Widening the scaffold: planning inside and outside brackets, width classes and wall gap
The width of a facade scaffold is fixed when you buy it. A frame that is 0.73 m wide today will be 0.73 m wide on every job. Yet almost every site has a spot where that width is wrong: insulation still to come leaves a gap at the wall, the roofer needs a wider catch lift at the eaves, or pallets have to be stored on one lift. Brackets solve this, locally and within limits.
Four reasons to widen
- Wall gap too large: the scaffold stands further from the facade than wanted, because of a plinth, insulation yet to be fitted or a balcony. The answer is an inside bracket.
- Working area too small: for bricklaying or stonework with material on the deck, 0.73 m is tight. An outside bracket or a wider system adds space.
- Roof edge protection: at the eaves the top lift must reach out beyond the gutter so the protection screen has the required distance. Depending on the overhang, that needs inside or outside brackets; see roofing scaffolding.
- Protection over a footway or entrance: a fan is carried on wide brackets so falling objects miss passers-by.
Width classes under EN 12811-1
EN 12811-1 sorts working scaffolds into width classes according to the usable deck width between the edge protection planes, not the frame centres.
| Width class | Clear width | Typical use |
|---|---|---|
| W06 | at least 0.6 m, less than 0.9 m | Painters, renderers, roofers; systems around 0.73 m wide |
| W09 | at least 0.9 m, less than 1.2 m | Bricklayers, stonework; systems around 1.09 m wide |
| W12 | at least 1.2 m, less than 1.5 m | Heavy facade work, machinery on the deck |
| W15 and above | 1.5 m upwards, in 0.3 m steps | Industrial and special uses |
A 0.73 m frame scaffold with two boards of about 32 cm is W06. Add an outside bracket with two more boards and that lift roughly doubles in width, but the bracket deck does not automatically have the same load class as the main bay. Background in load classes and width classes explained.
The wall gap and the 30 cm rule
There is always a gap between the inner edge of the deck and the facade. Up to about 30 cm is generally accepted in European practice without inside edge protection; national rules or site requirements may be stricter. Above that, someone can fall between scaffold and wall, and there are two options: reduce the gap with an inside bracket and an extra board, or put edge protection on the wall side too, with two rails and a toe board as on the outside.
The inside guard rail is quick but blocks exactly the side being worked on, so painters and renderers prefer brackets. On roof work at the catch lift, or where the wall is not touched, the guard rail is often more practical. Remember that the gap changes: on an insulation job it is wide at the start and narrow at the end, and the scaffold has to suit both stages. More in scaffolding for external wall insulation.
Inside and outside brackets
Inside bracket
An inside bracket attaches to the standard nearest the wall; on frame systems mostly to the frame node or with a half coupler, on modular systems with a wedge head at the rosette. Its reach is typically 0.30–0.39 m, enough for one narrow board. Because it is short, many systems allow it on every lift without extra support. It still adds load to the inner standard, and in some systems the bracket deck has a lower load class than the main bay. Check whether standards with inside brackets need extra ties, and note that the tie tube has to pass the bracket: larger wall gaps need longer ties, and the tie must not rest on the bracket.
Outside bracket
An outside bracket projects beyond the outer standard. On a 0.73 m system it usually takes two boards; fan brackets reach around 1.0–1.1 m. It acts as a lever, so most versions need a bracket brace to the lift below, the guard rail moves to its outer edge on a spigot-mounted post, its boards must be locked against uplift and butt tightly against the main deck, and the standards concerned often need closer ties. Our guide to cantilever brackets goes into detail, including checks on used ones.
On frame scaffolds, brackets sit only at deck level, which makes them quick and flush with the main deck but rules out intermediate platforms. Modular systems with nodes about every 0.5 m allow a bracket between main lifts, for example a stepped catch lift under a deep overhang or a platform at cornice height. Make sure bracket and board suit the same bearing type, U-section or tube.
Worked example: insulating a 20 m elevation
A block of flats has a 20.6 m long eaves elevation, 10 m to the eaves, and receives 16 cm insulation boards with about 1 cm render: the finished wall grows outwards by 17 cm. The roof overhang is 45 cm.
- Final state: after rendering, the gap between deck and finished face should be no more than 30 cm, ideally about 20 cm.
- Scaffold position: 17 cm build-up plus 20 cm working gap gives about 37 cm from the bare wall to the inner edge of the deck.
- Initial state: while boards are being fixed, the gap to the bare wall is 37 cm, more than 30 cm. Fit inside brackets with one board for that phase, removed afterwards, or an inside guard rail.
- Roof edge: 45 cm overhang plus the new wall thickness may require extending the top lift with an outside bracket.
- Ties: tie standards with brackets and roof protection as specified, and order ties long enough for insulation plus bracket.
- Quantities: eight bays of 2.57 m give nine frame lines; five working lifts at about 2, 4, 6, 8 and 10 m give 9 × 5 = 45 inside brackets for this elevation, plus bracket boards, locks and, for the top lift, outside brackets with braces and posts.
The scaffolding calculator gives the base scaffold; add the brackets from your own list. Brackets in various reaches are in our bracket section.
Brackets or a wider base system?
Brackets are a tool for particular places and phases. Fitted on every lift and every frame line, they amount to a wide scaffold built from many separate parts, with more work and more sources of error. Insulation phases, roof edges and single storage points call for brackets. Bricklaying over all lifts calls for a 1.09 m system. On a tight boundary, inside brackets on a narrow system are usually the better choice.
Typical errors
- Outside bracket without brace: it holds when empty and deforms under load.
- Unlocked board on an inside bracket, lifted by a gust from below.
- Guard rail left on the main bay while the bracket deck lies unprotected in front of it.
- Pallets of blocks on a bracket deck approved only for light work.
- Brackets from another system made to fit: there are no valid load values.