COP v3.0:introduction

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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 the fixing of metal roof and 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 3).

The most recent Update to the COP was on 1 May 2019.

Important updates:

The main clause Roof Ventilation was renamed 10 Internal Moisture and completely revised and updated. The revised clause recommends designing and installing roof cladding to allow natural ventilation in residential buildings and requires design to enable ventilation in skillion, sarked, and low-pitched residential roofs.

Summary of other changes in this update

  • The main clause 14 Installation was revised and updated for clarity.
  • Some clauses from 13 Site Practice were moved to be included in the more relevant clause Installation. Site Practice now contains mainly 13.1 Safety.
  • Some clauses in 17 Testing were renamed and renumbered to fix broken links and reflect content more accurately. A major revision of 17 Testing is underway. 
  • Other changes are Category 1 updates, which fixed minor errata such as grammar, spelling, and layout.

See 19.1 2019 – May for details of the changes in this Update.