FTI-Group-logo
1300 751 701

Welcome to the
FTI Group blog

Here you’ll find a range of articles that detail topical industry information and product news

Exploring More Compliance Hurdles in Stair and Handrail Design

In our previous blog, we delved into the top four compliance issues our Design Team encounters while assessing fire cores. In this installment, we’re going deeper into common compliance concerns, highlighting four additional issues that pertain to fire cores, stairs, and handrails.

5. Riser Height.

The BCA/NCC Code sets a maximum of 190mm and a minimum of 115mm for riser height, which falls short of good industry standards. Although there is an allowance between adjacent risers and overall, there’s no tolerance written into the code for anything over the 190mm maximum or under the 115mm minimum, meaning anything beyond these limits is considered non-compliant.

See below excerpt of the NCC 2022 Table D3D14.

What we commonly see onsite is, the stair flights being installed or formed either too high at the top, or too low at the bottom because of the landings being set at the incorrect height. This error tilts the stair up causing the risers heights to measure over the 190mm maximum or under the 115mm minimum, which is then deemed non-compliant.

To ensure compliance and avoid costly repercussions, it’s advisable to design stairs with riser heights comfortably within the specified limits. Even a slight deviation of 2mm can make all the difference for compliance tolerance. This approach mitigates the need for extensive discussions, performance solutions, and potential redesigns, ultimately saving time and money, particularly when considering the expensive process of refacing risers to meet minimum requirements.

6. Clear Width.

According to the NCC 2022, Section D2D8 Clause 1 (a), the minimum required width of exits, and paths of travel to exits is 1000mm from the inside of the handrail to any obstruction, i.e. a wall, hydrant, services etc.

See below excerpt from the NCC 2022, Section D2D8 Clause 1 (a).

On some projects, we see stair widths designed at the minimum of 1000mm, which does not align with industry best practices. The problem arises when adjacent walls bulge or deviate, encroaching upon the 1000mm clearance and rendering it below the required minimum, thus becoming non-compliant.

To ensure compliance and avoid complications, it’s advisable to design stairs with a clear width of at least 1050mm. Even adding an extra 25mm can significantly improve compliance tolerance. This proactive approach helps to circumvent costly and time-consuming discussions, performance solutions, potential redesigns of the stairs, and the substantial onsite expenses required to rectify the issue.

7. Door Swing.

In line with the NCC 2022 Section D3D25 Clause 1(a)(i), the swing of a door must not be encroached upon by greater than 500mm.

See below excerpt of the NCC 2022 Table D3D14.

 

Sometimes we see stairs designed with handrails encroaching upon the 500mm clearance, which doesn’t meet industry standards. This presents an issue because when the clearance is less than 500mm, the swing of doors is likely to hinder or obstruct the path of those already using the stairway.

To ensure compliance and prevent complications, it’s recommended to design stairs with a minimum clearance of 550mm, or even increasing it to 525mm will make a big difference for compliance tolerance. This will help avoid costly and time-consuming discussions, performance solutions, potential redesigns of the stairs, and the expensive onsite costs required to rectify the issue.

8. 2 x Risers + Going.

‘2 x risers + going’ refers to the combined vertical and horizontal dimensions of a stair step. The risers are the vertical portions that connect each tread, while the going refers to the horizontal surface of each step. When you add the height of the risers to the depth of the going, you get the total distance covered by one step in a staircase. This measurement is crucial in stair design to ensure that each step is comfortable and safe for users to ascend or descend.

The formula ‘2 risers + going (2R+G)’ is a common method used in stair design and building regulations to assess the relationship between the height of the risers and the depth of the treads, known as the going. The reason for adding two risers to the going is to provide a comprehensive measurement that accounts for the vertical ascent or descent (risers) as well as the horizontal distance covered by each step (going). By considering two risers instead of just one, it ensures that the measurement includes both the rise and run of the stairs, providing a more accurate representation of the step’s overall size and usability. This formula helps ensure that stairs are designed with appropriate proportions for safe and comfortable use.

