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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; 2023-June

19.4 2023 – June 

The following revisions to the NZ Metal Roof and Wall Cladding Code of Practice were published on 1 June 2023.

Substantial change to recommendations:

The main section 3 Structure has been comprehensively revised.

Other important updates:

  • A new clause discusses 12.3 Flashing Buckling in more detail, while the old clause has been renamed Compression Timber.
  • Standing Seam Cladding has been renamed 15.4 Tray Roofing and the entire clause and its sub-clauses have been reviewed.
  • The definition of standing seam roofing (a form of tray roofing installed on solid sarking, using traditional seaming tools) has been clarified.

The rest of the updates consisted of minor corrections and edits.

19.4B Revision Detail - 2023 - June

CategoryClause Number (at time of update)Clause (As of current publication)Details
2 - Editing and rearrangement11 IntroductionUpdated Revisions Message
2 - Editing and rearrangement2.12.1 DefinitionsClarified the definition of Standing Seam Profile.
3 - Substantial change to recommendation33 StructureThe main clause Structure has been comprehensively revised. The revision comprises several changes thtoughout the main clause and sub-clauses
4 - Clause Inserted 3.2 StandardsNew clause to group the standards refered to in 3 Structure in the COP.
0 - Clause Removed3.2GeneralThis clause has been merged with the intorductory clause for 3 Structure.
3 - Substantial change to recommendation3.33.2.1 AS/AZS 1170.2:2011This clause has been revised as part of the overall revision of 3 Structure.
3 - Substantial change to recommendation3.43.2.2 NZS 3604:2011Changed the description of what NZS 3604 includes. Removed the statement that NZS 3604 is location specific.
4 - Clause Inserted 3.2.3 NASH StandardNew clause to mention the NASH Standard in relation to B1/AS1.
4 - Clause Inserted 3.3 PerformanceNew clause. This clause was filled with information previously available in the old clause 3.5.1 Understanding Loads
4 - Clause Inserted 3.3.1 Section PropertiesNew sub-clause discussing how to determine profile strength under load.
3 - Substantial change to recommendation3.153.4 ProfilesThis clause has been revised as part of the overall revision of 3 Structure. Some copy has been moved to 3.5.6 Section Properties
2 - Editing and rearrangement3.15.13.4.1 Corrugate ProfileThe clause has been revised as part of the overall revision of Structure.
2 - Editing and rearrangement3.15.23.4.2 Trapezoidal Profilerevised as part of the overall revision of 3 Structure.
3 - Substantial change to recommendation3.15.53.4.3 Miniature ProfilesDeleted reference to metrical or imperial sizing of miniture profiles.
3 - Substantial change to recommendation3.15.33.4.4 Secret-fixed ProfilesClause renamed and combined with 3.15.4 Standing Seam (removed). Added an illustration
3 - Substantial change to recommendation3.133.4.5 Material GradeContent had been revised and edited as part of the overall revision of 3 Structure.
3 - Substantial change to recommendation3.143.4.6 Material ThicknessThe content of this clause was revised as part of the overall revision of 3 Structure.
4 - Clause Inserted 3.5 LoadsNew introductory clause leading into various clauses dealing with different loads.
3 - Substantial change to recommendation3.53.5.1 Understanding LoadsThe clause has been revised and edited as part of the overall revision of 3 Structure. The illustration of 3.3A Profiled Steel — Flanges and Webs and some content have been moved to 3.4 Profiles. The illustration 3.5.1A Compression, Tensile and Shear Force
0 - Clause Removed3.5.1Point LoadThis clause has been removed as part of the overall revision of 3 Structure. Instead of two clauses
0 - Clause Removed3.5.6Section PropertiesThis clause was removed as part of the overall revision of 3 Structure. The information previous contained in this clause has been spread throughout other clauses.
