NZ METAL ROOF AND WALL CLADDING

COP v3.0:installation; | NZ Metal Roofing ManufacturersVERSION 3.0 / February 2019
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1.1 Disclaimer and Copyright 1.2 Scope 1.3 Related Documents 1.4 Acknowledgements 1.5 Disputes
2 Glossary
3 Structure
3.1 NZBC Clause B1 (Extract) 3.2 General 3.3 AS/AZS 1170.2:2011 3.4 NZS 3604:2011 3.5 Understanding Loads 3.6 Types of Load 3.7 Wind Load 3.8 Snow Loads 3.9 Dead Loads 3.10 Construction Loads 3.11 Fastener Loads 3.12 Fastener Performance 3.13 Material Grade 3.14 Material Thickness 3.15 Profile Shape 3.16 Maximum Span and Fastener Requirements
4 Durability
4.1 NZBC Clause B2 4.2 Metal Corrosion 4.3 Metal Performance 4.4 Sacrificial and Barrier Protection 4.5 The Environment 4.6 Environmental Categories 4.7 Special Climates 4.8 Biological Corrosion 4.9 Paint Durability 4.10 Compatibility
NZ Metal Roof And Wall Cladding Code Of Practice v3.0
2NZ Metal Roof And Wall Cladding Code Of Practice v3.0 © New Zealand Metal Roofing Manufacturers Inc 2018
This is a controlled document. This copy of the Code Of Practice was issued 1 February 2019, and the next issue is due 1 May 2019. The Online version of this document is the most up-to-date and in the case of conflict the Online version prevails over any saved or printed version.
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4.11 Other Causes of Corrosion 4.12 Inert Catchment 4.13 Ponding 4.14 Pitting Corrosion 4.15 Swarf Staining and Cut Edge Corrosion 4.16 Clearances 4.17 Materials 4.18 Organic Coating 4.19 Accessories
5 Roof Drainage
5.1 NZBC: Clause E1 — Surface Water 5.2 Roof Drainage Design 5.3 Rainfall Intensity 5.4 Snow 5.5 Gutters 5.6 Valley Gutters 5.7 Downpipes 5.8 Sumps
6 External Moisture Overview
6.1 NZBC Clause E2 External Moisture (Extract) 6.2 Acceptable Solution NZBC E2/AS1 6.3 Related Topics
7 External Moisture Roofing
7.1 Roof Pitch 7.2 Fastening Roofing 7.3 Thermal Expansion And Contraction 7.4 End Laps
8 External Moisture Flashings
8.1 Flashing Materials 8.2 Flashing Design 8.3 Flashing Cover 8.4 Flashing Types 8.5 Fastening Flashings 8.6 Sealants 8.7 Profile Closures 8.8 Flashing Buckling 8.9 Flashing Expansion Details 8.10 Metal Wall Cladding Flashings 8.11 Safety
9 External Moisture Penetrations
9.1 Penetrations Minimum Pitch
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10 Roof Ventilation
10.1 NZBC Clause E3 Internal Moisture. 10.2 Condensation 10.3 Building Airtightness 10.4 The External Environment 10.5 The Living Environment 10.6 Ventilation 10.7 Underlay 10.8 Wall Underlay
11 Natural Light
11.1 Clause G7 NZBC 11.2 Materials 11.3 Types Of Roof Lights 11.4 Light Transmission 11.5 Weathering And Durability 11.6 Loadings 11.7 Thermal Expansion
12 Fitness For Purpose
12.1 Roof Noise 12.2 Purlin Creasing 12.3 Oil Canning 12.4 Colour Differential 12.5 Transport, Handling And Storage of rooflights
13 Site Practice
13.1 Safety 13.2 Transportation 13.3 Handling 13.4 Acceptance Of Materials 13.5 Roof Loading 13.6 Walking On Roofs 13.7 Completion 13.8 Tools Of The Trade
14 Installation
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14.4 Secondary Fasteners 14.5 Fixing 14.6 Installation 14.7 Re-Roofing 14.8 Translucent Sheeting 14.9 Fixing Aluminium Sheeting 14.10 Metal Roof Defects
15 Other Products
15.1 Curved Roofs 15.2 Solar Units 15.3 Pressed Metal Tiles 15.4 Standing Seam Cladding 15.5 Insulated Panels
16 Maintenance
16.1 Improved Durability 16.2 Normal Maintenance 16.3 Scheduled Maintenance 16.4 Preventative Maintenance 16.5 Special Maintenance 16.6 Inspection 16.7 Washing 16.8 Overpainting 16.9 Material Selection 16.10 Drinking Water 16.11 Storage
17 Testing
17.1 Scope 17.2 Commentary On Part 16.1 17.3 General Methods Of Testing Sheet Roof And Wall Cladding 17.4 Commentary On 16.3 17.5 Wind load Span Graphs 17.6 Specific Methods Of Testing Sheet Roof And Wall Cladding 17.7 Wind and Point Load Testing 17.8 Method: Resistance To Wind Pressures For New Zealand 17.9 Commentary On Section 16.6
18 Useful Information
18.1 Conversion Factors 18.2 Roof Pitch Tangent 18.3 Material Density, Melting Point, Expansion And Modulus 18.4 Decadic Number System 18.5 Geometry And Mensuration 18.6 Velocities 18.7 Cricket Penetration Patterns
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18.8 Sheet Metal Work For Roofing Contractors.
