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Staircase concrete volume and how it splits up

Waist slab, steps and landing as separate volumes, and why the pour is usually smaller than people expect.

The engineering question

A staircase needs formwork more than it needs concrete. How do you get the volume, and what drives the shuttering quantity?

Worked example

The figures below were produced by running the Staircase Concrete Volume Calculator with the same inputs — during the build, from its authoritative engine.

Results
Total concrete volume 1.404 m³
Waist slab volume 0.7608 m³
Steps volume 0.4704 m³
Landing volume 0.1728 m³
Sloping slab length 5.283 m
Flight rise 2.8 m
Flight going 4.48 m
Assessment Flight rise 2.80 m over 4.48 m going; slab ≈ 5.3 m long → ≈ 1.40 m³ of concrete (waist 0.76 + steps 0.47 + landing 0.17).
  1. The sloping slab length is the flight rise and going taken together.
  2. Waist volume is length × thickness × width; steps add a triangular prism per riser.
  3. The landing is added separately, and often at a different thickness.

Sanity check

16 risers at 175 mm rises 2.8 m and goes 4.48 m. If the geometry looks wrong, check that treads were not entered as clear opening rather than going.

Tools for this problem

These are the EngiMetric calculators that compute the numbers in this topic. Each one shows its formula, its units and its limits rather than returning a bare result.

References & standards

  • BS 8500-2 — construction of reinforced concrete stairs
  • EN 1992-1-1 — design of concrete staircases

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