# Scaffold Dismantle Sequence Calculator

Lifts to strip, allowable step height, and where the raking props start.

- Page: https://jianzhujisuan.com/en/scaffold-dismantle
- Category: Temporary Works (https://jianzhujisuan.com/en/c/temporary-works)
- Chinese version: https://jianzhujisuan.com/zh/scaffold-dismantle.md
- Data checked: 2026-10-25

## Quick result

With the default inputs (Scaffold height 20 m, Lift height 1.8 m, Bay length 1.5 m, Building perimeter 200 m): **Lifts to dismantle 12 lifts**

## Inputs

| Parameter | Type | Default | Unit | Note |
|---|---|---|---|---|
| Scaffold height | number | 20 | m |  |
| Lift height | number | 1.8 | m |  |
| Bay length | number | 1.5 | m |  |
| Building perimeter | number | 200 | m |  |

## Formula

- **Lifts = ceil(height ÷ lift height)**: 
- **Max step = 2 × lift height (add ties beyond this)**: 
- **Prop level = about 6.5 m (JGJ 130 7.4.3)**: 
- **Prop lift = ceil(6.5 ÷ lift height)**: 
- **Ties = ceil(perimeter ÷ (3×bay)) × ceil(height ÷ (3×lift))**: 

## Worked example

200 m perimeter, 20 m high, 1.8 m lifts, 1.5 m bays: 12 lifts to strip. Where two sections differ by more than 3.6 m, extra ties are required. At the fourth lift from the bottom (7.2 m elevation, roughly 6.5 m of frame left) temporary raking props go in before the ties at that level come out. 45 ties per row over 4 rows gives 180, and every one must come out lift by lift with the frame.

## Questions

### Why can't the ties come out first?

Ties are the only members that transfer horizontal load into the structure - they give the scaffold its wind and overturning resistance. Strip a whole floor or several floors of ties and the frame becomes a free-standing set of tubes; self-weight plus the crew and stacked material on it is enough to topple it. Investigation reports into dismantling collapses repeatedly cite exactly this: the ties were removed a floor or more ahead of the frame, so it lost its restraint. That is why the code makes ties-out-with-the-lift a mandatory requirement.

### Why prop the frame at about 6.5 m, of all heights?

Ties are densest at the top and get scarcer as you strip downwards, so restraint falls away. When only the last full-length standard is left, roughly 6.5 m, that stub has no weight of frame above it and almost no ties left - which is the least stable it will ever be. The code therefore requires temporary raking props from the outside first, then the ties at that level. Props are normally set at 45 to 60 degrees to the ground, footed on firm bearing.

### Does dismantling need a method statement?

Yes. Clause 7.4.1 requires dismantling to follow an approved method statement, and four things before starting: check the coupler connections, ties and bracing against the design; revise the sequence and measures in the method statement in the light of that check and get it approved; brief the crew; and clear debris from the scaffold and obstructions from the ground. A named person must direct the work. Land-based tubular scaffolds 24 m and above are classified as high-risk works, so the statement needs sign-off from the contractor's technical lead and the chief supervising engineer.

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Generated by BuildCalc. All calculations run in your browser; no data is uploaded. Formulas follow national standards and common trade practice; local codes govern.