19 Revision History
Policy for Updates to NZ Metal Roof and Wall Cladding Code Practice. 19A Revision Categories 19.1 2019 – February 19.2 2018 – November 19.3 2018 – October
1 Introduction The NZ Metal Roof and Wall Cladding Code of Practice (COP) is published by NZ Metal Roofing Manufacturers Inc. (MRM), to provide:
acceptable trade practice for the fixing of metal roof and wall cladding and accessories. prescriptive detailing for designers and sets a benchmark for the standard of detailing and workmanship required over and above that required to comply with the NZBC.
The COP does not describe or dismiss alternative methods, which may need specific acceptance by the Building Consent Authorities.
It is published in accordance with current technology, materials, and building codes. The COP will be periodically updated to reflect changes in legislation and standards or improvements in technology and available materials.
The most current Code of Practice is available on the MRM website, www.metalroofing.org.nz/cop, as Code of Practice Online (MRM COP Version 3).
The most recent Update to the COP was on 1 February 2019.
In this update, no recommendations have been altered that would require changes to existing projects in progress.
Summary of Changes in this Update
Two new clauses were added in Structure to discuss Material Grade and Material Thickness. Two new, separate, clauses under Clearances, discuss Ground Clearance and related Site Management in more detail. Clauses dealing with Screw Fasteners fixing to specific purlin types re-ordered for clarity. New drawing to show recommended Penetration Type at Recommended Position. Other updates consist of Category 1 – minor errata corrections to spelling, and grammar and layout.
See 2019 – February for details of the changes in this Update.
1 INTRODUCTION 1 1
1.1 Disclaimer and Copyright
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.
This is the current online Code of Practice, published in December 2017.
Sections marked as Version 3.0 contains new, substantially updated information and interactive tools. Sections marked as V2.3 denotes a revised edition of V2.2 (published in November 2012)
New Zealand Metal Roofing Manufacturers Inc. (NZMRM) periodically updates the information contained in this Code.
Before using this Code, please refer to the New Zealand Metal Roofing Manufacturers Inc. website (www.metalroofing.org.nz) for the most recent updates on information contained in this Code.
1 INTRODUCTION 1 1.1 DISCLAIMER AND COPYRIGHT 1 1
1.1 8NZ Metal Roof And Wall Cladding Code Of Practice v3.0 © New Zealand Metal Roofing Manufacturers Inc 2018
1.2 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.
1 INTRODUCTION 1 1.2 SCOPE 2 1
1.3 Related Documents
Standard Year Title NZ 2295 2017Pliable, permeable building underlays. (either NZS 2295 2017 or NZS 2295 Amendment 1 2017) NZS 3602 2003Timber and wood based products for use in building. NZS 3603 1993Amendment 4 2005 Timber Structures Standard. NZS 3604 2011Timber Framed Buildings. AS/NZS 1170.0
2002Amendment 5 2011 Structural design actions. General Principles. Commentary to Parts 0, 1 and 2.
AS/NZS 1170.1
2002Amendment 2 2009 Structural design actions. Permanent, imposed and other actions.
AS/NZS 1170.2
AS/NZS 1170.3
2013Amendment 1 2007 Structural design actions. Snow and ice actions
AS 1562.1 1992Design and Installation of sheet roof and wall cladding – Part 1 Metal AS 1562.3 2006Design and Installation of sheet roof and wall cladding – Part 3 Plastic (was AS/NZS 1562.3 1996) AS/NZS 1734
1997Aluminium and aluminium alloys - Flat sheet, coiled sheet and plate
AS/NZS 2728
AS/NZS 4257
1994/97 Plastic roof and wall cladding materials. Parts 0-9 Methods of Test.
AS/NZS 4389
2005Amendment 1 2010. Cold-formed Steel Structures.
