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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; Material-Density-Melting-Point-Expansion-And-Modulus

18.3 Material Density, Melting Point, Expansion And Modulus 


18.3A Density, Melting Point, Expansion and Young Modulus

Melting point
Youngs modulus
Air acetylene 2500*  
Aluminium, rolled27106582469
Carbon Dioxide 0°C1.99   
Concrete, reinforced 2% steel2420   
Hydrogen 0°C0.0897   
Helium 0°C0.178   
Iron, cast7208153012179
Lead, rolled113253272916
Nitrogen 0°C1.25   
Oxygen 0°C1.43   
Oxy acetylene 4400*  
Pinus Radiata609  6
Silver solder 735  
Easy-flo 630  
Solder Lead 50%9302210  
(Eutectic) Lead 33%/tin 67%8615180  
Snow: fresh961  
             wet compact320   
Stainless Steel 3048080142517193
Stainless Steel 3168080138516193
Steel, low carbon7850135012200
Water: fresh 4°C1000   
Water: fresh 20°C988   
Water: fresh 100°C958   
Water: salt1009-1201   
Zinc: rolled719241929 

* max flame temperature
# glass reinforced polyester GRP expansion = 22
To convert Centigrade to Farenheit.
To convert Farenheit to Centigrade.
C° = F° - 32° x .56
F° = C° x 1.8 + 32°



18.3.1 Thermal Conductivity K 


18.3.1A Thermal Conductivity



Stainless Steel16 
Concrete 0.94
Brick 0.8
Water (20°C) 0.56
Timber (Pine) 0.14
Snow 0.1
Kraft building paper 0.07
Fibreglass 0.035
Rockwool 0.035
Polystyrene 0.035
Air (20°C ) 0.025
Polyurethane (Rigidised) 0.016