Oak Stairs: Slip Resistance, Nosings and Where the Waste Goes
Stairs are where a flooring specification is tested hardest. They carry a compliance requirement that the rest of the floor does not, they generate more waste than any other element, and they are the most visible piece of joinery in most houses.
Three things decide whether a stair detail works.
Slip resistance, and what D1 requires
Clause D1 of the New Zealand Building Code, Access Routes, sets slip resistance requirements so surfaces provide adequate traction. It is the one clause that applies to a stair and not to the floor it connects.
Our European oak has been independently tested by Independent Slip Testing Services in accordance with AS/NZS 4586:2004:
- Wet pendulum test: mean 39 BPN, Classification X
- Dry floor friction test: mean 0.48 COF, Classification F
Those are the classifications as tested. The report records them and draws no compliance conclusion, so the requirement for your stair, its location and its expected traffic needs confirming against D1 by whoever writes the specification. The full report is published as the Slip Resistance Test.
Where a higher classification is needed
Environment and use change the requirement. Wet or high-traffic commercial areas, entry foyers, cafés, retail floors and any stair likely to be exposed to moisture typically call for a W or P4 classification.
In those cases the answer is not a different floor. It is a compliant stair nosing or anti-slip treatment on the tread edge, which achieves the rating without compromising the material. This is the single most common oversight we see on hospitality and retail specifications.
Nosings, and where the waste comes from
Stair nosing in this market is typically supplied in 1.9 metre lengths. A standard staircase is around 1.0 to 1.1 metres wide, which means every 1.9 metre length yields one tread and a substantial offcut that is paid for and discarded.
Our nosing is made in 2.2 metre lengths to match our 2.2 metre boards. At that length a single piece covers two standard treads, so the number of pieces halves and the offcut largely disappears.
Nosing is custom made in every colour in the range, so the tread edge matches the floor rather than approximating it. The same 2.2 metre logic applies to the boards themselves: a 2.2 metre board covers a standard stair width outright, which means fewer joints, a cleaner run up the flight, and less time on site cutting.
Wrapping a stair properly
A 20mm profile is what makes a genuine stair wrap possible. Thinner boards force either a separate tread product or a visible transition at the nosing, and both read as a compromise on an open stair.
At 20mm the tread, riser and nosing can be detailed as one continuous material, with 240mm width available where a wide tread suits the design. The detailing sequence is in the Installation Instructions, and the reasons the dimension matters elsewhere in the build are in why 20mm is the New Zealand standard.
What to check before you specify a stair
- Will the stair be wet or high traffic? If yes, specify a compliant nosing or anti-slip treatment from the outset.
- What length is the nosing supplied in, and how many treads does one length actually yield?
- Is the nosing available in the floor colour, or is it a stock profile that will need to be matched?
- Is the board thick enough to wrap, or will a transition be visible at every tread?
The slip resistance test and the installation instructions are in Resources. Stair work in completed projects is documented under Projects.
To see a wrapped stair rather than read about one, visit the Christchurch, Auckland or Queenstown studio, or book a design consultation.
