Access to the scaffold: ladder bay, external ladder tower or stair tower?
A scaffold is only as good as the route up to the working lift. Anyone who climbs ladders ten times a day with a paint bucket knows what access means by the evening. And anyone who has seen a colleague climb up the outside of the frames because the ladder was at the far end knows that badly placed access soon becomes a safety problem. Access deserves the same planning as lift heights and ties.
What the rules expect
Every working scaffold needs safe access to every working lift. Climbing frames, standards or braces is not allowed anywhere. In the USA, Subpart L of OSHA's construction standard 29 CFR 1926 requires proper access such as ladders, stair towers or ramps and rule out cross braces as a means of access. British practice, based on the Work at Height Regulations 2005 and NASC guidance, treats access as part of the scaffold design. Many European rule sets go further and give stairs priority, with ladders accepted where a stair is disproportionate because the scaffold is low, used only briefly or lacks space. Whatever applies in your country, the site risk assessment decides what is adequate.
The distance to the nearest access also matters, so that everyone can get down quickly in an emergency. On long scaffolds, a walking distance of no more than about 50 m to the next access point is often used as a planning figure.
The ladder bay with hatch decks
In a ladder bay, one ordinary deck per lift is replaced by an access deck with hatch, usually with a ladder fixed underneath. You climb from lift to lift inside the width of the scaffold. With the hatch closed, it is a normal part of the working platform.
- Stagger the hatches. Openings alternate from one end of the bay to the other on successive lifts, so nobody can fall through several lifts.
- Close the hatch after every passage; a hatch left open is simply a hole in the platform.
- A safe start at the bottom: the lowest ladder stands on a deck in the base lift or on firm ground and is secured against slipping. On soft ground it sinks and twists.
- Respect the load class. Hatch decks often carry less than full decks, typically class 3. Store material in the neighbouring bays.
- Ladder to suit the lift height, usually about 2 m. A separate scaffold ladder is hooked in and secured as the instructions show.
A ladder bay costs no extra bay and hardly any extra material. Its weakness shows in daily use: both hands belong on the ladder, so tools and material have to go up another way. For heavy or bulky items it is unsuitable.
The stair tower
A stair tower is a separate scaffold bay with one flight per lift, standing in front of the facade scaffold and connected to it. Aluminium flights with integrated landings are common: one flight typically fills a 2.57 m bay and rises one lift of about 2 m. The parts are explained under scaffold stairway and stair tower.
- Hands free: you walk upright, hold the handrail and can carry a toolbox.
- Suitable for everyone: site managers, surveyors and clients who visit occasionally are far safer on stairs than on ladders.
- Space: it needs roughly one bay length by the tower width in front of the scaffold, which narrow plots or footways may not offer.
- Stability of its own: base jacks, sole boards, bracing, and connections to scaffold or building as the instructions prescribe.
- Same-direction or switchback flights: same-direction flights end one bay further along each time; switchback flights always arrive at the same point, useful when the transfer to the facade scaffold is fixed.
Every flight needs a stair guard rail, and each exit onto a working lift needs edge protection.
Other options
- External ladder tower: a narrow extra bay in front of the scaffold with ladders and landings. Keeps the working lifts free of hatches but needs space and its own bracing.
- Stair inside a wide scaffold: some systems allow a stair within a wide bay. Saves ground space, costs working area.
- Access from the building: a lift reached from a window or terrace. Never a substitute for access to all lifts, and only with a safe, gap-free transfer.
- Leaning ladder: acceptable only within narrow limits, for very low scaffolds and short jobs, secured at the foot and extending about 1 m above the landing point.
Ladder bay and stair tower compared
| Criterion | Ladder bay with hatch decks | Stair tower |
|---|---|---|
| Ground space | none extra | own bay in front |
| Material | one hatch deck per lift, ladders if not integrated | frames or standards, flights, rails, bracing, base |
| Erection effort | low | considerably higher |
| Carrying tools | poor | good for light loads |
| Occasional visitors | limited | well suited |
| Rescue | difficult through a narrow hatch | much easier |
| Typical use | houses, short duration, few users | taller scaffolds, long duration, many trades |
Where the access belongs
Access in the wrong place does not get used. Put it near the material store and the delivery point, not in front of windows or doors that need work, not where girders, canopies or balconies are, and centrally on long elevations so the walk is short in both directions. On a scaffold round a whole building, an access at a corner serves two sides. The foot of the access should not be in a traffic lane.
Worked example
A warehouse of 40 × 20 m with 10 m eaves is scaffolded on all four sides for new cladding, five lifts of 2 m each. The ring is 2 × (40 + 20) = 120 m long. With one access at a corner, the furthest point is 60 m away, over the planning figure. Two accesses at diagonally opposite corners cut the longest walk to 30 m and provide a second escape route. As a ladder bay, that means five hatch decks per access, ten in total, replacing ten ordinary decks. As a stair tower, it means five flights, frames for six levels, stair rails, bracing, base jacks and connectors. A practical mix: a stair tower on the side with the delivery area and material store, a ladder bay opposite. The scaffolding calculator gives the main scaffold; add the access afterwards from our range of ladders and stairs.
During erection, dismantling and after hours
Access is built with each lift, not at the end. As soon as a new lift stands, the hatch deck goes into the access bay or the next flight is hooked in, and the erectors use it themselves. On dismantling, the access comes down with its lift, never before.
After work, access invites intruders, and children climbing scaffolds in the evening are a real risk on housing and school sites. Remove or raise the lowest ladder and lock it away; close stair towers at the foot with a lockable gate or a fence panel. A warning sign belongs there too but does not replace these measures. Whoever arrives first in the morning opens the access and checks whether anything was moved overnight. Further measures are described in our guide to scaffold security against theft and trespass.