Steel deck

A galvanised steel platform unit that hooks onto ledgers or frame heads and forms the hard-wearing working surface of a system scaffold.

Also called: steel board, steel plank, steel platform unit, system deck

A steel deck is the robust platform unit of a system scaffold. Bricklayers, renderers and facade crews stand on it, stack blocks on it and push wheelbarrows across it. Each deck passes its load to the ledgers or frame heads at both ends. In most system scaffolds the decks do a second job that is easy to overlook: hooked in firmly, they brace the lift in the horizontal plane. That is why they cannot simply be swapped for loose timber boards.

Design and sizes

The deck is a pressed, hot-dip galvanised steel profile with a perforated or embossed walking surface. Water drains through the holes and boots find grip. Claws at both ends sit either on a U-profile or on a round tube, and this is the key distinction when you buy: a deck made for U-ledgers will not sit safely on a tube, and the reverse is just as true.

Width: usually about 0.32 m, in some systems 0.29 m; narrow decks of roughly 0.19 m fill the remaining space.
Layout: a 0.70–0.73 m wide scaffold takes two decks side by side, a 1.00–1.09 m bricklaying scaffold takes three.
Lengths match the bay sizes of the system, from 0.73 m up to 3.07 m and beyond in some ranges, with 2.57 m and 3.07 m the most common.

Capacity drops as the span grows. A common pattern under EN 12811-1 is load class 6 (6.0 kN/m²) up to about 2 m, class 5 at 2.5 m and class 4 (3.0 kN/m²) at 3 m. What counts is the data published for the specific system. Background on the figures: how load and width classes work.

Fitting and securing

Hold the deck with both hands, engage the claws on one side and lower the other end into place. Decks that are dropped end up with bent end fittings. Close each bay completely, cover gaps towards brackets and secure the decks against uplift: in intermediate lifts the next frame usually does this, on the top lift a guard rail post or a deck lock. Check that every claw sits fully before anyone walks on it.

Checking used steel decks

Claws and end caps: bent or cracked claws are the most frequent defect, and a deck that does not seat properly can slide off.
Straightness: a deck that sags without load or is twisted has been overloaded and goes on the scrap pile.
Welds where profile and end cap meet: look closely for hairline cracks.
Caked mortar: it adds kilos and hides damage, so clean before you judge.

Scratches and dull zinc are normal on used stock; dented end caps are not. Used decks of the common systems are listed under decks and boards.

Typical mistakes

Fitting decks from another system because the length looks right, leaving a bay half-decked for a moment, and throwing decks down during dismantling. Take decks out only after the lift above has been removed, and hand them down rather than letting them fall.

Frequently asked questions

How much load can a steel scaffold deck take?

That depends on its length. Short steel decks often reach load class 6, while a deck of around 3 m is typically rated load class 4, i.e. 3.0 kN/m². The binding figure is in the documentation for the system.

Does every steel deck fit every scaffold?

No. The end fittings are made either for U-ledgers or for tube supports, and the length must match the bay. Only decks approved for the scaffold system may be used.

How many steel decks go into one bay?

Two decks of about 0.32 m fill a 0.73 m wide scaffold; a bricklaying scaffold of roughly 1.00–1.09 m width needs three.