AS 3959:2018 Bushfire Construction Standard: BAL Ratings and Building Requirements

Standards Australia · Published 2018 · Active

Your design, construction, and installation of fixed platforms, stairways, walkways, and ladders must be compliant the AS 1657 Standard of 2018. This is Australia’s primary framework that sets minimum requirements for fixed access and egress structures. Assure you are familiar with its specifications, because without it, you will not be given a building permit. All fixed structures must adhere to AS 1657:2018 to guarantee workplace safety standards are upheld, promoting safety and risk management.

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📖 What Is AS 1657:2018?

✦ KEY TAKEAWAYS

• ✓ Sets minimum safety requirements for fixed platforms, walkways, stairways and ladders in workplaces.
• ✓ Issued in 2018 with major revisions from the 1992 edition; current active version.
• ✓ Excludes portable ladders, scaffolding, domestic stairs and specialised systems like lifts.

The AS 1657 2018, titled ‘Fixed Platforms, Walkways, Stairways and Ladders - Design, Construction and Installation’, was issued in 2018 with major revisions from the 1992 edition. It is the primary Australian Standard that sets out the minimum safety requirements for fixed access systems and egress structures in workplace settings. The Standard provides requirements for the design, construction, installation, and use of platforms, walkways, stairways, and fixed ladders that are commonly found in factories, warehouses, water treatment plants, and construction and maintenance environments.

AS 1657:2018 is designed with the key purpose to promote better safety for everyone, increased durability, risk mitigation, and fewer accidents. It is important to note, though, that the AS 1657 2018 does not cover portable ladders (AS/NZS 1892 series), temporary access systems (scaffolding), public access stairs and walkways, domestic stairs and ladders and specialised systems (lifts or escalators).

📖 Scope and Application of AS 1657:2018

✦ KEY TAKEAWAYS

• ✓ Applies to industrial facilities, commercial buildings and non-domestic workplaces.
• ✓ Used by structural engineers, WHS managers, designers and building contractors.
• ✓ Enforced through WHS Regulations and the National Construction Code (NCC).

AS 1657 2018 sets load requirements, dimensional limits, and material specifications that apply to fixed access structures typically used in industrial facilities, commercial buildings, and other non-domestic workplaces. The Standard is used by structural engineers, workplace designers, WHS managers and building contractors to assure safe movement and access, protection from falls, and consistent engineering and safety design. Its use is required when access is needed for the operation of equipment, maintenance and servicing, and inspection tasks. It is typically applied through WHS regulations and NCC, which means that designers and builders are expected to comply with its requirements.

📖 Stairway Design Requirements

✦ KEY TAKEAWAYS

• ✓ Stair pitch must sit between 20° and 45° (preferred range 30° to 38°).
• ✓ Risers 130–225mm, treads 215–355mm, minimum stairway width 600mm.
• ✓ Handrails required on at least one side, minimum 900mm high.

AS 1657:2018 sets key dimensional requirements like the angle of inclination, maximum rise, minimum going, and minimum stairway width. The stair pitch or angle must generally be between 20° and 45° to the horizontal, with a preferred range between 30° and 38°. If the angle is steeper, a ladder may be required instead.

The riser height is typically between 130 and 225mm, while the tread depth (going) is set between 215 and 355mm. Steps must be uniform throughout the flight, as uneven steps are a major trip hazard and not permitted. Treads and nosing must be slip-resistant.

The stairway width should be at least 600mm. Handrails are required on at least one side of the stairway, and need to be a minimum of 900mm high, 1,000mm for high-risk applications. They should also be continuous along the flight and easy to grip.

Other features the Standard describes include landing, guardrails and edge protection, headroom, and structural and load requirements.

Handrail and Guardrail Specifications

According to the AS 1657 Standard, stairways should have a top rail for primary protection, a mid rail for gap protection, and a toe board where needed. The top rail must be located between 900 and 1,100mm vertically above the nosing of the stair treads. Where there is a significant fall risk, the minimum should be increased to 1,000mm as this is the main barrier preventing falls.

The mid rail must be installed between the top rail and the walking surface. It has to be placed in a way that no gap is large enough for a person to fall through. The toe board (or kick plate) needs to be at least 100mm high, and is required when there is a risk of objects falling from a platform or walkway onto people or equipment below.

