The NZ Metal Roof and Wall Cladding Code of Practice (COP) is published by NZ Metal Roofing Manufacturers Inc. (MRM), to provide:

  • acceptable trade practice for fixing metal roofing, metal wall cladding, and accessories,
  • prescriptive detailing for designers, and
  • sets a benchmark for the standard of detailing and workmanship required over and above that required to comply with the NZBC.

The COP does not describe or dismiss alternative methods, which may need specific acceptance by the Building Consent Authorities.

It is published in accordance with current technology, materials, and building codes. The COP will be periodically updated to reflect changes in legislation and standards or improvements in technology and available materials.

The most current Code of Practice is available on the MRM website,, as Code of Practice Online (MRM COP Version 24.06).

The latest update to the NZMRM Code of Practice, v24.06 was published on 1 June 2024.

The updates published on 1 June 2024 include improvements to Gutter Support Systems and clarifying recommendations to prevent negative pressure with Ridge Vents. Substantial changes include removing wind load/span graphs for 0.70 mm aluminium.

Editing and rearrangement updates involve updating and editing images for consistency, clarifying Roof Cladding Expansion Provisions, material thickness, and amending references to the availability of AM Coatings in New Zealand. Minor edits were made for grammar, style, clarity, and consistency.

Notable revisions:

  • We removed the option of 0.70 mm Aluminium cladding from Aluminium Cladding Wind Load Span Graphs because 0.90 mm Aluminium is offered as a standard thickness.
  • Experience showed that hot-dipped galvanised gutter support brackets are not as durable as pre-painted steel products. Therefore, we added some recommendations to improve the durability of Gutter Support Systems.
  • Although not a change in recommendation, we added a statement to Ridge Vents to help prevent negative pressure in roof cavities.
  • We clarified the positioning of oversized holes and washers to aid in making Roof Cladding Expansion Provisions.

In addition to these and some minor edits and rearrangements, several images have been revised for consistency. For a detailed list of revisions, please visit v24.06 – June 2024.

Clause Number: 
Revision Category: 
2 - Editing and rearrangement
Revision Detail: 

Rewriting for clarity. No changes in recommendations.

Draft Clause: