. Expanding into reserved floor is straightforward; re-picking a whole warehouse to insert a run is not.

And keep the drawings. The layout, the load ratings and the component specification are what let anyone extend, repair or re-inspect it later — the handover documents your installer should give you lists what to insist on before the final payment.

Once it is up

Two things on day one. Load notices displayed on each run, stating the safe working load, so nobody has to guess — load notices and SWL signage covers what they should say. And anchoring checked and recorded, because it is the thing most likely to have been rushed at the end of an installation and the thing that matters most in an impact — anchoring pallet racking to the floor sets out what to look at.

After that it is routine: brief the forklift drivers, look at the uprights near the aisle ends regularly, and report impacts rather than hoping.

The short version

Get the floor loading, the clear height to the lowest obstruction, the column grid, the door zones and your real pallet data before anyone draws anything. Choose the truck before the aisle. Prefer access over density unless your stock profile genuinely justifies a dense system. Reserve floor for goods-in, goods-out, packing, quarantine and charging before racking the rest. Keep bay pitch and beam levels consistent so the second phase fits the first. And treat a leased unit's floor loading, anchoring permission and reinstatement terms as design inputs rather than paperwork.

What we do is set out on the racking page and the services page. We survey before quoting, because a layout drawn off a landlord's plan without measured columns and a real obstruction height is not a layout.

Moving into your first warehouse? WhatsApp us on 9107 2601 — tell us the floor area, the lowest obstruction height over the storage area, what you store and what truck you run, and we will tell you what the space will realistically hold before anything is drawn.