Stair Core Calculator

Footprint sizing for an enclosed stair shaft — dog-leg & straight flights

STD NCC 2022 DTS

UNITS millimetres

REV —

Inputs

Tread depth — going (G)

Nominal wall thickness (shaft walls)

Floor-to-floor height (FFL → FFL)

Riser count (↻ seeded from target)

Target riser height (drives count)

Configuration

Storeys served (>1 = entry-side landing)

no.

Clear stair width

Well gap

Landing depth (turn / arrival)

Overall core footprint

— × —

Compliance — NCC 2022 (DTS)

Stair geometry

Core dimensions

Setout drawings — plan & section

Dog-leg footprint = flight run + half-landing, by (2 × clear width + well gap), measured inside the shaft. For a continuous core (storeys > 1) a floor landing of the same depth is added at the entry side, since the flights from below and above meet and turn at every intermediate level — internal length becomes floor landing + flight run + half-landing. Wall thickness is added to all four sides for the overall figure.

Check before use. Defaults reflect NCC 2022 DTS limits — going 250–355, riser 115–190, 2R+G of 550–700, ≤ 18 risers per flight. These are not adjusted for building class, fire-isolation pressurisation, handrail/ balustrade encroachment, structural slab edges or finishes thickness. Confirm against the current NCC and your project class. Not a substitute for a documented stair detail.