A ridge flashing has traditionally been thought of primarily as a weatherproofing component. It covers the point where two roof slopes meet, helps keep wind-driven rain out and gives the roof a clean, finished edge.
Under NCC 2025, however, there is another consideration on applicable residential roof designs: moisture management.
Victoria adopted NCC 2025 from 1 May 2026. Among the changes are stronger condensation-management provisions for walls and roofs. Victorian BPC guidance explains that the roof requirements now distinguish between different roof-space configurations, including whether the primary insulation layer is parallel to the roof plane.
For metal roofing, the Australian Steel Institute has published specific interpretation guidance to help designers, builders and certifiers apply the new provisions. Its guidance considers ventilation openings, membranes, insulation and how common steel roof configurations can satisfy the intent of the NCC.
This does not mean every ridge suddenly needs to become a ventilated ridge. It does mean that where a roof design relies on high-level ventilation at or near the ridge, the ridge detail needs to be considered as part of the ventilation strategy rather than as an isolated cap added at the end.
The ridge now has several jobs to do
A well-designed ridge still needs to shed water effectively, provide suitable coverage over the roof sheets and accommodate the geometry of the roof. On some projects, it may also need to work around an intentional high-level airflow path.
That creates a balancing act. Closing every possible gap may appear to improve weatherproofing, but it can undermine a ventilation path that has been designed to manage moisture. Leaving openings without the right detailing, on the other hand, can increase exposure to wind-driven rain, pests or embers.
The Australian Steel Institute notes that compatible mesh can be used over some ventilation openings where it still facilitates the drainage and ventilation required by the NCC. Its 2026 guidance specifically discusses non-combustible, corrosion-resistant mesh as a way of combining functions such as ember or vermin resistance with roof ventilation.
For roofers and designers, this makes the detail around a ridge flashing or ridge roof cap more important. Roof pitch, sheet profile, cover, ventilation opening, mesh selection, fixing method and adjacent membranes all need to work together.
Custom fabrication can help resolve unusual roof geometry
Standard ridge capping remains suitable for many straightforward roofs. But commercial, industrial and architecturally detailed projects often introduce non-standard pitches, wide ridge conditions, unusual roof-sheet profiles or other constraints.
This is where custom fabrication becomes useful. Rather than adapting the roof to suit a generic profile, the capping can be folded to the project dimensions and coordinated with the surrounding roof assembly.
The key point is that custom capping does not replace correct design. It gives designers and roof plumbers the ability to fabricate the profile that the approved detail actually requires.
Think about the whole roof assembly
One of the useful lessons from the NCC 2025 changes is that condensation cannot be solved by one component alone. The performance of a metal roof depends on how insulation, membranes, eave ventilation, ridge ventilation, flashings, penetrations and internal moisture loads interact.
A ridge detail that works perfectly on one roof may not be appropriate on another.
For projects in Victoria, it is therefore worth resolving the ventilation and flashing strategy early, before fabrication and installation begin. That can reduce improvisation on site and help ensure the finished ridge performs the way the roof designer intended.
PPC Flashings manufactures standard and custom ridge capping and other folded metal flashings to suit project-specific dimensions and roofing requirements. Where a roof requires a non-standard ridge profile, our team can work from the supplied specifications to fabricate the detail required.
Project-specific requirements should always be confirmed against the current NCC, relevant Australian Standards and approved project documentation.
The information contained in this news post is provided by way of general information only and has not been prepared with your specific needs in mind. Before application in a particular situation, we recommend that you obtain expert advice confirming the suitability of the services and/or products and information in question for the application proposed.