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Disclaimer

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.

Scope

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 v24.03:Revision-History; 2018-November

2018 – November

19.21 2018 – November 

The NZ Metal Roof and Wall Cladding Code Practice (COP), has been updated effective 1 November 2018.

In this Update no recommendations have been altered that would require changes to existing projects in progress

Summary of Changes in this Update

  • The previous External Moisture, Flashings and Penetrations sections have been updated to closer reflect the requirements of NZBC Clause E2 – External Moisture.
    All clauses and sub-clauses in these sections have been substantially revised and drawings updated to show details more clearly.

  •  Other updates consist of Category 1 – minor errata corrections to spelling, and grammar and layout.

19.21A

Category Clause Number (at time of update) Clause (As of current publication) Details
2 - Editing and rearrangement 4.5.2 4.5.2 Sea Spray Moved copy dealing with corrosion from "Eaves Flashing" to "Sea Spray".
1 - Minor Errata 4.11.8 4.10.8 Microcracking Correction to comparative scale of illustrations
0 - Clause Removed 6.1.1 7.1.1 Conduction  
4 - Clause Inserted 6.1.1 6.1.1 E2 Objective E2 Objective under NZBC Clause E2 (Extract)
4 - Clause Inserted 6.1.2 6.1.2 E2 Functional Requirement New clause to follow E2 Objective.
4 - Clause Inserted 6.1.3 6.1.3 E2 Performance Requirements New clause to follow "Functional Requirement".
0 - Clause Removed 6.1 7.1 Heat Clause removed, see 7.3 Thermal Expansion And Contraction.
4 - Clause Inserted 6.1 6.1 NZBC Clause E2 External Moisture (Extract) New Clause under External Moisture — General.
4 - Clause Inserted 6.2.1 6.2 Compliance New 2nd level clause to follow "Acceptable Solution NZBC E2/AS1"
0 - Clause Removed 6.2.2.1 7.4.2.1 Profile Strength Subject now discussed in 7.3 Thermal Expansion And Contraction.
2 - Editing and rearrangement 6.2.2.3 8.10 Flashing Expansion Details Completely revised clause.
2 - Editing and rearrangement 6.2.2.4 8.10.2 Building Expansion Joints Clause duplicated.
4 - Clause Inserted 6.2 6.2 Acceptable Solution NZBC E2/AS1 New 2nd level clause to follow "Limits on Applications. "
0 - Clause Removed 6.3 8.15 Sealing Washers  
4 - Clause Inserted 6.3 6.3 Related Topics New 1st level heading under "External Moisture — General"
3 - Substantial change to recommendation 6.5.2 7.1.2 Runoff Clause completely revised.
0 - Clause Removed 6.5.3 7.2.3 Snow Clause removed, combined with 5.4 Snow.
0 - Clause Removed 6.5.4 7.2.4 Hail Clause removed combined with 5.4.1 Hail.
2 - Editing and rearrangement 6 6 External Moisture Overview Clause completely revised to reflect all four COP clauses dealing with E2 External Moisture.
3 - Substantial change to recommendation 7.1.1 7.1.1 Minimum Roof Cladding Pitch Clause completely revised.
0 - Clause Removed 7.1 7.1 Radiation  
0 - Clause Removed 7.1 8.1 Purpose Clause removed, included in 8 External Moisture Flashings.
2 - Editing and rearrangement 7.2.1 8.1.1 Flashing Durability Completely revised and renamed clause renamed (previously "compatibility").
0 - Clause Removed 7.2 7.2 Convection  
2 - Editing and rearrangement 7.2 7.1 Roof Pitch Clause completely revised. To be the first sub-clause under External Moisture — Cladding.
2 - Editing and rearrangement 7.2 8.1 Flashing Materials Completely revised clause
4 - Clause Inserted 7.2 7.2 Fastening Roofing New sub-clause to be inserted at the end of Roof Pitch under External Moisture — Cladding.
3 - Substantial change to recommendation 7.3.1 7.3.1 Temperature Range Completely Revised and rewritten. To follow "Thermal Expansion and Contraction" under the new level 1 Clause: "Cladding"
4 - Clause Inserted 7.3.1 8.4.4 Flashing Laps Completely revised and shortened clause.
3 - Substantial change to recommendation 7.3.2 7.3.2 Roof Cladding Expansion Provisions Completely Revised and Rewritten. To follow "Steel Cladding Temperature Ranges" in "Thermal expansion and Contraction" under new Level 1 Clause: "Cladding".
