When should I use a stairway tower instead of ladders?

Stairway towers should be used when: the scaffold will be used by many workers (more than about 10 people regularly), workers need to carry tools or materials up (you cannot carry items safely on a ladder), the scaffold height exceeds 9m, or the scaffold will be in use for extended periods. Under CDM regulations, the access must be suitable for the number of users.

How often are rest platforms needed in a stair tower?

BS 5395-1 recommends a rest platform at least every 4.5m of vertical rise. The rest platform should be at least 1.2m × the stair width and allow the direction of travel to reverse. For scaffold stairway towers, this typically means a landing every 2 flights, where each flight rises approximately 2.0-2.5m.

What are the dimensions of a standard stair tower?

Typical scaffold stair tower dimensions: 1.4m wide × 2.5m long in plan. This accommodates a 700mm clear stair width with a 180° turn at each landing. Some manufacturers offer narrower (1.2m × 2.0m) or wider (1.8m × 3.0m) options. The tower must be tied to the main scaffold or the building at each landing level.

What are the requirements for scaffold ladder access?

For ladder access within scaffolds: ladders must extend 1m above each landing platform. Trap doors must be provided in the platform for internal access. Maximum 6m between ladder access points. Ladders should be at 75° (4:1 ratio). Rungs must be uniformly spaced. Ladder access is only suitable for low-use scaffolds with few workers.

Do stair towers need separate foundations?

Stair towers should be founded on the same base as the main scaffold — typically sole plates on firm ground. If the stair tower is freestanding (not attached to the main scaffold), it needs adequate bracing and ties to the building. The base must support the concentrated loads from the stair tower standards, which carry the weight of all the stairs, landings, and users.

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Scaffold Access Stairway Calculator — Tower Dimensions & Rest Platforms

Calculate scaffold stairway tower requirements: tower dimensions, number of flights, rest platforms at 4.5m intervals, handrails, and alternative ladder access.

Total Height

Height from ground to highest working level

Access Type

Stairway for high-use, ladder for low-use scaffolds

How We Calculate This

This calculator determines scaffold access requirements — either a stairway tower or ladder access — based on the scaffold height and usage.

Stairway tower design

Flights: Each flight rises approximately 2.0m with a half landing
Rest platforms: Required every 4.5m vertical rise (BS 5395)
Tower size: Typically 1.4m × 2.5m in plan
Handrails: Both sides of stairway, continuous

Frequently Asked Questions

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Last updated: March 2026

All calculations are estimates. Verify with your supplier.