AS 1391 2007(R2017) Metallic materials - Tensile testing at ambient temperature AS 1397 2012Continuous hot-dip metallic coated steel sheet and strip - Coatings of zinc and zinc alloyed with
aluminium and magnesium AS 3566.1 20021. General requirements and mechanical properties AS 3566.2 20022. Corrosion resistance requirements. (Withdrawn) AS 4256 2006Plastic roof and wall cladding materials. (Now AS only previously AS/NZS 4256 1994). Parts 1-5.
Plastic materials. BS 1470 1987Specification for wrought aluminium and aluminium alloys for general engineering purposes.
(Replaced by 9 EN Standards) See AS 1734 BS 2870 1980Specification for rolled copper and copper alloys. (Replaced by EN standards) BS EN 988 1987and BS EN 1179 2003 Specification for zinc alloy sheet and strip ISO 9223 2012Corrosion of metals and alloys. Corrosivity of atmospheres - Classification. ISO 9224 2012Corrosion of metals and alloys. Corrosivity of atmospheres - Guiding values for the corrosion
categories.
1 INTRODUCTION 1 1.3 RELATED DOCUMENTS 3 1
ISO 9225 2012Corrosion of metals and alloys -- Corrosivity of atmospheres -- Measurement of environmental parameters affecting corosivity of sites
ISO 9226 2012Corrosion of metals and alloys -- Corrosivity of atmospheres -- Determination of corrosion rate of standard specimens
AS/NZS 3500.3
2015Stormwater drainage
AS/NZS 2179.1
2014Metal shape or sheet rainwater goods, and metal accessories and fasteners
AS 2180 1986Metal rainwater goods - Selection and installation HB 114 1998Guidelines for design of eaves and box gutters AS 4312 2008Atmospheric corrosivity zones in Australia HB 39 2015Installation code for metal roofing and wall cladding AS/NZS 2312
2002Guide to the protection of structural steel against atmospheric corrosion by the use of protective coatings
AS 4040.0 1998Methods of testing sheet roof and wall cladding Introduction, list of methods and general
requirements AS 4040.1 1998Methods of testing sheet roof and wall cladding Resistance to concentrated loads AS 4040.2 1998Methods of testing sheet roof and wall cladding Resistance to wind pressures for non-cyclone
regions AS/NZS 4200.1
AS 4200.2 2017Pliable building membranes Part 2: Installation
Standard Year Title
1 INTRODUCTION 1 1.3 RELATED DOCUMENTS 3 1
1.4 Acknowledgements
The MRM Technical Committee continuously update this COP, which was originally authored by Stuart Thomson.
Our thanks to advisors, designers and trades people for their input.
1 INTRODUCTION 1 1.4 ACKNOWLEDGEMENTS 4 1
1.5 Disputes
Under the provisions of the Building Act and the NZBC, a contractor who undertakes to do work on a building implies that he can produce an effective and sound result which will fulfil its intended purpose.
There is a customer expectation, backed by consumer legislation, that the finished work will leave the building weathertight, and the work done will comply with the NZBC and will be to a standard that is described as “acceptable trade practice”.
“Acceptable trade practice” and “good trade practice” for the Roofing Industry are both described and contained in this Code of Practice. In addition to any contractual or verbal offer there may also be a written obligation given in the form of a warranty. See Material Selection
All contractors should ensure that materials they use comply with the requirements and specifications contained within this Code of Practice. All suppliers’ or manufacturers’ product literature should be dated; and where superseding previous literature the dates should be referenced. The user must ensure that suppliers or manufacturers product literature is the latest version published.
Contractors must be satisfied that the product as described in the product literature is acceptable to the Territorial Authority, and contractors must be aware of their liability under law and the contractual documents they have signed or agreed to.
Customer expectation is supported by law that states that the material and product used must be fit for its intended purpose, and the liability of each of the parties is assessed on their ‘failure to warn that the product would not fulfil a perceived function".
Poor workmanship is a common cause of dispute and it is often given as the reason for non-payment between the sub-contractor and contractor or owner. This Code of Practice provides a standard of workmanship and a benchmark for arbitration.
It is in the interest of all parties to avoid the cost and delay of litigation and although there are other voluntary ways to settle disputes, they all require some compromise by those concerned.
One voluntary method is negotiation by calling a site meeting where all interested parties can air their grievances across a table and draw up a programme of rectification and reach an agreement over responsibilities and payment.
Any agreement must be recorded, signed and state what is to be done, how much is to be paid, by whom, by when, and how it will be accepted and checked. If no agreement…

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