2 - Editing and rearrangement 7.3 7.3 Thermal Expansion And Contraction Completely revised and redone. To be moved under new level 1 Clause: External Moisture Cladding.
0 - Clause Removed 7.4.1.1 8.6.1.1 Ridge - Hip Intersections Clause incorporated into 8.5.1 Ridge And Hip.
2 - Editing and rearrangement 7.4.2 8.5.3 Barge And Verge Completely revised clause.
0 - Clause Removed 7.4.2.1 8.6.2.1 Internal Barge Flashing Incorporated into parent clause.
2 - Editing and rearrangement 7.4.2.2 8.5.3.1 Ridge – barge Intersections Completely revised clause.
2 - Editing and rearrangement 7.4.4 8.5.5 Apron Flashings Completely revised clause
2 - Editing and rearrangement 7.4.4.1 8.5.5.1 Parapet And Apron Capping Terminations Completely revised clause.
2 - Editing and rearrangement 7.4.4.3 8.5.5.3 Step Apron Completely revised clause. Drawings updated.
2 - Editing and rearrangement 7.4.4.4 8.5.5.4 Eaves Flashing Completely revised and renamed clause. (Previously "Gutter Apron"). Drawing updated.
0 - Clause Removed 7.4.5 8.6.5 Valley Flashings Clause removed. Valleys are discussed in "Roof Drainage".
2 - Editing and rearrangement 7.4.6 8.5.6 Curved Flashings Completely revised clause.
2 - Editing and rearrangement 7.4.6.1 8.5.6.1 Lockseamed Flashings Revised clause. Information added.
0 - Clause Removed 7.4.6.2 8.6.6.2 Jennied Flashings Clause removed — all references to "jennying" has been removed from "Flashings".
4 - Clause Inserted 7.4.6.3 8.5.6.2 Crimped Flashings New clause under 8.5.6 Curved Flashings.
0 - Clause Removed 7.4.7 8.6.7 Soffit Flashings Clause removed.
2 - Editing and rearrangement 7.4 7.4 End Laps Clause completely revised.
2 - Editing and rearrangement 7.4 8.5 Flashing Types The last line edited.
0 - Clause Removed 7.5.1 8.12.1 Unpainted Metal Cladding Clause removed.
0 - Clause Removed 7.5.2 8.12.2 Ventilation and Cavities Clause removed.
0 - Clause Removed 7.5.3 8.12.3 Window and Door Flashings in Metal Cladding  
0 - Clause Removed 7.5.4 8.12.4 Horizontal Metal Cladding  
0 - Clause Removed 7.5.5 8.12.5 General Principles  
0 - Clause Removed 7.5.6 8.12.6 Flush Window Flashings Clause removed.
0 - Clause Removed 7.5.7 8.12.7 Recessed Window Flashings Clause removed.
0 - Clause Removed 7.5.8 8.12.8 Butt Window Flashings Clause removed.
0 - Clause Removed 7.5.9 8.12.9 Flashings For Vertical Cladding  
0 - Clause Removed 7.5.10 8.12.10 Alternative Flashing Designs  
2 - Editing and rearrangement 7.5 8.11 Metal Wall Cladding Flashings Completely revised and renamed clause.
0 - Clause Removed 7.6 8.13 Flashings For Vertical Cladding Clause removed.
0 - Clause Removed 7.7 8.14 Flashings For Horizontal Corrugate Cladding Clause Removed.
2 - Editing and rearrangement 7.8.1 8.6.1 Primary Fasteners Completely revised and shortened clause.
2 - Editing and rearrangement 7.8.2 8.6.2 Secondary Fasteners Completely revised clause.
0 - Clause Removed 7.8.3 8.7.3 Secret Fixing Clips Clause deleted.
2 - Editing and rearrangement 7.8.4 8.6.3 Flashing Cleats  
4 - Clause Inserted 7.8.5 8.6.4 Seams Split the drawing into eight individual drawings, for improved layout.
2 - Editing and rearrangement 7.8 8.6 Fastening Flashings Clause renamed.
0 - Clause Removed 7.9.1 8.8.1 Properties Clause removed. Discussed in 8.7 Sealants.
2 - Editing and rearrangement 7.9.2 8.7.1 Methods Of Sealing Revised clause
2 - Editing and rearrangement 7.9.3 8.7.2 Surface Preparation Clause shortened.
0 - Clause Removed 7.9.5 8.8.5 Sealed Laps Clause removed see: A Sealed End Lap.
0 - Clause Removed 7.9.6 8.8.6 Strip Sealants Clause removed.
0 - Clause Removed 7.9.7 8.8.7 Soldered Joints Clause Removed.
2 - Editing and rearrangement 7.9 8.7 Sealants Completely revised clause.
0 - Clause Removed 7.10.1 8.9.1 Vented Fillers  
2 - Editing and rearrangement 7.10.2 8.8.1 Soft Edging Revised and renamed clause.
2 - Editing and rearrangement 7 8 External Moisture Flashings Completely revised clause.
4 - Clause Inserted 7 7 External Moisture Roofing New Level 1 clause.
0 - Clause Removed 8.1 9.1 General Clause removed. General discussion incorporated in the introduction.
2 - Editing and rearrangement 8.2.1 9.2 Additional Support Completely revised and renamed clause.
2 - Editing and rearrangement 8.2.2 9.3 Penetration Durability and Compatibility Completely revised and renamed clause.
