# Ringlock Scaffold Calculator (by component)

Ringlock take-off by component: standards, ledgers, braces and bases, in pieces and tonnes.

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

## Quick result

With the default inputs (Building length 30 m, Building width 14 m, Height 24 m, Bay length 1.5 m, Transom spacing 0.9 m, Lift height 1.5 m, Rows of standards Two rows, Decking levels 2 levels): **Total ringlock weight 27.86 t**

## Inputs

| Parameter | Type | Default | Unit | Note |
|---|---|---|---|---|
| Building length | number | 30 | m | Long side of the building; the scaffold on all four sides is worked out automatically from length and width |
| Building width | number | 14 | m | Short side of the building; together with the length it sets the scaffold quantity, with extra continuous braces at corners |
| Height | number | 24 | m | At 24 m and above braces tighten from 4 bays to 3; 50 m and above needs expert review |
| Bay length | number | 1.5 | m | Stock sizes 0.6-2.4; 2.4 is the longest ledger made |
| Transom spacing | number | 0.9 | m | Usually 0.9 or 1.2; 2.4 maximum |
| Lift height | number | 1.5 | m | 1.5 or 2.0 only, since braces are only made in those two rises |
| 3.0 m standard | select | In stock | — |  |
| 2.5 m standard | select | In stock | — |  |
| 2.0 m standard | select | In stock | — |  |
| 1.5 m standard | select | In stock | — |  |
| 1.0 m standard | select | In stock | — |  |
| 0.5 m standard | select | In stock | — |  |
| Rows of standards | select | Two rows | — | Normal facade work is two rows. Three or four rows widen the platform; frame width = (rows - 1) x transom spacing |
| Decking levels | number | 2 | levels | Fully decked working levels, usually 2 |

## Formula

- **Facade area**: S = (length + width) x 2 x height (m x m = m²); the scaffold wraps all four sides and is taken off as one straight run; the frame's own width (transom spacing) is not part of the facade area
- **Bays**: n = ceil[(length + width) x 2 ÷ bay length]
- **Rows of standards**: Use 2 rows for ordinary facade work. Three or four rows widen the platform and change only four quantities: standards, longitudinal ledgers, transoms and adjustable bases
- **Frame width**: B = (rows - 1) x transom spacing (m); the transom spacing is the gap between adjacent rows, not the width of the frame
- **Standards**: N = (bays + 1) x rows of standards (2 by default)
- **Standard make-up**: Complete-knapsack over the ticked lengths only (six stock sizes 3000/2500/2000/1500/1000/500, each can be marked out of stock), lightest make-up with total length within [height-0.3, height+0.5]; remainder taken by the base jack
- **Standard splices**: Splices per leg = lengths - 1; total = standards x (lengths - 1), staggered by at least 500 mm
- **Ledger levels**: n = floor(height ÷ lift) + 1, including the bottom sweep and the top level
- **Longitudinal ledgers**: N = levels x bays x rows, one per row
- **Transoms**: N = levels x (bays + 1) x (rows - 1); one links each pair of adjacent rows, so two rows take one, three take two, four take three
- **Brace interval**: 3 bays where height is 24 m or more, otherwise 4 bays (clause 6.3.5 item 2)
- **Brace columns**: N = floor(bays / interval) + 1; the run must start with a brace, so ceil is wrong
- **Vertical braces**: N = columns x floor(height / lift). This does not rise with the number of rows: clause 6.3.5 covers the outer face of a two-row scaffold only, so bracing the inner face or the middle rows of a three- or four-row frame is a method-statement decision
- **Adjustable bases**: N = number of standards; a facade scaffold uses bases, not head jacks
- **Ties**: N = [floor(bays / 3) + 1] x [floor(lifts / 2) + 1]
- **Weight**: W = sum of quantity × unit mass from Table A.0.1

## Worked example

A 30 m by 14 m building wrapped on all four sides, 24 m high, 1.5 m bays, 0.9 m transoms, 1.5 m lifts: 59 bays, 120 standards (each eight 3000 mm lengths), 17 ledger levels, 2,006 longitudinal ledgers and 1,020 transoms, and because 24 m trips the three-bay rule, 20 brace columns x 16 lifts = 320 braces plus 120 adjustable bases — about 27.9 t, or 13.2 kg per m² of facade. With three rows: 180 standards, 2,040 transoms, about 42.3 t; with four rows: 240 standards, 3,060 transoms, about 56.7 t — three rows is not 1.5 times and four is not 2 times, because the transoms double and treble.

## Questions

### How do I work out a three- or four-row scaffold, and how far off is it from two rows?

The number of rows changes only four quantities: standards = (bays + 1) x rows; longitudinal ledgers = levels x bays x rows, one per row; transoms = levels x (bays + 1) x (rows - 1), one linking each pair of adjacent rows, so two rows take one, three take two and four take three; adjustable bases = number of standards. Vertical braces and ties do not change with the number of rows. So three rows is not 1.5 times and four rows is not 2 times: at 88 m long, 24 m high, 1.5 m bays, 0.9 m transoms and 1.5 m lifts, two rows give 120 standards and 27.86 t, three rows give 180 standards and 42.29 t (1.52 times), and four rows give 240 standards and 56.72 t (2.04 times) — the difference comes from the transoms doubling and trebling. One more thing that catches people out: the transom spacing is not the frame width. Frame width = (rows - 1) x transom spacing, so three rows at 0.9 m transoms give a 1.8 m wide platform. A final caution: every construction clause for working scaffolds in section 6.3 of JGJ/T 231-2021 is written for two rows (lift, staggered first lift, access openings and vertical braces all say two-row), so three and four rows go beyond the standard construction rules and need a specific method statement; whether the inner face or the middle rows need braces is not addressed, so that has to be added by hand on top of what this tool gives.

