Conversion between the "basic lift plus additional lifts" of the birdcage (full-area) scaffold and the rounding treatment above 5.2m: additional lifts = (indoor clear height - 5.2) / 1.2, with a remainder under 0.6m taken as half a lift (factor 0.5) or rounded, covering the differences between the railway, Shaanxi, Hunan and Jiangsu standards

Topic Positioning

The conversion between the "basic lift plus additional lifts" of the birdcage (full-area) scaffold: where 3.6m < indoor clear height ≤ 5.2m one basic lift is counted; above 5.2m each further 1.2m counts as one additional lift, the number of additional lifts = (indoor clear height - 5.2) / 1.2. This card summarises the rounding differences (a remainder under 0.6m counted as half a lift or rounded away), the quantity basis and the anti-double-counting points across the railway TB/T 10831-2024, Shaanxi, Hunan and Jiangsu standards.

Core Conclusions

1. The basic conversion framework (identical across the standards)

• Trigger: a birdcage scaffold is counted only where the height of ceiling plastering and decoration exceeds 3.6m (not counted within 3.6m).
• Basic lift: one basic lift where the indoor clear height lies between 3.6m and 5.2m (above 3.6m up to 5.2m).
• Additional lifts: above 5.2m, each further 1.2m counts as one additional lift; number of additional lifts = (indoor clear height - 5.2) / 1.2.
• Quantity basis: the net indoor area (horizontal projected area), with no deduction for columns, piers, attached chimneys and the like; Hunan words it as "the actually erected horizontal projected area, without deducting the areas of attached columns and free-standing columns"; every additional lift is billed layer upon layer on the same net area.

2. Rounding of the remainder above 5.2m (the key difference, at the 0.6m boundary) 1.2 x 0.5 = 0.6m; all the standards take 0.6m as the "half-step" boundary. They differ on whether a remainder under 0.6m counts as a half lift or is discarded:

• Half-lift system (railway TB/T 10831-2024, Shaanxi quota): the railway volume notes read "The birdcage scaffold is measured on the net indoor area; where the height is between 3.60m and 5.20m a basic lift is counted; above 5.20m each additional 1.20m counts as one additional lift; where the height is under 0.60m, one additional lift multiplied by a factor of 0.50 is counted". Shaanxi reads "Where the height lies between 3.6m and 5.2m a basic lift is counted; beyond 5.2m each further 1.2m counts as one additional lift; under 0.6m, one additional lift multiplied by a factor of 0.5 is counted. Formula: birdcage-scaffold additional lifts = (indoor clear height - 5.2) / 1.2m". Reading: every full 1.2m counts one whole lift; a remainder of 0.6m or more counts one lift; a remainder under 0.6m counts 0.5 lift.
• Rounding system (Hunan 2025 consumption standard for building and decoration works): the original text reads "Where the storey height exceeds 5.2m, each further 1.2m counts as one additional lift; the number of additional lifts = (storey height - 5.2m) / 1.2m, rounded to the nearest integer". Reading: a decimal of 0.5 or more (i.e. a remainder of 0.6m or more) is rounded up to one lift; under 0.5 (a remainder under 0.6m) is discarded.
• Worked examples (H = indoor clear height): H = 5.7m, (H-5.2)/1.2 = 0.4167 → half-lift system 0.5 lift, rounding system 0 lifts; H = 6.6m, 1.1667 → half-lift 1.5 lifts, rounding 1 lift; H = 7.0m, 1.5 → both systems 2 lifts; H = 7.9m, 2.25 → half-lift 2.5 lifts, rounding 2 lifts.
• Under the same storey height the two systems differ by at most 0.5 additional lift; the applicable treatment must be settled from the notes of the quota governing the project before pricing.

3. Special boundaries (they differ between standards and must not be transposed across regions)

• Jiangsu (consumption quota for building and decoration works): where the ceiling plastering height exceeds 3.60m, the birdcage scaffold is measured on the net indoor area without deduction for columns, piers and attached chimneys; the basic lift covers heights within 8m; above 8m each further 2m counts one additional lift, the result kept to an integer, decimals up to 0.6 discarded and above 0.6 rounded up. This differs from the 5.2m / 1.2m framework.
• Height datum of the birdcage scaffold: from the indoor floor (or floor-slab surface) to the ceiling or the soffit of the roof slab; sloping ceilings or roofs are taken at average height (Jiangsu wording).

4. Associated billing points (anti-double-counting)

• Where a birdcage scaffold is counted, the internal-wall decoration scaffold is not counted again: railway - "where the storey exceeds 3.60m and the ceiling requires plastering, painting, suspended ceilings and the like, a birdcage scaffold may be added, and the wall-finishing scaffold is not counted separately"; Hunan - "indoors, wherever a birdcage scaffold has been counted, no further decoration scaffold is counted for the internal wall finishes; only a scaffold-alteration charge is added on the vertical projected area of the wall".
• Distinguish the purpose: birdcage scaffolds for slab concreting follow the dedicated provisions (railway: for slabs concreted above 3.60m indoors, the birdcage-scaffold quota item applies multiplied by a factor of 0.30) and must not be mixed with decoration birdcage scaffolds.

Applicability Boundaries

• Applies to the basic-lift / additional-lift conversion and pricing take-off of birdcage scaffolds for ceiling plastering and decoration in building and decoration works; not to masonry or concreting scaffolds (which follow the rules of their own chapters).
• Trigger heights, lift boundaries and rounding factors (5.2m / 1.2m, 0.6m / 0.5, or 8m / 2m and the like) differ between regional and sectoral standards; cross-province and cross-sector projects must not transpose them; before pricing, check the volume notes and measurement rules of the quota governing the project.
• Additional lifts presuppose a counted basic lift; no additional lift arises where the indoor clear height is ≤ 5.2m.
• Rules for suspended cradles, internal-wall finishing scaffolds, composite scaffolds and other scaffold types are outside the scope of this card.

Further Reading

• Railway: TB/T 10831-2024 "Railway Works Budget Quota, Volume 10, Building Works", volume notes, section VI "Measurement Rules (3) Individual Scaffolds", item 5; items FY-440 (birdcage scaffold, basic lift, 3.6m < indoor clear height ≤ 5.2m), FY-441 (birdcage scaffold, additional lift per 1.2m), FY-442 (birdcage-type steel-pipe support).
• Hunan: "Hunan Consumption Standard for Building and Decoration Works" (2025 edition), scaffolding works notes (birdcage-scaffold conversion and scaffold-alteration charge; anti-double-counting clauses) and items A18-40, A18-41.
• Shaanxi: "Shaanxi Newly Compiled Consumption Quota (draft for comment)", scaffolding works measurement rules, item (6).
• Jiangsu: "Jiangsu Consumption Quota for Building and Decoration Works", scaffolding works measurement rules (the 8m / 2m treatment).