Material Selection

The selection of the most suitable material for metal roof and wall cladding, compliant with the durability requirements of the NZBC, depends on the design of the building and its location or environmental category.

Manufacturers offer different metallic and paint coatings and different metals that are suitable for all different environments.

Designers are urged to select the material in conjunction with the conditions of any expected warranty before the material is specified. The durability of the material is not necessarily confined to the number of years stated in a warranty and is only indicative of the performance of different substrates and coatings.

Those factors that the designer can influence are covered in many other sections of this Code. Cost and colour should not be the major determining factors, and designs using unwashed areas or detailing using different metals requires careful material selection.

Any warranty for roof or wall cladding is divided into two parts, the material, and the workmanship. Workmanship warranties are usually provided by the Roofing Contractor for a minimum period of two years; however, this period is extended to five years by Roofing Contractors who are members of RANZ.

There is a difference between the warranty offered for residential and commercial use of metal roof and wall cladding.

The maintenance of metal roof and wall cladding is very dependent on two factors - design and materials.

The preparation of a maintenance manual for owners is an indication to the owner that periodic maintenance is required to comply with the manufacturer's warranty conditions.