3 - Substantial change to recommendation3.5.83.5.1.1 ContinuityThe content of this clause was revised and edited as part of the overall revision of 3 Structure. The illustration for 3.5.1.1A Continuity
2 - Editing and rearrangement3.5.43.5.1.2 Load DistributionThe 3.5.1.2 Load Distribution-clause has been revised and edited as part of the overall revision of 3 Structure.
0 - Clause Removed3.5.2Wind LoadThis clause was merged with 3.6.2.1 Wind Load as part of the overall revision of 3 Structure.
0 - Clause Removed3.5.5Yield StrengthThis clause has been assimilated into a new clause
3 - Substantial change to recommendation3.63.6 Types of LoadClauses decribing types of load have been rearranged and revised for clarity and easy of use. Content previously contained to this clause was distributed among it's sub-clauses.
2 - Editing and rearrangement3.6.13.6.1 Point LoadThis clause revised as part of the overall revision of 3 Structure.
3 - Substantial change to recommendation3.73.6.2.1 Wind LoadTwo clauses that previously discussed wind load were merged into one as part of the overall revision of 3 Structure. The content of both clauses were revised and edited to facilitate the merger.
3 - Substantial change to recommendation3.7.13.6.2.1.1 Local Pressure Factor (Kl)Corrected illustration 3.6.2.1.1A Local Pressure for Low-Pitch Roofs and deleted C Local Pressure Factors C.
2 - Editing and rearrangement3.7.23.6.2.1.2 Conversion of Wind Speed To PressureThe content of this clause has been edited as part of a overall revision of 3 Structure.
2 - Editing and rearrangement3.83.6.2.2 Snow LoadsThis contents in this clause has been edited for conciseness as part of the overall revision of 3 Structure.
2 - Editing and rearrangement3.7.33.6.2.3 Roof WeightThe content os this clause has been edited for clarity.
3 - Substantial change to recommendation3.3.13.7 Modes of FailureThe contents of this clause has been edited as part of the overall revision of 3 Structure.
4 - Clause Inserted 3.7.1 Serviceability and Ultimate FailureNewly created clause discussing Serviceability and Ultimate Failure.
3 - Substantial change to recommendation3.5.33.7.2 DeflectionThe content of this clause has been revised as part of the overall revision of 3 Structure. The contents have been merged with 3.5.5 Yield Strength
4 - Clause Inserted 3.7.3 DeformationNew clause made up of merged content from 3.7.2 Deflection and 3.5.5 Yield Strength.
3 - Substantial change to recommendation3.6.23.7.4 Roof TrafficThe content of this has been edited to include a load of 2 kPa applied for accessible roofs.
3 - Substantial change to recommendation3.93.7.5 Dead LoadsThe content of this clause has been edited as part of the overall revision of 3 Structure.
2 - Editing and rearrangement3.13.7.6 Construction LoadsThe content is this clause has been revised as part of the overall revision of 3 Structure. A photo to illustrate rib damage due to construction loads was added.
3 - Substantial change to recommendation3.5.73.7.7 Fatigue and Brittle FailureThe content of this clause has been revised as part of the overall revision of 3 Structure
4 - Clause Inserted 3.8 FastenersNew introductory clause to sub-clauses dealing with structural requirements for fasteners.
3 - Substantial change to recommendation3.113.8.1 Fastener LoadsThe content is this clause has been revised as part of the overall revsion of 3 Structure.
3 - Substantial change to recommendation3.12.1.13.8.2 Steel Purlins This clause has been renamed and merged with 3.12.1 Screw Fasteners and 3.12.1.2 Steel Purlins Thicker Than 1 mm.
3 - Substantial change to recommendation3.12.23.8.4 Pull-over ValuesThe content of this clause has been edited as part of the overall revision of 3 Structure. The copy was revised and the table A Typical Pull over values for crest fixing (serviceability failure) was removed.