Guardrails and handrails are required on at least one side of the stairs, but on both sides if the stairs are wide or if there is a risk of falling. Rails must be securely fixed to the structure with bolts that are strong enough to handle applied forces. They must be able to resist approximately 0.6kN horizontal force (outward push) and 0.4kN vertical force (downward load). Loads must be resisted without failure and without excessive deflection. The system must remain stable and functional.

📖 Fixed Ladder Requirements

✦ KEY TAKEAWAYS

• ✓ Rung spacing 250–300mm; minimum width 375mm; rungs must support 1.5kN.
• ✓ Vertical ladders 75°–90°; inclined ladders 60°–75°.
• ✓ Maximum unbroken height of 6m; cages required above 3m.

AS 1657 covers rung spacing, ladder angles, clearances, load, rest platform, and cage requirements for permanently fixed ladders used for industrial and workplace access, including vertical and inclined ladders.

Rung spacing should be between 250mm and 300mm, consistent throughout the ladder. The minimum width is set at 375mm between side rails. Wider ladders improve safety, but they must meet minimum clearance specifications. Rungs should withstand a minimum load of 1.5kN, simulating a person standing on the rung. Vertical ladder angles should be set between 75° and 90°, while inclined ladder angles have to be between 60° and 75°. Stairs should be used if the angles are less steep than this.

A clearance of at least 150mm is necessary behind the rungs. Side clearance must be enough so users don’t hit adjacent structures. Ladders must extend 900mm or more above the landing, or provide handholds.

Tall, vertical ladders need rest platforms with guardrails and safe access. The maximum ladder height without a break cannot exceed 6m. Ladder cages are commonly used for ladders over 3m, while very tall ladders (above 6m) require multiple platforms and fall-arrest systems.

📖 Platform and Walkway Requirements

✦ KEY TAKEAWAYS

• ✓ Minimum 600mm width for walkways and working platforms.
• ✓ Must support a Uniform Distributed Load of 2.5kPa for general industrial use.
• ✓ Edge protection required: top rail 900–1,000mm, mid rail and 100mm toe board.

The AS 1657 2018 Standards sets essential requirements for platform and walkway requirements, covering minimum width, working platforms, and access platforms. Walkways and working platforms need a minimum 600mm width to allow safe movement of workers, although platforms are often wider depending on use. Access platforms are sized based on function but are typically over 600mm. Many designs use 800–1,000mm for comfort and safety.

Platforms and walkways must support a Uniform Distributed Load (UDL) of around 2.5kPa for general industrial use. Their surfaces must be slip-resistant, durable, and suitable for the environment. Open mesh decking is generally preferred as it allows light and air to pass through while simultaneously providing drainage for rain, liquids, and debris. It’s commonly used for outdoor platforms and industrial plants. However, the openings must not exceed 45mm. If there’s concern of objects falling through the mesh, you must either use a tighter mesh (<15mm) or a solid decking.

Solid deckings prevent falling objects and contaminants from falling to lower levels and must include anti-slip treatment like coatings, patterns, or strips. However, solid deckings can accumulate water and debris, which can potentially become a slip hazard if not managed. It is crucial to consider the environment and its risks to decide which platform decking is required.

Edge protection or guardrails are required where there is a risk of falling. It must feature a top rail between 900 and 1,000mm, a mid rail, and a toe board of 100mm high if there’s a risk that objects can fall. Guardrails must be securely and continuously fixed and able to withstand the required loads.

📖 WHS Compliance Context

✦ KEY TAKEAWAYS

• ✓ Referenced in WHS Regulations and state/territory Codes of Practice.
• ✓ Cited as the primary Deemed-to-Satisfy Standard in the National Construction Code.
• ✓ Non-compliance can result in prohibition notices from WHS regulators.

AS 1657 2018 is heavily referenced in the Australian Workplace Health and Safety (WHS) Regulations and state and territory WHS/OHS Codes of Practice. It is also cited as the primary Deemed-to-Satisfy Standard in the National Construction Code (NCC). The Standard is widely recognised as the industry benchmark for platforms, walkways, stairways, and fixed ladders. Designers, manufacturers, and installers have a duty under WHS legislation to apply the Standard. Non-compliance can result in prohibition notices from WHS regulators.