Stringer (stairs)
A stringer is the inclined structural member up each side or centre of a stair that treads and risers fix to; marking it out in one pass keeps risers uniform.
Ask Chalkline about this →A stringer is the inclined structural member running up each side (or up the centre) of a stair that the treads and risers fix to. Marking it out accurately, in one pass, is how a builder keeps the risers uniform within the tight tolerance the NCC allows.
The stringer carries the stair from floor to landing or floor at the stair pitch. Two common forms:
- a cut (open) stringer, where the treads sit on triangular cut-outs along the top edge, and
- a housed (closed) stringer, where the treads and risers are housed into routed grooves and often wedged.
Because every step is positioned by the stringer set-out, getting the stringer right is what delivers uniform risers and goings. The NCC requires the risers and the goings to be uniform within a small tolerance (about 5 mm) across a flight, and uneven steps are both a code failure and a genuine trip hazard.
For a builder the practical point is to set the stringer out carefully and in a single pass, a pitch board or stair gauge helps, because that one set-out fixes every riser and going. An error repeated up the stringer gives a non-uniform stair that fails stair geometry and has to be rebuilt. Account for the finished floor levels at the top and bottom when you mark the first and last risers, that is where uniformity is most often lost.
Also known as: Stair string, carriage (centre stringer).
Category: Stairs / Construction.
Related
See also
References
- Stair geometry (Chalkline) (verified 2026-06-01)
Last updated: 2026-06-01. Verified: 2026-06-01. Quarterly review for currency.