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Although the information contained in this Code has been obtained from sources believed to be reliable, New Zealand Metal Roofing Manufacturers Inc. makes no warranties or representations of any kind (express or implied) regarding the accuracy, adequacy, currency or completeness of the information, or that it is suitable for the intended use.

Compliance with this Code does not guarantee immunity from breach of any statutory requirements, the New Zealand Building Code or relevant Standards. The final responsibility for the correct design and specification rests with the designer and for its satisfactory execution with the contractor.

While most data have been compiled from case histories, trade experience and testing, small changes in the environment can produce marked differences in performance. The decision to use a particular material, and in what manner, is made at your own risk. The use of a particular material and method may, therefore, need to be modified to its intended end use and environment.

New Zealand Metal Roofing Manufacturers Inc., its directors, officers or employees shall not be responsible for any direct, indirect or special loss or damage arising from, as a consequence of, use of or reliance upon any information contained in this Code.

New Zealand Metal Roofing Manufacturers Inc. expressly disclaims any liability which is based on or arises out of the information or any errors, omissions or misstatements.

If reprinted, reproduced or used in any form, the New Zealand Metal Roofing Manufacturers Inc. (NZMRM) should be acknowledged as the source of information.

You should always refer to the current online Code of Practicefor the most recent updates on information contained in this Code.


This Code of Practice provides requirements, information and guidelines, to the Building Consent Authorities, the Building Certifier, Specifier, Designer, Licensed Building Practitioner, Trade Trainee, Installer and the end user on the design, installation, performance, and transportation of all metal roof and wall cladding used in New Zealand.

The calculations and the details contained in this Code of Practice provide a means of complying with the performance provisions of the NZBC and the requirements of the Health and Safety at Work Act 2015.

The scope of this document includes all buildings covered by NZS 3604, AS/NZS 1170 and those designed and built under specific engineering design.

It has been written and compiled from proven performance and cites a standard of acceptable practice agreed between manufacturers and roofing contractors.

The drawings and requirements contained in this Code illustrate acceptable trade practice, but recommended or better trade practice is also quoted as being a preferred alternative.

Because the environment and wind categories vary throughout New Zealand, acceptable trade practice must be altered accordingly; in severe environments and high wind design load categories, the requirements of the NZBC will only be met by using specific detailing as described in this Code.

The purpose of this Code of Practice is to present both Acceptable Trade Practice and Recommended Trade Practice, in a user-friendly format to ensure that the roof and wall cladding, flashings, drainage accessories, and fastenings will:

  • comply with the requirements of B1, B2, E1 E2 and E3 of the NZBC;
  • comply with the design loading requirements of AS/NZS 1170 and NZS 3604 and with AS/NZS 1562;
  • have and optimised lifespan; and
  • be weathertight.

COP v24.06:Useful-Information; Conversion-Factors

18.1 Conversion Factors 



18.1A Measurement Conversions

To convert from thisinto this
To convert this back
multiply by this
divide by this
cubic footcubic metre0.028317
cubic inchcubic millimetre16387.1
cubic yardcubic metre0.764555
foot per minutemetre per minute0.3048
foot per minutemetre per second0.00508
foot per secondmetre per second0.3048
foot pound force per secondwatt1.35582
gallon (Imp)litre4.54609
gallon (US)litre3.78541
inch mercurykilopascal3.38638
inch water gaugekilopascal0.248642
kilometre per hourknot0.539
knotkilometre per hour1.852
knotnautical mile/h1
knotmetre per second0.515
metre Head of waterkPa9.8
mile per hourkilometre per hour1.609344
millimetre mercurykilopascal0.133322
millimetre water gaugepascal9.78904
ounce per square footgram per square metre305.152
ounce per square yardgram per square metre33.9057
pound forcenewton4.44822
pound force footnewton.metre1.35582
pound force inchnewton.metre0.112985
pound force per square footkilopascal0.0479
pound force per square inchbar0.69
pound force per square inchpascal6894.76
pound force per square inchkilopascal6.89476
pound force per square inchmegapascal0.006895
pound per cubic footkilogram per cubic metre16.0185
pound per footkilogram per metre1.48816
pound per square footkilogram per square metre4.882
square footsquare metre0.092903
square foot per tonsquare metre per tonne0.091436
square inchsquare millimetre645.16
square milesquare kilometre2.59
square yardsquare metre0.836127
Steel thickness in mmWeight of steel kgs/m²7.85
ton force footkilonewton metre3.03703
ton force per square inchmegapascal15.4443
ton per cubic yardtonne per cubic metre1.32894
ton, freight (40 ft³)cubic metre1.13267


Water 0 ̊ – 100 ̊ increases in volume by 4.4%
1 litre    = 1 kg = 0.001 m3
1 m3      = 1000 litres
Weight of steel kgs/m2     = thickness in mm x 7.85
1 kN     = 102 kg
1 kip     = 6.895 MPa