New Zealand Metal Roofing Manufacturers (NZMRM)

The New Zealand Metal Roofing Manufacturers association (NZMRM) is an industry body representing companies that roll-form and supply metal roofing and wall cladding in New Zealand. Its website is metalroofing.org.nz.

Code of Practice

NZMRM's best-known work is the NZ Metal Roof and Wall Cladding Code of Practice, a comprehensive design and installation guide for metal roofs and walls. It is recognised as a related document for Acceptable Solution E2/AS1 of the New Zealand Building Code, which covers external moisture (weathertightness). The code is updated regularly; the version listed on the association's website in 2026 was v26.09. It is published online so designers, roofers and building consent authorities can use the current version.

The Code of Practice covers topics such as:

• choice of material and coating for different exposure environments, from sheltered inland sites to severe marine and geothermal areas;
• minimum roof pitches for different profiles;
• fastener types, spacing and placement for wind loads;
• flashing design, including ridge, barge, apron and penetration flashings;
• allowance for thermal expansion of long sheets;
• compatibility between metals and with other materials, to avoid corrosion;
• maintenance, including washing of areas not rain-washed.

Context

Profiled metal roofing, mainly corrugated and trapezoidal coated steel, is the most common roof type in New Zealand, and metal tiles are also widely used. Strong winds, high rainfall and salt-laden air near the coast make correct design and installation important for service life.

Related bodies

The Roofing Association of New Zealand (RANZ) represents roofing contractors, while BRANZ carries out independent building research. Roofing work on homes is also subject to New Zealand's Licensed Building Practitioner scheme. In Australia, roofing practice for metal is guided by standards such as AS 1562.1 and by manufacturers' and industry guides.