As per the NCC 2022, Table D3D14, the acceptable range for the minimum 2R+G is 550mm, while the maximum allowable measurement is 700mm.

See below excerpt of the NCC 2022 Table D3D14.

An example of this issue arises when the tread depth measures 250mm, yet the riser heights fall short, such as at 148mm, resulting in a 2R+G calculation of 546mm (2 x 148mm + 250 = 546mm). Similarly, when the tread depth extends to 325mm and riser heights reach 190mm, the 2R+G exceeds the permissible range, calculating to 705mm (2 x 190mm + 325mm). In both scenarios, the measurements violate the specified range of 550mm to 700mm, rendering them non-compliant.

To avoid such issues, it’s essential to design stairs with a 5-10mm tolerance to accommodate any unforeseen variations in as-built or site conditions. This proactive approach helps prevent costly and time-consuming discussions, performance solutions, potential redesigns of the stairs, and the significant expenses associated with onsite rectification.

Tools to help you.

We recognise that the Building Code of Australia (BCA) and the National Construction Code (NCC) can sometimes be unclear and confusing due to the complexity, vague language, evolving standards, performance-based approaches, and varying interpretations of the codes.

To assist you in understanding and applying the codes to stairs and railings, we have invested in design tools specifically designed for this purpose. These tools will help you interpret and navigate the codes easier, ensuring compliance and clarity in your stair and railing designs.

Fast Tread® Handrail & Stair Guidelines.

We have developed a set of fundamental compliance guidelines to assist our clients in identifying potential compliance issues before manufacturing and construction begin. These guidelines are outlined based on our understanding and interpretation of the BCA/NCC and Australian Standards.

Download your copy here.

Fast Tread® BIM Content.

We understand the challenges of modelling and documenting in Autodesk Revit, so we have invested in developing a comprehensive suite of highly parametric Revit Content specifically for Fast Tread® stairs and handrails.

Our Revit Content is designed to streamline the modelling and documentation process, significantly reducing the time and effort required. But it doesn’t stop there. Our Fast Tread® Revit Content goes beyond mere convenience. It incorporates embedded design guidelines that help interpret and apply Australian Standards and the NCC to railings and stairs.

Download your copy here.

Compliance Mark-up by the FTI Design Team.

The Compliance Mark-up involves a full compliance review of the Architectural drawings to identify and flag any actual or potential compliances issues with regards to the stairs and handrail based on our interpretation of the BCA/NCC & Australian Standards and as outlined in the Fast Tread® Handrail & Stair Compliance Guidelines.

For more information on the compliance of FTI products call the FTI Design Team on 1300 751 701 or email design@ftigroup.com.au.

Share Post:

Stay Connected

More Updates

Maximising Metal Decking Formwork: Key Design Considerations for Enhanced Safety and Performance

Metal decking formwork is widely used in modern construction for its versatility from civil applications and sacrificial formwork to concrete slabs with full composite action.

Whilst it’s crucial for a product to be certified and compliant with relevant building codes, it’s equally important to have a comprehensive understanding of composite action to realise the full potential of metal decking formwork.

Exploring the Versatility of Metal Decking Formwork

Metal decking formwork offers unmatched versatility in modern construction. From supporting deep beam style slabs to simplifying box culverts and composite slabs, its flexibility shines through a diverse range of projects.

Whether you’re building high-rise structures or managing stormwater runoff, metal decking formwork is the versatile solution for ensuring structural integrity and efficiency in your projects.

Follow us on Linkedin to stay up to date

You can trust Fast Tread®
to be compliant with:

• AS/NZS1657:2018
for fixed platforms, walkways, stairways, and ladders
• AS/NZS1428.1:2009
for design for access and mobility
• AS/NZS1170.1:2002
for structural design actions
• AS/NZS3990:1993
for mechanical equipment
• AS/NZS4100:1998
for steel structures
• AS/NZS4991:2004
for lifting devices
• AS/NZS1554.1:2011
for structural steel welding
• AS/NZS4761:2001
for steel reinforcing materials

Compliance assured for your peace of mind. For more information, contact our design team.