Mezzanine Floors for Commercial Buildings - Australian Standards Explained.
Mezzanine Floors for Commercial Buildings.
When building a mezzanine floor, Australian standards need to be met to ensure the legality and safety of the structure. The staircase is no exception to these rules. While there are seven [7] essential standards that a mezzanine floor (see below) must comply with to meet Australian standards, two of them, AS1657 and AS1428, specifically cover the regulations for staircases. The other standards are equally important. Let's explain below.
AS1657
AS1657 covers requirements for mezzanines, steel gangways and fixed platforms under 200m2. Structures that fall under this definition must:
have no more than 18 risers in a single-stair flight
have a tread height of no more than 190mm
include a balustrade height of at least 1m, with a 460mm gap between the top and middle rails
AS1428
AS1428 covers the same above structures that exceed 200m2 in floor area. The key requirements for structures falling under this category are:
Access paths, which include staircases, must be at least 1m wide
Your balustrade has to be continuous from the top to the bottom of the staircase
Tactile indicators must be included at the top and bottom of the stairs
Any gap in the balustrade must not be able to fit a 125m sphere through it.
What are the Australian Standards that apply to a mezzanine floor?
There 7 essential standards that need to be considered when constructing a mezzanine floor
AS1657 (Fixed platforms, walkways, stairways and ladders)
AS1428 (Design for access and mobility)
AS 1170 Vol 1 Part B1
AS1170 Loading Codes
AS 4100 Steel Structures
AS 4600 Cold-Formed Steel Structures
Fire compliance
How and why do these standards apply?
We have explained the standards below and a more in-depth guide regarding what these standards mean and how they apply based on your purpose for the mezzanine floor. Some of the critical standards and definitions to consider are:
1. AS1657 (Fixed platforms, walkways, stairways and ladders)
AS 1657 is a standard written for steel gangways and walkways where it is not considered as an additional floor level within the factory, and the mezzanine floor is not larger than 200m2.
Any mezzanine floor under 200m2 is classified as a standard mezzanine floor or raised storage area for storage.
AS1657 is the essential Mezzanine Floor Australian Standard that will apply to every mezzanine floor under 200m2 in size. The necessary conformance requirements include but not limited to are:
Tread heights not exceeding 190mm
No more than 18 risers in a single stair flight
Balustrade heights no lower than 1m (460mm gap between the top rail and middle rail)
2. AS1428 (Design for access and mobility)
This standard is essentially an upgraded version of the AS1657 standard only applies to a mezzanine floor exceeding 200m2 in size which the mezzanine floor than becomes classified not as a mezzanine floor but as a story within the building or a mezzanine floor built for the purpose of an office.
A mezzanine floor larger than 200m2 falls under the AS1428 standard as it is considered as effecting the floor space within the building such as paths of travel between exits, and entries of the building.
Some of the critical Australian standard considerations relating to a mezzanine floor when conforming to AS1428 include but not limited to are:
Tactile indicators at the bottom and top of the stairs.
If any area has a clearance height of less than 2m, tactile indicators must warn of the low clearance.
125mm sphere cannot fit through any gap on the balustrading or staircase.
Continuous balustrading from ground floor up to the mezzanine level.
Other standards that need to be considered but do not strictly apply to the mezzanine floor construction as such are;
Door handles less than 900mm above floor level.
Width of access paths must be minimum 1m internal (from balustrade to balustrade).
3. Steel Structure AS codes
This is moving into structural steel engineering territory however we have provided the 4 key standards that must be adhered to for compliance.
AS 1170 Vol 1 Part B1
AS1170 Loading Codes
AS 4100 Steel Structures
AS 4600 Cold Formed Steel Structures
4. Fire compliance
Fire compliance is an essential consideration for every project. There is no broad-brush rule as every building is different and must be considered on its own individual merits by a qualified fire engineer and building surveyor. However there are some important considerations such as minimum exit and entry distances from the mezzanine floor to the outside of the building, also door and access path widths.
Important things that are considered are the type of building you are putting the floor into i.e. Type A, B, C or very big building with sprinklers already in it.
Type A would typically be a building with a higher risk such as high rise, or high occupant buildings. An example of Type C is a building that has a lower risk and is, therefore, the least fire-resistant. A small building less than 2000m2 you likely will not need to worry about FRL’s (fire resistance levels).