National Construction Code 2022: What You Need to Know

Introduction

As a structural designer in Australia, it is essential to have a deep understanding of the National Construction Code (NCC). The NCC is a set of minimum requirements for the design and construction of buildings in Australia.

The Australian Building Codes Board develops and maintains the NCC, and all states and territories of Australia adopt it.

The NCC is an important document that sets out the requirements for buildings in Australia. It covers a wide range of topics, including structural design, fire safety, plumbing, and energy efficiency. The NCC is updated every three years to reflect changes in technology, building materials, and building practices.

How often is the National Construction Code updated?

Australia's National Construction Code (NCC) is updated on a three-year cycle. This means that a new edition of the NCC is released every three years, with the most recent edition being the NCC 2022.

However, it is important to note that the NCC may also be amended outside of the three-year cycle if there are significant changes required due to safety or regulatory issues. These amendments are typically made in the form of "out-of-cycle amendments" and are designed to address any urgent issues that arise between editions.

It is important for those in the construction industry to stay up-to-date with the latest version of the NCC and any amendments, as compliance with the code is mandatory for all new building work in Australia.

Legal Implications of the National Construction Code

The NCC is legally binding, meaning that designers and builders must comply with its requirements. Failure to comply with the NCC can result in legal and financial consequences, including fines and legal action.

How is the National Construction Code used in the structural design workflow?

The National Construction Code (NCC) is an important document that sets out the minimum requirements for the design and construction of buildings and structures in Australia. As such, it plays a crucial role in the structural design workflow, particularly in ensuring that designs meet the relevant safety standards and regulations.

Here are some ways in which the NCC is typically used in the structural design workflow:

1. Determining the design criteria: The NCC provides guidance on the minimum structural requirements for buildings and structures, including loadings, material properties, and structural analysis methods. This information is used to determine the design criteria for a particular project, such as the required strength and stiffness of structural elements.
2. Developing the design: Once the design criteria have been established, the structural engineer will use this information to develop the structural design. This may involve selecting appropriate structural systems, determining member sizes and connections, and analyzing the structure to ensure that it meets the relevant safety requirements and performance standards set out in the NCC.
3. Checking compliance: Throughout the design process, the structural engineer must ensure that the design complies with the relevant sections of the NCC. This may involve checking that the structure meets the minimum strength, stiffness, and durability requirements, as well as ensuring that fire safety, accessibility, and other requirements are met.
4. Obtaining approvals: Before construction can commence, the structural design must be reviewed and approved by the relevant regulatory bodies. The NCC is used as a basis for this review, with the regulatory authorities checking that the design complies with the relevant sections of the code.

Overall, the NCC is an essential tool in the structural design workflow, helping to ensure that buildings and structures are designed and constructed to meet the highest safety and performance standards.

The National Construction Code 2022

Effective Date for National Construction Date 2022

The latest version of the NCC is the NCC 2022, which comes into effect on May 1, 2023.

The NCC 2022 includes a range of changes that will affect the way that structural designers approach their work. Note the changes regarding energy efficiency, condensation and liveable housing provisions won’t come into effect until 1st October 2023.

Major Changes in National Construction Code 2022

Energy Efficiency Requirements Changes

One of the major changes in the NCC 2022 is the introduction of new energy efficiency requirements. The new requirements aim to reduce greenhouse gas emissions and improve the energy efficiency of buildings while also trying to account for energy bills & societal costs of energy.

The 2019-2022 update introduced the new Section J, which includes revised requirements for insulation, glazing, and lighting in commercial buildings. In addition, the update requires improved performance for HVAC systems, including more efficient fans and motors, and requires consideration of solar panels and battery storage in new buildings.

Figure 1: Minimum thermal star rating increases from 6 → 7 (out of 10) and the new “Whole of Home” energy use rating ≥ 60 (out of 100) (Reference).

Livable Housing Design Changes

The NCC 2022 also includes new requirements for liveable housing design, which aim to improve the accessibility and adaptability of buildings. These requirements apply to all new Class 1a and 2 buildings and require a minimum level of accessibility and adaptability to meet the needs of people with disabilities and older Australians.

Changes to the accessibility requirements include:

• Step-free access through one external doorway
• Most internal doors into rooms must be ≥ 820mm clear width (Figure 2)
• Toilet on the ground floor
• Toilet & bathroom walls strong enough to attach grab bars (DTS requirements for plywood or nogging locations) (Figure 3)
• Additional voluntary standard for higher accessibility

Figure 2: Measurement of clear opening width required for accessibility requirement outlined in the NCC 2022 (Reference).

