Stairs for Mezzanine Floors – A Simple Guide.
Mezzanine Floor Stairs can be confusing – Do you work with the National Construction Code, AS1428.1-2009 or AS1657-2018?
National Construction Code – General Guidelines
1. Risers and Goings – Risers must be between 115mm and 190mm. Goings must be between 240mm and 355mm. A combination of 2 x Risers and 1 x Going must be between 550mm and 700mm. If the room is non-habitable and not frequently accessed then Risers can be between 130mm and 225mm, Goings can change to 215mm to 355mm. The combination of 2 x Risers and 1 x Going changes to 540mm to 700mm – A whopping 10mm difference!
2. Treads and Risers – Gaps between treads must be small enough to ensure a 125mm sphere doesn’t pass through. The largest and smallest riser in a flight of stairs must not exceed 10mm. You can’t have less than 2 x Risers in a Flight and a maximum of 18 x Risers.
3. Balustrades/ Handrails – Gaps between Balustrades must be small enough to ensure a 125mm sphere doesn’t pass through.
AS1428.1-2009 – Offices, Public Spaces
1. Risers and Goings – Risers and Goings must be as per the National Construction Code (NCC)
2. Treads and Risers – Risers must be opaque (not see through) and enclosed. Nosings are required on Treads.
3. Balustrades/ Handrails – Gaps between Balustrades must be small enough to ensure a 125mm sphere doesn’t pass through. The Top Rail must be continuous and have J-Returns on each end. Tactile Indicators are required at the top and bottom.
AS1657-2018 – Fixed Platforms, Walkways, Stairways and Ladders
1. Risers and Goings – Risers must be between 130mm and 225mm. Goings must be between 215mm and 355mm. A combination of 2 x Risers and 1 x Going must be between 550mm and 700mm. If the room is non-habitable and not frequently accessed then Risers can be between 130mm and 225mm, Goings can change to 215mm to 355mm. The combination of 2 x Risers and 1 x Going changes to 540mm to 700mm – If you have actually been reading this, you have probably picked up on the fact these measurements are the same as a non-habitable room in the National Construction code!
2. Treads and Risers – Risers and Goings must be within a +-5mm Tolerance. The tread nosing must be visible against the background – Aka you need nosings.
3. Balustrades/ Handrails – A handrail is required on the open side of a Staircase. If the width exceeds 1000mm you need a handrail both sides. A top and mid rail is required and you need to ensure your hand can slide across the whole length. Toe board is required only on landings and not the staircase.
Stair Dimensions
Below are two tables showing the dimension of a typical staircase up to the maximum of 18 x Risers. Custom Stringers based on 190mm Risers and 175mm Risers. These suit AS1428.1-2009 and the National Construction Code. AS1657-2018 are typically custom designed to minimise the stair footprint.
TLDR;
If you can design your Staircase to AS1428.1-2009, you will have all bases covered in terms of certification as it exceeds/ encompasses the National Construction Code as well as AS1657-2018. The problem with that is that it’s also the most expensive staircase – So if you don’t have public access or your Mezzanine isn’t used all the time then we should be able to use AS1657-2018 as the standard for your project, which saves you money whilst also ensuring you have a quality staircase that still meets the relevant standards. Feel free to contact our team on 1300 678 188 or estimating@kitmezzanines.com.au if you’d like any further information or want to discuss a project.
