Beams carry the load. Decking is what stops the load falling between them. That distinction sounds obvious written down, and it is behind most of the decking problems we are called out to look at — because a great many people specify decking as though it were a shelf, when structurally it is a bridging component with its own rating and its own failure mode.

Racking without decking works perfectly well for one thing: full pallets, seated on the beams, in a system designed for exactly that. The moment anything else goes on the rack — cartons, small items, oddly-sized loads, a damaged pallet — you need a deck, and the choice of deck starts mattering.

Steel panel decking

Steel panels are the closest thing to a general-purpose answer, and they are what you can see on every level in the installation above. Formed sheet steel spans between the beams, usually with return edges and sometimes with stiffening ribs, and the panels sit into the beam profile.

What they are good at: a solid, continuous surface. Small cartons cannot slip through. Loose items sit flat. The surface is easy to keep clean, which matters in food, pharmaceutical and any environment with a wipe-down regime. Panels are also comfortable for pickers working by hand, because there is nothing to catch a knuckle or a carton corner on.

What they cost you: panels block vertical movement. That has two consequences. Water from a ceiling sprinkler cannot pass down through the rack, and neither can light. In a building where the fire strategy depends on ceiling sprinklers reaching goods low in the rack, solid decking is exactly the thing the strategy did not assume.

Wire mesh decking

Wire mesh is a welded grid in a frame, with support channels underneath that sit on the beams. It is the standard where sprinkler performance is part of the conversation, because water passes straight through it, and light does too, so the lower levels of a run stay usable without extra lighting.

Mesh has a second advantage that gets overlooked: you can see through it. A dropped item, a leaking carton, a pallet sitting wrong — all visible from below or above rather than discovered later. For inspection that is worth something real.

The limits are the obvious ones. Anything smaller than the aperture goes through it, so mesh is wrong for loose small parts unless you add a liner. It is less comfortable for hand-picking, and in a wash-down environment it holds debris in places a cloth does not easily reach.

Chipboard and timber

Timber-based decking — chipboard, plywood, or boards laid across the beams — is cheap, quick, and very common in Singapore, particularly on boltless shelving and on racks that were adapted after installation rather than designed with decking from the start.

It has real uses. It gives a solid surface at low cost, it can be cut on site, and for light shelving duty it is perfectly adequate.

The problems are worth stating plainly. Timber is combustible, which puts it directly into the fire conversation in a way steel and mesh do not. It absorbs moisture, so in a humid warehouse or anywhere near a wash-down it swells, sags and eventually delaminates. And because it is easy to cut on site, it is the decking most likely to be a loose board resting on beams with nothing locating it — which is a different thing from a rated deck, however similar it looks.

The point everyone misses: decking has its own rating

This is the single most important thing on this page. The capacity of a deck is not the capacity of the beam pair it sits on. They are separate numbers arrived at separately.

A beam level might be rated for a substantial uniformly distributed load, calculated for that beam length and section. The decking spanning between those beams has its own rated capacity, based on its own span, its own gauge and its own support arrangement — and it is usually the lower of the two. Loading a deck to the beam's figure because the beam's figure is the one written on the load notice is a straightforward way to fail a deck that was never at fault.

Two related traps. A deck rated for a uniformly distributed load is not rated for the same weight applied through four small feet, because a point load concentrates everything into a fraction of the span. And decking is not a walkway. People do climb onto racking, and a deck that holds a pallet without complaint is not thereby rated to take a person's weight applied dynamically at one point. If access at height is genuinely needed, that is a designed platform question, not a decking question.

What actually goes wrong on site

Four things, in rough order of how often we see them:

Decking that is not located. Panels or boards resting on beams with nothing holding them in position. A forklift tine catching an edge lifts the deck, and once one is displaced the gap it leaves is the hazard. Located, engaged decking is not an upgrade; it is the difference between a component and a loose object.

Mixed depths. Decking cut for one beam depth reused on a run with different beams, so it is bearing on a fraction of the intended surface. It looks fine from the aisle.

Decking added later without checking the fire strategy. A rack originally installed open, decked in solid panels afterwards for picking convenience, in a building whose sprinkler design assumed water could get down through the racking. Nothing about the rack looks wrong afterwards, which is precisely the problem. Where sprinklers and racking interact, the clearances and the arrangement are part of the approval — we have set that out in our note on sprinkler clearance and racking approval.

Damaged decking left in place. A bent panel or a sagging board is a hazard that reads as cosmetic, and it is the item most likely to be skipped on a walk-round. It belongs on the same checklist as beams and uprights.

Choosing, in practice

• Full pallets only, in a system designed for them? You may not need decking at all.
• Ceiling sprinklers relied on to reach goods in the rack? Start from mesh and justify anything solid.
• Hand-picking small cartons and loose items? Steel panel, or mesh with a liner.
• Food, pharmaceutical or wash-down? Steel panel for cleanability, and check how the deck drains.
• Light shelving duty, dry environment, budget-led? Timber is defensible — provided it is located, and provided combustibility has been considered rather than assumed away.

What we ask before specifying

What is going on the level, and is it palletised, cartoned or loose. The heaviest single item and whether it lands as a point load. Whether people pick from it by hand. What the building's fire strategy assumes about water getting into the rack. Whether there is a wash-down regime. And the beam depth and span it has to sit on, because that is what the deck is actually rated against.

We publish indicative per-bay ranges for our selective systems on the racking page, but we do not publish decking prices: the deck depends on the span, the gauge, the environment and the fire strategy, and a per-square-foot figure quoted without those is a number that changes once someone looks. We quote it after a survey, with the rest of the system.

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More: pallet racking systems · mezzanine floors

Related reading: beam deflection and catalogue ratings · safety pins and locking clips · the racking inspection checklist