Responsibility and Liability
The designer, manufacturer, contractor, roofing contractor, and the owner should be made aware of their responsibilities, and all parties are considered to have been informed of their obligation if they have sighted or signed a warranty.
If the requirements of the NZBC or consumer legislation knowingly cannot be met, or if the conditions of the warranty or the requirements are knowingly impractical or ignored, the liability remains with those who ignored them. There is an implied warranty requirement within the Building Act that the material selected and used will be suitable for purpose. The material can be used without compliance with the NZBC, but only on a written statement to that effect given by the roofing contractor and with the consent of the T.A.
Metallically Coated Cladding Endurance and Naturally Washed Cladding Endurance give an indication of the period that metal roof and wall cladding will not perforate from corrosion in a well-washed situation providing maintenance requirements are met. See Maintenance (NZBC: C. Maintenance)
In unwashed areas the durability of wall cladding, spouting or flashings are likely to be less than that indicated in the tables.
Metallically Coated Cladding Endurance and Naturally Washed Cladding Endurance do not necessarily consider the aesthetic appearance of the metal coating or the 'life to first maintenance '. See Repainting Painted Claddings.
The indication for rainwater goods depends on the environment and the ability of any spouting or gutter to be able to drain and avoid ponding.
The COP strongly recommends an enquiry into the terms and conditions of an expected warranty before finalising material selection and issuing tender documents, as Metallically Coated Cladding Endurance and Naturally Washed Cladding Endurance are not warranties.
The range in years provides for differences in each environmental category as described in Environmental Categories.
COP Category C — Moderate Marine
COP Category D —Severe Marine
COP Category E — Very Severe Marine
requirements of the NZBC.
R/W = Roof and walls
RGS = Rain-water Goods
Metallically Coated Cladding Endurance
INDICATIVE PERFORMANCE IN YEARS THAT NATURALLY WASHED METALLIC COATED STEEL BASED CLADDING WILL NOT PERFORATE FROM CORROSION.
Environmental Category | B/C | D | E | B/C | D | E |
Coating | R/W | R/W | R/W | RGS | RGS | RGS |
Galvanised Z450 AZ 150 Prepainted AZ150 Prepainted AZ200 | 15/30 15/40 30/40 30/50 | • • 15/25 20/40 | • • • 15 | • 10 10/15 12/15 | • • 10 10 | • • • • |
Naturally Washed Cladding Endurance
INDICATIVE PERFORMANCE IN YEARS THAT NATURALLY WASHED METAL CLADDING WILL NOT PERFORATE FROM CORROSION.
Environmental Category | B/C | D | E | B/C | D | E | B/C | D | E |
Coating | Roof | Roof | Roof | Wall | Wall | Wall | RGS | RGS | RGS |
Unpainted aluminium Polyester/Acrylic Aluminium PVF2 Aluminium Zinc Copper Stainless steel | 25/40 30/50 35/50 >50 >50 >50 | 20/30 25/50 30/50 >50 >50 >50 | 15/25 20/40 25/40 50 >50 >50 | 15/40 25/45 30/45 >50 >50 >50 | 15/30 20/40 25/40 >50 >50 >50 | 10/20 15/35 20/35 50 >50 >50 | 10 15 15 10 >50 >50 | 10 15 15 10 >50 >50 | 5 10 10 10 >50 >50 |
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