### At 24 m exactly, is it four bays or three?

At 24 m exactly, use three. Clause 6.3.5 item 2 of JGJ/T 231-2021 reads that where the scaffold height is 24 m or above, a vertical brace shall be provided at intervals of not more than three bays. The Chinese wording includes the boundary value, so 24.0 m itself takes three-bay spacing rather than waiting for 24.1 m. Four independent sources agree word for word, including two municipal housing-authority hazard catalogues and the standard text itself. The cost of getting it wrong is concrete: a 30 m by 14 m building at 24 m gives 15 brace columns (240 braces) at four bays against 20 columns (320 braces) at three, a shortfall of 80 braces and roughly 460 kg. The same 24 m is also the trigger for high-risk temporary works under MOHURD circular No. 31 of 2018, so one height trips two separate rules and both include the boundary.

### Why can't I just multiply tube length by mass per metre?

Because ringlock members carry a connector at each end, so the weight is not the tube weight. Φ48.3x2.5 tube alone is indeed 2.82 kg/m, but ledger B-SG-1200 is nominally 1200 mm, actually 1152 mm, and tabulated at 3.60 kg — a per-metre estimate gives 3.38 kg and understates by 6%. Braces diverge further: B-XG-1500x1500 has an actual length of 2004 mm and weighs 5.76 kg, while 2.82 kg/m gives 5.65 kg, and its horizontal projection bears no simple relation to its diagonal length anyway. Procurement is by piece and by type, quotations and site acceptance are by type, so the take-off must be by type too. This is the essential difference from coupler scaffolding: coupler tube is plain tube and can be estimated per metre, whereas ringlock members are finished components that can only be looked up.

### What counts as high-risk, and when is expert review needed?

A ground-bearing tube scaffold 24 m or higher is high-risk temporary works and needs a specific method statement that has been reviewed and approved; 50 m or higher is above-scale high-risk and requires expert review. The basis is the two annexes to MOHURD circular No. 31 of 2018, annex 1 for the high-risk scope and annex 2 for the above-scale scope. Two things to note: both thresholds are inclusive, and a ringlock system does not escape the method statement on the grounds of higher capacity — the classification turns on height and form, not member strength. Building without the required review carries, under Order 37 article 34, a correction notice, a fine of CNY 10,000 to 30,000, a 30-day suspension of the safety production licence, and a further CNY 1,000 to 5,000 on the responsible person.

### What is the difference between an adjustable base and a head jack?

A facade scaffold needs adjustable bases only, not head jacks. A base jack sits under the standard, transfers load to the ground and adjusts height; a head jack sits on top of the standard and is used on shoring scaffolds to carry primary beams and beam soffit formwork. They are not interchangeable and their masses differ: standard B-XT-600 base is 3.89 kg and B-XT-500 is 3.53 kg, while B-ST-600 head jack is 4.74 kg and B-ST-500 is 4.38 kg. Heavy-duty Z types are heavier again, Z-XT-600 at 6.15 kg and Z-ST-600 at 7.60 kg. Including head jacks in a facade take-off overstates the order; omitting them from a shoring take-off leaves the top level with nothing to adjust when the beam soffit goes on.

### Our depot has no 3 m standards. Can I still use this?

Yes — set the 3.0 m standard switch to 'Not stocked' and leave the other five ticked. Each of the six lengths has its own switch, so switch off exactly what your depot lacks rather than fitting a preset set. First, the facts: a 3.0 m standard is a standardised component. Table A.0.1 of DB11/T 2100-2023 lists B-LG-3000 at 14.65 kg, and depots in Tianjin and Langfang publish 0.5 to 3.0 m as their normal range. So the length does exist; what varies is what each depot stocks, and plenty stop at 2.5 m, which is entirely normal on site. The cost of losing the 3.0 m length is more splices. At 24 m the full set gives eight lengths and seven splices per leg; with 2.5 m as the maximum the make-up is 2.5x8 + 2.0x2, ten lengths and nine splices, so 120 standards carry 240 extra splices. One thing worth getting right before ordering: the connecting collar is **not a separate fitting** — it is welded to one end of the standard and is part of the component (clause 2.1.11), so extra splices do not mean renting extra collars; what you do need is the standard connecting pin, one per splice. The real difficulty is staggering. Clause 6.3.2 requires splices to be staggered level by level with at least 500 mm between adjacent ones, and the commentary to clause 5.2.1 of DB11/T 2100-2023 spells out why: with every splice on one level, a horizontal force puts some standards into tension and makes them buckle. Going from seven splices to nine leaves less room to stagger, so the bottom lift has to alternate standard lengths rather than splicing every standard at the same height. If the depot cannot even supply 2.5 m, change depot rather than building up from 1.5 m lengths — splices that dense compromise the integrity of the frame.

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