# Tie Column Quantity Calculator

Tie column count, concrete, formwork and rebar from wall and section.

- Page: https://jianzhujisuan.com/en/tie-column
- Category: Masonry (https://jianzhujisuan.com/en/c/masonry)
- Chinese version: https://jianzhujisuan.com/zh/tie-column.md
- Data checked: 2026-10-25

## Quick result

With the default inputs (Wall length 20 m, Column spacing 4 m, Column height 3 m, Section width 240 mm, Section depth 240 mm, Toothing factor 1.15): **Tie columns 6 bars**

## Inputs

| Parameter | Type | Default | Unit | Note |
|---|---|---|---|---|
| Wall length | number | 20 | m |  |
| Column spacing | number | 4 | m | Usually not more than 4 m; required when the wall exceeds 5 m |
| Column height | number | 3 | m |  |
| Section width | number | 240 | mm |  |
| Section depth | number | 240 | mm |  |
| Toothing factor | number | 1.15 | — | Multiply the section by 1.1-1.2 for toothings |

## Formula

- **Count**: n = floor(wall length ÷ spacing) + 1
- **Concrete per column**: V = section × height × toothing factor
- **Formwork**: A = n × 2 × (b + h) × height
- **Main bars**: L = n × 4 × (height + 2 × 0.5 m)
- **Stirrup**: 2(b−2c) + 2(h−2c) + 2 × 11.9d

## Worked example

A 20 m wall at 4 m spacing with 240×240 columns 3 m high: 6 columns, 1.19 m³ of concrete, 17.28 m² of formwork and about 93.8 kg of reinforcement — 78 kg per cubic metre.

## Questions

### When are tie columns mandatory?

Common rules: a wall longer than 5 m or twice the storey height needs one at mid-length; over 8 m or 2.5 times the height, add more. Also at unconstrained wall ends, both sides of openings, parapets and stair corners. The purpose is to break long walls into segments so they cannot buckle out of plane.

### Why cast the column after the wall?

The column works compositely with the masonry, gripping it through the toothings. Casting first leaves a flat joint relying only on mortar bond with almost no shear capacity — as good as no column at all. The code therefore requires wall first, toothings left, column cast later, with a 50-100 mm gap at the head filled with non-shrink mortar.

### How is toothing concrete counted?

Multiply the section by 1.1-1.2. The toothings make the actual section larger than the rectangle — 60 mm deep, five courses in and out, adding roughly 10-20% volume. The precise method is (width + tooth depth) × thickness × height, but the factor is what settlements normally use.

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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.