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We’ve got coastal construction covered, with Z450 to be exact.


The new Rondo Z450 Top Hats are an ideal solution for construction projects in high corrosion zones, particularly in coastal areas.

High Corrosion Zones and Compliance

In Australia and New Zealand, the corrosivity level of an environment can be categorised into six types, from “very high” to “very low” corrosivity. These categories are indicated as: C1, C2, C3, C4, C5 and CX.

The level of corrosivity depends on the presence, and saturation of environmental elements such as acids, and moisture with oxygen, which affects the iron in steel products, causing oxidisation and rust to occur at an accelerated rate.

This can lead to premature building maintenance requirements, function failures, and health and safety risks to building occupants.

To reduce the risk associated with corrosion, the NCC has outlined performance requirements in for building materials used these zones, that are deemed fit for purpose, and compliant. These performance requirements include a substantial coating of protective zinc on steel members and are outlined in AS4312:2019.

Rondo Z450's Higher Corrosion Protection 

With a generous zinc coating mass of 450 (g/m²), Rondo Z450 are the only Top Hats on the market for external walls and facades with a rain screen façade or ventilated in C3 and C4 corrosion zones.

A 63% increase in zinc coating than our standard Z275 Top Hats acts as a longer lasting sacrificial barrier, protecting the steel against corrosivity, and extending the life to first maintenance of the Z450 Top Hats.  

Ideal for Coastal Construction

Not only ideal, these Z450 Top Hats were designed for coastal construction projects.  

Coastal areas, which occur mainly within 1 kilometre of an ocean or bay, are categorised as C3 and C4 zones. The environment of these zones presents a unique set of challenges for architects, builders, and contractors, who must contend with several elements like humidity and saltwater exposure, ensuring that building materials specified and installed are suitable to withstand corrosion.

Z450 Top Hats are suitable for buildings where the external walls have a rain screen façade or external walls and soffits that are ventilated, and when C3 or C4 corrosion zones have been specified.

Use our quick reference guide below to easily determine whether your project requires Z450 Top Hats.


For more information on our Z450 Top Hat options, click here.

To obtain a complimentary, compliant design for a project in a coastal or other high corrosion zone, submit a technical inquiry to our qualified Design Engineers.