NCC 2022: what's new for residential structural design

When NCC 2022 takes effect and what was delayed

Brooks confirmed that NCC 2022 took legal effect on May 1, 2023 across all Australian states and territories. Three provisions did not commence on that date: energy efficiency, condensation management, and livable housing were each given a delayed commencement of October 1, 2023. Brooks attributed the delays to COVID-related implementation difficulties and to controversy around the energy efficiency requirements, which had attracted pushback before the code was finalised.

Engineers designing to NCC 2022 from May 2023 were working under the full code except for those three delayed sections.

Energy efficiency, condensation, and livable housing changes

The energy efficiency changes are the most visible update in NCC 2022. The minimum NatHERS star rating for Class 1 buildings increased from 6 to 7, and a whole-of-home energy use budget was introduced: a minimum score of 60 for detached houses and 50 for apartments. These targets are primarily for architects and energy assessors to meet, but thicker wall assemblies from higher insulation requirements can affect structural details at openings and eave connections.

Condensation management is now a code requirement with waterproof membrane provisions. The livable housing provisions set a minimum 820mm clear door width and require grab bar-ready construction in bathroom and toilet walls - structural backing behind wall linings must be specified to carry future loads from those fittings.

Structural standards updated under NCC 2022

Brooks covered the major changes to referenced structural standards. In AS 4100 (steel): Grade 10.9 bolts were added, fire design calculations were updated, and errors in the elevated temperature mechanical properties were corrected. These corrections affect fire-engineering calculations for steel members.

AS/NZS 1170.2 (wind loads) received a comprehensive rewrite. Wind regions were redefined and a new Region A0 was added. Terrain category guidance was clarified. New open area and volume factors were introduced, and internal pressure coefficients now include K and KL factors for buildings with large openings. A 5% wind speed multiplier was added for coastal northern Australia to account for climate change projections. Brooks described this as one of the more impactful changes for residential practitioners who routinely use wind load inputs.

New Class 7B warehouse solar load

NCC 2022 introduced a 0.15 kPa additional roof load for Class 7B warehouse buildings to accommodate future solar panel installation. Brooks explained this was an industry compromise. The load accounts for the dead weight of panels but deliberately excludes wind loading on inclined panels - the future panel orientation is not known at design time.

John Birch asked during Q&A whether the 0.15 kPa applied alongside the standard 0.25 kPa superimposed load; Brooks confirmed it is additional. A follow-up question asked whether the 0.15 kPa considered wind on inclined panels; Brooks suggested industry pressure prevented inclusion of complex wind calculations for a future configuration unknown at the time of building design.

Soil classification and footing design changes

The prescriptive footing and slab design pathway has been restricted. Under NCC 2022, that pathway is limited to Class A (slightly reactive) and Class S soils. Sites with highly or extremely reactive clay must be designed to AS 2870 or AS 3600 and cannot use the deemed-to-satisfy prescriptive provisions. The masonry clause was also significantly reorganised, though the performance requirements themselves remain unchanged.

How Calcs.com handles the transition

Brooks confirmed that all new default calculators in Calcs.com are NCC 2022 compliant. Legacy NCC 2019 calculators remain available under the old revisions category and will continue to function but will not receive new feature additions. The platform displays integrated standard references in sidebars so the edition of each cited standard is visible in the calculation output, supporting the engineer's obligation to verify that the referenced editions match the adopted code for their jurisdiction.