Weathering Steel (Corten®)


Weathering steel comes under some other more common terms such as Xlerplate® and Corten®.

The principle of the material is that via the natural weathering process the surface rusts and creates a protective layer. This layer, providing the environmental conditions are not extreme, can protect the steel from rusting further whilst producing a deep brown patina that varies slightly with time without any further surface treatment. Scratching or marking can be lightly sanded to remove the worse effect and then left to naturally patina.

In almost all cases where the the weathering steel is specificed as a façade cladding on building projects, it will be used as a rainscreen element, installed on a Thermosash engineered rail system over a weathering line on a cavity wall system consisting of a Rigid Air Barrier (RAB).

Things to note about weathering steel:

  • Long lasting building element with low maintenance requirements.
  • Imposed weight on building structure to be considered.
  • It is not generally designed as a weathertight system and requires a RAB behind.
  • Weathering steel requires some ageing process to prevent staining of surrounding building materials.

NB: Corten is a raw material sourced from steel merchants. Thermosash adds value to the product by turning it into a warrantable building'system'.

Download uncoated steel datasheet: AS/NZS 1594-HA350

NB: Thermosash are specific design commercial façade engineers and contractors and are unable to assist with residential and landscape weathering steel enquires.

Relevant Projects

North Shore District Court

North Shore District Court


Architects New Zealand

Fletcher Construction


Iron Bank

Iron Bank


RTA & Partners

Macrennie Construction