Tie Column Quantity Calculator
Tie column count, concrete, formwork and rebar from wall and section.
Inputs
Result
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 |
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.
FAQ
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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Results are estimating aids only and are not a design basis. Construction and final accounts must follow the drawings, the applicable standards and an approved method statement. Anything affecting structural safety, shoring or falsework must be checked by a suitably qualified engineer.