Figure 3: Locations for nogging for walls surrounding a bath in the NCC 2022 (Reference).

How does NCC 2022 affect structural engineers?

The NCC 2022 has significant impacts on the workflow of structural engineers working on residential and light commercial buildings in Australia. Here are some of the general changes and specific requirements for different building materials.

General Changes

One significant change in NCC 2022 is the introduction of new verification methods for structural design.

Engineers can now use either a deemed-to-satisfy approach or a performance-based approach under the housing provisions.

• The deemed-to-satisfy approach refers to the standard set of solutions that have been previously tested and approved, while
• The performance-based approach is a more flexible option that allows engineers to propose alternative solutions that can meet the performance requirements of the NCC.

There is also a new clause referencing system that is consistent across all volumes to improve usability.

Figure 4: New clause referencing system in the NCC 2022 (Reference).

Other general changes include:

• Revised definition of "Class 2 and 3 buildings" to include residential aged-care buildings
• Maximum number of storeys for timber-framed buildings increased to eight, subject to certain fire resistance requirements
• Use of cross-laminated timber (CLT) expanded to Class 2 and 3 buildings up to 25 metres in height

Footing & Slabs

The NCC 2022 introduces several changes regarding the footing and slab design requirements.

The new code now requires structural engineers to consider the effects of thermal bridging in their designs to achieve the energy efficiency requirements of the code. The new requirements also emphasize the importance of waterproofing and moisture protection to ensure the durability of the building's foundations.

Other changes include the minimum size and thickness of concrete footings being revised to better reflect soil types and loads and the clarification of design requirements for post-tensioned slabs. Housing provisions clause 4 is now restricted to soil classifications A, S, and M. In other conditions, design must be completed as per AS 2870 or AS 3600.

Masonry

The NCC 2022 introduces several changes in the design requirements for masonry.

One of the significant changes is the increased height limit for masonry walls that do not require a fire-resistant rating. Structural engineers now have to follow the new height limits to ensure compliance with the NCC.

There has also been a revision of design wind pressures on masonry buildings, with new requirements for masonry ties and connections as well as clarification of structural design requirements for masonry walls supporting roof loads.

Structural Steel

The NCC 2022 introduces significant changes in the design requirements for structural steel.

One of the major changes is the adoption of the latest version of the Australian Steel Design Standard AS 4100, which was revised in 2020. The new standard updates the design criteria for steel structures, including the design rules for slender sections, the use of buckling-restrained braces, and the design of connections.

Other changes include the revision of the minimum thickness of steel plates used in structural steel design to better reflect modern steel manufacturing processes as well as a revision of fire resistance requirements for structural steel columns, with new tables providing specific requirements based on the shape and size of the column.

ClearCalcs can be used to quickly design a steel beam to NCC 2022 using the Steel Beam Calculator to AS 4100:2020, as well as the latest AS 4100 standard, AS 4100:2020 Steel structures.

Warehouses

The NCC 2022 introduces specific requirements for warehouse structures, such as minimum clearances between storage racks and minimum aisle widths.

Structural engineers working on warehouse projects must ensure compliance with these requirements to avoid delays or rejections during the building approval process. There have also been revisions of requirements for structural design of industrial buildings, such as warehouses, to better reflect modern building practices and materials.

For example, warehouses (Clause 7b) include an additional 0.15 kPa load for solar panels on the philosophy that these are usually the only buildings that lack the capacity for solar panels in normal construction.

Revised Standards

The National Construction Code (NCC) is based on a set of standards that ensure minimum requirements for building and construction in Australia. The NCC provides guidance on the design, construction, and performance of buildings, structures, and their components. The standards used in the NCC are reviewed and updated regularly to keep up with changes in technology, materials, and construction practices.

In this section, we will discuss some of the key changes in the revised standards that will come into effect with the NCC 2022.

Steel Design: AS 4100: 1998 → 2020

AS 4100 is the Australian Standard for the design of steel structures. The revised standard AS 4100:2020 is the latest version of the steel design standard that will be used in NCC 2022.

The new standard will introduce some changes in design requirements for steel structures, including:

• More comprehensive coverage of composite beams and columns.
• Minor updates to bolt connection design with the new bolt grade 10.0 (as per AS 1252.1:2016), which has a special ductility factor in the shear strength formula as well as special friction considerations for slip-restricted bolts (Figure 5)
• Updated provisions for fire resistance design.
• New provisions for fatigue design.
• Revised load combinations for the ultimate limit state design.
• Corrected mechanical properties in elevated temperatures in Clause 12.4.3 which ensures the logical error where steel was becoming stiffer in higher temperatures has been rectified (Figure 6)

Figure 5: The bolt grade 10.0 introduced in both connection design in the Australian Standards for Steel Design AS 4100 (Reference).

