Nosing
A stair nosing is the projecting front edge of a tread. NCC balustrade heights and handrail heights are measured from the nosing line, not the floor.
Ask Chalkline about this →The nosing is the projecting front edge of a stair tread, the part your foot lands on first when walking up or down. It typically overhangs the riser below by 15 to 25 mm on timber stairs.
Nosings matter for compliance because the NCC measures balustrade heights and handrail heights from the nosing line, not from the floor. Under the ABCB Housing Provisions Part 11, a barrier along a stairway must be not less than 865 mm above the nosings of the treads (clause 11.3.4(2)(a)), and a handrail must be not less than 865 mm above the nosings (clause 11.3.5(1)(c)). Measuring from the floor instead of the nosing line is a common site error that causes balustrades to read as under-height at inspection.
On external stairs, nosing edges are also the primary slip-resistance location: AS/NZS 4586 P-ratings apply to the tread surface measured at and near the nosing.
Also known as: stair nosing, tread nosing.
Category: Stair construction and compliance.
Related
- NCC stairs, balustrades and handrails: full Part H5 compliance detail
See also
- Tolerance: workmanship tolerance in a building context
Last updated: 2026-05-07. Verified: 2026-05-07. Quarterly review for currency.