0 - Clause Removed 8.2.3 9.5 Corrosion Incorporated into "9.3 Penetration Durability and Compatibility".
0 - Clause Removed 8.2.4 9.5.1 Catchment Clause removed.
0 - Clause Removed 8.2.5 9.5.2 Obstruction Clause removed.
0 - Clause Removed 8.2.6 9.5.3 Discharge Capacity Clause removed, see 
0 - Clause Removed 8.2.7 9.5.4 Sealing Clause removed. (Information is repeated in 8 External Moisture Flashings)
0 - Clause Removed 8.2.8 9.5.5 Alternative Materials Clause removed, see 8.8.1 Soft Edging.
2 - Editing and rearrangement 8.2 8.2 Flashing Design Completely revised and shortened clause
2 - Editing and rearrangement 8.2 9.1 Penetrations Minimum Pitch Completely revised and renamed clause.
0 - Clause Removed 8.3.1 9.7.6 Nomenclature Clause removed. More details added in 9.4 Penetration Design.
0 - Clause Removed 8.3.2 9.7.7 Diverter Or Cricket Designs Clause removed in favour of more detailed drawings in Penetration Flashing Design.
0 - Clause Removed 8.3.3 9.7.8 Penetration Flashing Installation Clause removed in favour of more detailed drawings in "Penetration Flashing Design".
0 - Clause Removed 8.3.4 9.7.9 Laps Clause removed, see 7.4 End Laps.
0 - Clause Removed 8.3.5 9.7.10 Details Clause removed. See 9.4.2.5 Penetration Flashings on Corrugated Profiles.
0 - Clause Removed 8.3.7 9.7.11 Type A Soaker  
0 - Clause Removed 8.3.8 9.7.12 Type B Watershed Clause removed. New Details available.
0 - Clause Removed 8.3.9 9.7.13 Type C Tapered Clause removed. New flashing details provided.
0 - Clause Removed 8.3.10 9.7.14 Type D Tray Clause removed. New Flashing details provided elsewhere.
2 - Editing and rearrangement 8.3 8.4 Flashing Cover Completely revised clause. Drawings updated for clarity.
2 - Editing and rearrangement 8.3 9.4 Penetration Design Revised clause.
2 - Editing and rearrangement 8.4.1 9.5.2.1 Plant Room And Conduit Penetrations Completely revised clause.
2 - Editing and rearrangement 8.4 8.2.1 Flashing Edges Completely revised clause. Drawings updated.
2 - Editing and rearrangement 8.5.1 8.5.1 Ridge And Hip Completely revised clause.
2 - Editing and rearrangement 8.5.3 8.5.4 Parapet Cappings Completely revised clause.
3 - Substantial change to recommendation 8.5.4.2 8.5.5.2 Change Of Pitch Completely revised clause. Drawings updated.
0 - Clause Removed 8.5 9.9 Dormer Junctions Clause removed.
4 - Clause Inserted 8.7.3 8.7.3 Sealant Extrusion And Placement Updated drawing: "Applying Sealant".
4 - Clause Inserted 8.8.2 8.8.2 Notched Edging New Clause to follow "Soft Edging", under "Profile Closures". 
2 - Editing and rearrangement 8.8 8.8 Profile Closures Completely revised clause.
4 - Clause Inserted 8.9 8.9 Compression Timber Inserted new clause.
4 - Clause Inserted 8.32 19.21 2018 – November November Update Message added
2 - Editing and rearrangement 8 9 External Moisture Penetrations Completely revised and renamed clause.
4 - Clause Inserted 9.3 9.2.1 Penetrations Safety New sub-clause under "Additional Support".
4 - Clause Inserted 9.5.1 9.4 Penetration Positioning New Clause.
4 - Clause Inserted 9.5.2 9.4.1 Penetration Back Flashings New Clause.
4 - Clause Inserted 9.5.3 9.4.1.1 Over-Flashed (Watershed) Back Flashings New Clause
4 - Clause Inserted 9.5.4 9.4.1.2 Under-Soaker Back Flashings New Clause
4 - Clause Inserted 9.5.5 9.4.2 Curb Design New Level 2 Clause.
4 - Clause Inserted 9.5.5.1 9.4.2.1 Level Back Curbs New level 3 Clause under 9.4.2 Curb Design.
4 - Clause Inserted 9.5.5.2 9.4.2.2 Arrowhead Back Curbs New 3rd level clause under 9.4.2 Curb Design.
4 - Clause Inserted 9.5.5.3 9.4.2.3 Cricket Back Curbs New level 3 Clause under 9.4.2 Curb Design.
2 - Editing and rearrangement 9.5.6 9.4.2.5 Penetration Flashings on Corrugated Profiles Revised and renamed clause.
4 - Clause Inserted 9.6.1 9.5.1 Boot Flashings to an Over Flashing New Clause
4 - Clause Inserted 9.6.2 9.5.2 Other Applications for Boot Flashings New Clause
4 - Clause Inserted 9.6.2.2 9.5.2.2 Mechanical Services New clause
2 - Editing and rearrangement 9.6 9.5 Boot Flashings Revised and renamed clause.
4 - Clause Inserted 9.7 9.5.3 Flush Penetrations New clause
2 - Editing and rearrangement 16.7 17.7 Wind and Point Load Testing