Scaffold decks compared: steel, aluminium, combi, timber and ladder deck
When people put a scaffold together, they think about frames and height first. The decks, however, shape the daily work more than anything else. They decide how much material a lift may carry, how heavy each piece is to pass up, and how long the scaffold lasts. A scaffold for a detached house easily contains 100 to 150 decks, so the choice is also a question of tonnes and budget.
Three jobs a deck does at once
In a system scaffold a deck is more than something to stand on:
- It carries the load of people, tools and materials and passes it to its supports: on frame scaffolds usually a U-section at the head of the frame, on modular systems a U-ledger or a tubular ledger.
- It stiffens the lift horizontally in many systems, because the hooked-in decks stop the bay from racking. Take a system deck out and replace it with a loose plank, and that bracing has to come from elsewhere, for example horizontal diagonals.
- It closes the surface together with the toe board, so that nothing falls through.
The type of support matters too. A deck made for a U-section does not sit properly on a round tube ledger, and the reverse is also true. Only decks listed in the system's documentation belong in the scaffold.
The five common deck types
Steel deck
A pressed steel profile, hot-dip galvanised, with a perforated or embossed walking surface for grip and drainage. The usual width is around 32 cm: two fill a 0.73 m wide scaffold, three fill a 1.09 m bricklaying scaffold. In many systems steel decks reach high load classes in short and medium bays, often class 6 up to about 2 m bay length and lower classes above that. A deck of about 3 m weighs roughly 20–25 kg. Service life is very long as long as the zinc stays intact and the hooks are not bent. Downsides: weight when passing up and transporting, and a cold, sometimes slippery surface in wet or frost. See the glossary entry on the steel deck.
Aluminium deck
An extruded hollow-box profile of similar width, also available in wider sections. Short aluminium decks also reach high classes, but capacity usually drops faster than steel as the bay gets longer. It is about a third to a half lighter than a comparable steel deck. It dents more easily, and fresh cement or lime mortar attacks the surface. Typical users: painters, roofers, interior fitters and anyone who rebuilds the scaffold often. More in the entry on the aluminium and combi deck.
Combi deck and heavy-duty panel deck
A frame of aluminium or steel holding a coated plywood board or an aluminium sheet. Being roughly 0.6 m across, a single panel decks out a 0.73 m scaffold practically on its own. Heavy-duty versions have a thicker board and a stronger, often steel frame. Light panels in long bays often do not exceed class 3, robust ones go higher. The surface is closed and pleasant to walk on. The plywood is the wearing part: swollen edges, delamination and soft spots are reasons to reject. Some designs allow the board to be replaced.
Ladder access deck
Essentially a panel deck with a hinged hatch and often a built-in ladder. It takes the place of one standard deck in the bay where people climb up. Because the opening weakens the deck, hatch decks usually carry less than full decks, commonly class 3. No materials on the hatch. See the ladder access deck entry and our guide on scaffold access.
Timber scaffold board
Softwood boards were the standard deck for generations, and they still are on tube and fitting scaffolds, in the UK designed to NASC TG20, as well as in make-up bays, special structures and as covers. Boards must be graded and marked for scaffold use; how far a board may span is a function of its section and the load class, as tabulated in the relevant standard or design guide. They can be cut for special cases and are cheap to buy, but they give no bracing effect, must be secured against sliding and uplift, absorb water and suffer from rot, splits and damaged ends. Their life is much shorter than that of metal decks. More in the entry on the timber scaffold board.
Comparison table
Weights and classes are rough guide values for decks around 3 m long. The binding figures are in your system's documentation.
| Deck | Width | Weight | Capacity in long bays | Service life | Typical use |
|---|---|---|---|---|---|
| Steel | approx. 32 cm | high | high | very long | bricklaying, render, heavy facade work |
| Aluminium | approx. 32 cm | low | medium to high | long, sensitive to dents | painting, roofing, frequent changes |
| Light combi panel | approx. 60 cm | medium per panel | rather low | board wears | painting, interiors, light work |
| Heavy-duty panel | approx. 60 cm | medium to high | medium to high | long, board may be replaceable | general facade work, heavy foot traffic |
| Timber board | varies | medium | depends on section and span | shorter | tube and fitting, special bays |
| Ladder access deck | approx. 60 cm | medium | usually class 3 | hatch and hinges wear | access bay |
Bay length and load class: the key relationship
The longer a deck, the less it carries. That applies to every material. EN 12811-1 defines the uniformly distributed loads per class, and the numbers become tangible once you multiply them by the bay area (1 kN corresponds to about 102 kg):
- Painter's bay, 2.57 × 0.73 m = 1.88 m². Class 2 (1.50 kN/m²) allows about 2.8 kN, roughly 285 kg: two painters, buckets and a pressure washer.
- Bricklayer's bay, 2.07 × 1.09 m = 2.26 m². Class 4 (3.00 kN/m²) allows about 6.8 kN, roughly 690 kg. Class 6 (6.00 kN/m²) allows about 13.5 kN, roughly 1,380 kg.
A pallet of concrete blocks can weigh more than a whole class 4 bay may carry, which is why bricks are spread in part loads and masonry work uses shorter bays with strong decks. Two further points: there are also requirements for concentrated and partial-area loads, and the weakest deck in a bay governs. If a light bracket deck or a hatch deck sits next to two steel decks, that part sets the limit there. The classes themselves are set out in full under load classes and width classes.
Which deck for which trade, and what it costs over time
- Bricklayers and concrete work: steel or heavy-duty decks in bays up to about 2.5 m, scaffold width around 1.09 m.
- Renderers: steel when bags and tubs stand on the lift; with machine-applied render via hose, lighter decks are often enough.
- Painters: aluminium or combi panels, since little material is stored and the scaffold changes often.
- Roofers: light decks on the working lifts, robust decks at the catch platform, as permitted in the instructions.
- Interiors and birdcage scaffolds: panels or aluminium decks for a closed, light working surface.
Many contractors run a mixed fleet: steel for heavy lifts, aluminium or panels for the rest, all from the same system. For the economics, think about how often the scaffold goes up and down each year, how many decks pass through your hands each time, and how much material stands on a lift on average. If you rebuild rarely and work heavy, steel wins. If you rebuild often and work light, aluminium or panels save labour. Panels with plywood need dry storage, or the board becomes an early wearing part.
Typical mistakes
- A deck for U-sections laid on a tube ledger: it does not seat and can slip off.
- Decks from another system that fit “somehow”, with no proven capacity.
- Missing deck locks, so a gust from below can lift single decks.
- Decks that visibly sag or no longer lie flat, still in service.
- Mortar tubs and bricks on the hatch deck.
- Unmarked boards from a builders' merchant used as scaffold boards.
Choose decks for the heaviest work the scaffold will see and for the weight your team can handle every day. Single decks in the right length and version, used or new, are in our decks and boards section; how to judge used ones is covered in checking used scaffold decks.