Driving Practical Outcomes for Steel Framing in NCC 2025

Key outcomes shaped through advocacy and industry collaboration

BlueScope has worked alongside the National Association of Steel-Framed Housing (NASH) and regulatory bodies to help shape practical, evidence-based outcomes in the National Construction Code (NCC) 2025 – supporting a more efficient and competitive future for the steel framing industry.

Through sustained advocacy, technical research, testing and collaboration, two key outcomes have been achieved for the light gauge steel (LGS) framing industry – creating a simpler, more efficient compliance pathway that reduces complexity for builders.

Advocating for thermal break outcomes

In the lead-up to NCC 2025, proposed changes to the energy efficiency provisions would have required significant changes to the application of thermal breaks in steel framed roofs and walls.

This would have introduced additional cost and complexity for builders, and the building science demonstrated that there would be no performance benefit from the proposed changes.

NASH and BlueScope worked closely to develop and submit a large body of evidence. BlueScope’s research collaboration with the Sustainable Building Research Centre on the thermal performance of lightweight steel construction provided strong evidence that the proposed requirement was not necessary.

Outcome:

Following extensive engagement with building policy stakeholders, the proposed change was not adopted in the NCC.

Consequently, there are no additional thermal break requirements for battened-out steel framing under NCC 2025, thereby avoiding unnecessary costs and preserving established construction practices.

Securing Deemed-to-Satisfy recognition for fire-protected steel

A second major focus area was the recognition of fire-protected steel* construction within the NCC.

In previous editions, fire-protected steel was not recognised as a Deemed-to-Satisfy (DtS) solution, unlike concrete, masonry and fire-protected timber. This created an additional compliance burden and often required project-specific fire engineering for commercial and mid-rise buildings.

A significant fire and structural research and testing program supported a Proposal for Change (PFC) for the inclusion of fire-protected steel in the NCC. BlueScope, together with NASH, undertook a sustained advocacy program, engaging with regulators and obtaining support from broader construction industry stakeholders.

Outcome:

NCC 2025 now recognises fire-protected steel, as a DtS construction method for load bearing internal walls in Class 2 to 9 buildings.

This represents a significant regulatory milestone for the industry, reducing compliance uncertainty and making it easier to specify and build with steel framing in commercial and mid-rise applications.

Other NCC 2025 updates relevant to steel framed housing

NCC 2025 also introduces amendments to condensation management provisions for housing, including:

• Minimum permeance requirements of control layers in wall construction (such as wall wraps and pliable membranes) now applied nationally across all climate zones
  • The requirement for class 4 permeability that was introduced for cold Climate Zones 6, 7 and 8 in NCC 2022 will not change
  • Lower permeance classes have been introduced in other climate zones that have lower condensation risk
• The introduction of a mandatory drained and vented wall cavity for houses in cool and cold climates when fixing lightweight cladding to both timber and steel framing
  • A minimum 12mm deep cavity is required in Climate Zones 6, 7 and 8
     

Design and construction considerations for steel framing systems

While the NCC 2025 condensation management provisions do not specifically change requirements for framing made from TRUECORE® steel, they may influence how wall systems are designed and specified.

• Greater awareness is needed to ensure all performance requirements, including energy efficiency, condensation management and constructability, are appropriately balanced to achieve compliant outcomes
• The introduction of a drained and vented cavity requirement aligns steel framing with mainstream construction practices:
  • A minimum 12mm cavity in Climate Zones 6, 7 and 8 can be readily achieved using established methods, such as battened-out cavities and thermal breaks
  • This supports straightforward compliance using familiar construction approaches

What this means for TRUECORE® steel customers

These outcomes reflect the value of BlueScope’s industry advocacy and technical leadership, helping to deliver practical and efficient pathways for working with steel framing.

• Greater certainty with a clear DtS pathway for fire-protected steel
• Simplified compliance for commercial and mid-rise projects, with reduced reliance on bespoke fire engineering
• Reduced design complexity and rework, supporting more efficient detailing and fabrication
• Continued use of established steel wall systems, without additional thermal break requirements

More broadly, these changes strengthen the competitiveness of steel framing and support its role in modern construction methods.
 

Supporting industry guidance and ongoing collaboration

To support practitioners in navigating the NCC 2025 requirements, additional industry guidance is now available, with further resources under development by NASH. and continues to be developed.

NASH has published a series of Technical Notes addressing thermal bridging and condensation, while the TRUECORE® steel website includes resources that clarify common misconceptions around steel-framed homes, particularly in relation to energy efficiency and moisture management.

Together, these resources aim to support more informed decision-making and balanced design and construction outcomes, helping practitioners deliver compliant, high-performing and durable building solutions with frames made from TRUECORE® steel.

Further information

• Download: NASH Technical Notes, Building Envelope Series including:
  • No. 8.1 – Building Envelope – Thermal Bridging
  • No. 8.2 – Building Envelope – Thermal Breaks
  • No. 8.3 – Building Envelope – Thermal Bridging verses Thermal Breaks
  • No. 8.4 – Building Envelope – Battening Out Lightweight Cladding
  • No. 8.5 – Building Envelope – Ventilation of Air Spaces
  • No. 8.6 – Building Envelope – Steel Framing and Total R-Values
     
• Download: NASH Technical Note: No. 9 – NCC 2025 Drained and Ventilated Cavities
   
• Visit: TRUECORE® steel resources addressing steel framing misconceptions
  • Thermal efficiency of steel frames
  • Condensation and steel framed homes