2 - Editing and rearrangement3.11.13.8.5 Load-spreading WashersTHis clause has been moved as part of the overall revision of 3 Structure. It now follows 3.8.4 Pull-over Values.
0 - Clause Removed3.12Fastener PerformanceThis clause has been merged with 3.8.1 Fastener Loads.
0 - Clause Removed3.12.1Screw FastenersThis clause has been merged with 3.8.2 Steel Purlins .
0 - Clause Removed3.12.1.2Steel Purlins Thicker Than 1 mmThis clause was merged with 3.8.2 Steel Purlins .
0 - Clause Removed3.15.4Standing SeamClause was combined with 3.4.4 Secret-fixed Profiles.
1 - Minor Errata44 DurabilityFixed typo.
3 - Substantial change to recommendation4.9.44.9.4 Compatibility TableCorrection to the combination of Stainless Steel with Zinc or Zinc coated steel, where runoff from Stainless Steel is not suitable.
Amendment of some material descriptions to more common industry terms (Galvanised steel, Colorsteel®/Colorcote®, Zincalume®).
Addition of Painted Galvanised Steel.
2 - Editing and rearrangement5.5.15.5.1 Valley FixingRearranged layout.
3 - Substantial change to recommendation5.5.65.5.6 Asymmetrical ValleysAdded recommendation for valley baffles where roof pitches excced 10°.
3 - Substantial change to recommendation8.4.38.5.4 Parapet CappingsThis clause was comprehensivly reviewed and all the illustrations were updated.
1 - Minor Errata8.4.48.5.5 Apron FlashingsEdited for clarity. Removed mention of 'hidden flashings' and inserted mention of B2/AS1.
1 - Minor Errata8.4.4.48.5.5.4 Eaves FlashingThe illustration of 8.5.5.4A Gutter-Eaves Flashing has been amended to align with measurements from E2/AS1.
2 - Editing and rearrangement8.88.9 Compression TimberClause renamed. Flashing buckling is discussed in 12.3 Flashing Buckling.
4 - Clause Inserted 12.3 Flashing BucklingNew clause discussing buckling of flashings.
1 - Minor Errata14.1114.11 OverhangDrawing tidy up.
3 - Substantial change to recommendation15.415.4 Tray RoofingThe entire clause 15.4 Tray Roofing
2 - Editing and rearrangement15.4.115.4.1 Tray Roofing MaterialsRenamed the couse to Tray Profile Materials.
2 - Editing and rearrangement15.4.215.4.2 Tray Roofing Profiles15.4 Tray Roofing has been revised and renamed to Self-Support and Standing Seam Profiles.
4 - Clause Inserted 15.4.3 Tray Roofing DesignNew clause discussing standing seam design.
3 - Substantial change to recommendation15.4.315.4.5 Tray FixingsStanding Seam Fixings has been reviewed
1 - Minor Errata15.4.515.4.7 SarkingProvided full terminology for CPD (Control Panel Directive).
2 - Editing and rearrangement15.4.615.4.8 Tray VentilationStanding Seam Ventilation has been renamed Tray Ventilation.
2 - Editing and rearrangement15.4.715.4.9 Standing Seam Roofing Wind LoadsThe clause Standing Seam Roofing Wind Loads has been renamed Tray Roofing Wind Loads.
4 - Clause Inserted 15.4.9.1 Tray Roofing Wind NoiseNew Clause for Tray Roofing Wind Noise.
2 - Editing and rearrangement15.4.815.4.10 Penetrations on Tray RoofingThe clause Penetrations on Standing Seam Cladding has been renamed to Penetrations on Tray Roofing.
3 - Substantial change to recommendation15.4.10.315.4.11 Tray Roof Flashing1. Clause and illustraions have been renamed
2 - Editing and rearrangement15.4.915.4.12 Canning and Purlin CreasingRemoved last line to avoid confusion .
2 - Editing and rearrangement15.4.1015.4.13 Installing Tray CladdingClause renamed
4 - Clause Inserted 15.4.13.2 Commence Laying Tray CladdingNew clause discussing laying of tray cladding.
2 - Editing and rearrangement15.4.10.215.4.13.3 Provision for Expansion — Tray RoofingPhoto from Installing Standing Seam Cladding has been moved to 15.4.13.3 Provision for Expansion — Tray Roofing. Clause has been renamed for consistency.
4 - Clause Inserted 15.4.13.4 Finishing at Ridges and Eaves of Tray RoofingNew clause describing tray roofing sheet end treatment.
1 - Minor Errata17.1.5.117.1.5.1 Allowance for VariationCorrected depreciation factor for clip-fastened products from 30% to 1.3.
4 - Clause Inserted 19.4 2023 – JuneNew clause with revision details for 1 June 2023.