Scaffolding for roof work: catch deck, screen and hoisting
Nobody stands upright on a pitched roof. Anyone who slips slides to the eaves and over the edge unless something stops them. That is why a scaffold for roof work is not mainly a facade platform: its first job is to catch people at the edge. Its second job is logistics, because old tiles, battens and insulation must come down and new covering and insulation must go up. This guide explains how one scaffold does both, and what to agree with the roofer before erection.
A scaffold that catches, not just carries
A facade scaffold protects the people standing on its deck. During roof work most people stand above the scaffold, on the roof. For them the scaffold must act as a catch platform: someone who slips should land on the top deck and be held by a protective screen instead of going over the edge. This arrangement is called a roof catch scaffold or eaves protection.
When such protection is mandatory depends on roof pitch, fall height and national rules. In the UK the Work at Height Regulations 2005 put preventing falls first, which on a pitched roof normally means edge protection at the eaves; in other countries the national regulations apply, and a safety adviser can say what is required. Anchor points with personal fall protection are an alternative only where a scaffold is technically impossible, and they require training and a rescue plan.
The catch deck at the eaves
Three dimensions decide how well a catch scaffold works:
- Deck height: a widely used limit is a maximum of 1.5 m (about 5 ft) between the eaves edge and the top deck. With 6 m to the eaves, the deck sits at 4.5 m or higher. If it is lower, a sliding person falls too far.
- Deck width: the deck must be wide enough to catch a person. A 0.73 m frame scaffold is often widened with a bracket on the outside or inside, depending on overhang and the manufacturer's instructions.
- Protective screen: above the deck stands a screen of netting or mesh that rises well above the roof surface at the eaves. Height and distance depend on pitch, regulations and the system manual; the steeper the roof, the taller the screen. See roof edge protection screen.
Work the lift heights out on paper. Example: eaves at 6 m, base jacks extended 0.3 m, frames 2 m high. The decks land at about 2.3 m and 4.3 m, leaving 1.7 m to the eaves, which is too much. Insert a compensation frame 1 m high at the base, and the decks rise to 3.3 m and 5.3 m, only 0.7 m below the eaves.
Overhangs, verges, dormers and flat roofs
Many houses have eaves overhangs of 400–800 mm. The scaffold cannot stand close to the wall at full height, because the top lift would hit the rafter feet and soffit. For catching that would be wrong anyway: the deck belongs below and in front of the eaves edge. The scaffold is therefore set out far enough from the wall that the screen stands outside the eaves, and the gap to the facade in the lower lifts is closed with inside brackets so those lifts stay safe to work on.
The eaves are not the only edge. At the verge above the gable, someone can fall sideways. A gable scaffold whose edge protection rises above the verge deals with this; it follows the slope in stepped lifts, with an end guard rail and toe board at every step. Dormers, roof windows and openings created during the work are further edges, and a stripped roof without battens is a fall hazard into the building. The roofer protects these with covers or guard rails; the scaffold alone is not enough. On a flat or low-pitch roof there is no sliding motion, so a guard rail at the roof edge usually suffices, either by taking the scaffold high enough that its rails project above the edge by the required amount or by fixing edge protection to the parapet.
How much material moves
The quantity is almost always underestimated. Take a block of flats with a 12 × 18 m footprint and a 35° pitched roof:
- Rafter length per slope: half the width, 6 m, divided by cos 35° (0.82) gives about 7.3 m.
- Two slopes of 18 m length make about 264 m²; with overhangs roughly 290 m².
- Clay or concrete tiles weigh roughly 40–50 kg per m² of roof.
- For 290 m² that is about 11.5 to 14.5 tonnes of new covering going up and about as much old material coming down.
Battens, membrane and insulation come on top. The scaffold therefore needs a landing point for a hoist and a way to get waste down.
Hoist, landing point and rubbish chute
Roofers mostly use an inclined hoist running on a ladder track from the ground to above the eaves; tiles are delivered straight onto the roof or onto the scaffold. Three points matter:
- Opening in the edge protection: open it only as wide and for as long as necessary. Hinged or hook-in gate rails are common.
- Load at the landing: tile packs put down on the deck create point loads. The landing bay must safely reach its load class, and packs are spread out at once or taken straight onto the roof.
- Clear track: the hoist must not collide with scaffold parts, ties or nets.
Old tiles and battens travel down a rubbish chute, mounted on the scaffold and loaded from the roof or the deck, into a skip. With fibre-cement sheets on older buildings, find out first whether asbestos is present. If so, separate rules for removal and disposal apply and a licensed specialist is needed.
Protection below, weather above
Something always falls from a roof under repair: a tile fragment, a batten, a nail. Over entrances, terraces and footpaths, fit a protective fan or close the area off; nets on the outside hold back smaller items. An open roof also lets the rain in. On small jobs roofers work in sections and close each one with membrane in the evening. On larger projects or in uncertain seasons, a temporary roof over the whole building can make sense. Its loads are carried by the scaffold and raise wind and snow loads considerably, so it needs its own structural design by specialists.
| Phase | Role of the scaffold | Watch out for |
|---|---|---|
| Erection | catch deck, gable scaffold, screen | deck height to eaves, inspection before handover |
| Stripping | chute, catch protection | do not collect old material on the deck |
| Roof structure, insulation | workplace at eaves and verge | protect open roof areas separately |
| New covering | hoist, landing, catch | spread tile packs immediately |
| Gutters, flashings | workplace below the eaves | screen stays until the end |
| Dismantling | top down | roof completely closed first |
After the covering come gutters, downpipes and flashings, and the screen is often felt to be in the way. It stays until nobody works on the roof any more (see gutter scaffolding).
Responsibilities, mistakes and preparation
Whoever erects the scaffold inspects it after erection, records the inspection and marks at the access what use and load class it is released for. Every firm using the scaffold checks it visually before starting; a missing net panel, a shifted bracket or a loose tie is reported and put right first. A homeowner who provides their own scaffold needs a competent person to erect and inspect it to the instructions, and a roofer will rightly refuse to step onto a scaffold without a traceable inspection.
Common mistakes: lift pattern not calculated, so the top deck is too low; screen too short for the pitch; unprotected verges; hoist gate left open; tile packs on one bay; screen removed before the gutters were done; no fan over an entrance still in use.
If solar panels follow the new covering, check early whether the installer can use the catch scaffold and needs a hoist (see solar panel scaffolding). Ask the roofer for three figures: pitch, exact eaves height on every side and hoist position. Then plan the lift pattern, stepped gable scaffolds, a fan over the entrance and a place for skip and chute. The scaffolding calculator works out frames, brackets and screen. Only when the scaffold has been inspected and handed over is the first area of roof opened.