Figure 6: Clause 12.4.3 in AS 4100 rectifitied the mechanical properties of steel in elevated temperatures (Reference)

For example, the new fatigue design provisions in AS 4100:2020 require the use of a fatigue category based on the type of loading and stress range. This category will affect the design of members and connections for fatigue resistance, leading to potential changes in the structural design.

ClearCalcs can be used to quickly design a steel beam to NCC 2022 using the Steel Beam Calculator to AS 4100:2020 as well as the latest AS 4100 standard, AS 4100:2020 Steel structures.

Wind Loads: AS/NZS 1170.2 : 2011 → 2021

Wind loads are a critical consideration in the design of structures, particularly in regions that are prone to severe weather events. AS/NZS 1170.2 provides the requirements for wind loads on structures in Australia.

The revised standard AS/NZS 1170.2:2021 is the latest version of the wind load standard that will be used in NCC 2022.

The new standard has seen significant updates to wind load maps (new regions A0, B1, B2 & NZ1-4) and revised wind pressure coefficients.

The special Fc and Fd factors for Regions C & D have been removed, and there is a new Climate Change Multiplier Mc = 1.0 or 1.05, which results in a 5% wind speed increase for the coastal north.

The updated wind pressure coefficients in AS/NZS 1170.2:2021 affect the design of cladding and roofing systems, particularly in high-wind regions.

Other changes include:

• All intermediate terrain categories except TC 2.5 (which is for outer suburbs) removed
• Shielding Multiplier Ms = 1.0 always if building h > 25 m
• Hill Multiplier Mh = 1.0 always if hill H < 10 m
• New open area / volume factor for open buildings
• Internal wind pressures now include Ka and Kl factors (Figure 7)

Figure 7: Internal wind pressues now include Ka and KI factors in the AS 1170.2:2021 (Reference).

Structural engineers and designers will need to adjust their designs to accommodate these changes in wind loads. ClearCalcs has a calculator for determining wind load (Wind Loads (AS/NZS 1170.2) Calculator to AS/NZS 1170.2:2021) which is automatically updated to factor in the latest changes when standards are revised to streamline the design process.

Residential Wind Loads: AS 4055 : 2012 → 2021

AS 4055 provides the requirements for wind loads on residential buildings in Australia. The revised standard AS 4055:2021 is the latest version of the wind load standard that will be used in NCC 2022 and has been explicitly derived from AS 1170.2:2021, so the changes are commensurate (wind regions and wind pressure coefficients). These revisions will result in changes to the design of roofing systems, particularly for low-pitch roofs.

Other changes include:

• Slightly different default KcCp,n factors
• Higher uplift on open areas such as verandahs
• Some factors are renamed; formerly notated as Cpt as per the below Table 3.2.1 which denotes the Pressure Coefficients for Roof and Wall Wind Classifications (Figure 8).

Figure 8: Table 3.2.1 in AS 4055:2021 illustrates the renaming of pressure coefficients for roof and wall wind classifications formerly notated as Cpt (Reference).

ClearCalcs has both the latest standard available for residential wind loads (AS 4055-2012 Wind loads for housing) as well as a calculator for Wind Bracing Analysis (AS 1684.2:2021 & AS 4055:2021) which combines both standards into a single analysis and is automatically updated to design to the latest changes when standards are revised to streamline the design process.

Overall, the updated standards in NCC 2022 will have significant implications for structural engineers and designers in Australia (you can also watch the recorded webinar on NCC 2022). It is essential to stay up-to-date with these changes to ensure compliance with the latest standards and ensure the safety and performance of buildings and structures. Using ClearCalcs can ensure that your designs are automatically updated to reflect these changes to ensure compliance.

Conclusion

In conclusion, the National Construction Code plays a vital role in ensuring the safety and compliance of buildings in Australia. As a structural designer, it is crucial to have a deep understanding of the NCC's requirements and how they affect the design workflow.

ClearCalcs is an online structural design platform that can help structural engineers, architects, and building designers ensure compliance with NCC 2022. ClearCalcs provides access to the design tools to help designers streamline their workflow and save time on structural design while also complying to the latest standards.

By using ClearCalcs, designers can ensure that their designs comply with NCC 2022 and other relevant Australian Standards. With ClearCalcs, designers can focus on their core tasks of designing structures, knowing that their designs comply with the latest building and construction codes in Australia.

Note; NCC 2019 will still be usable and maintained in ClearCalcs for existing and new projects, though no new features will be added.