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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 v24.03:Penetrations; Boot-Flashings

9.5 Boot Flashings 

A boot flashing is a proprietary EPDM flashing designed to weatherproof cylindrical penetrations protruding from a roof or wall. The top is trimmed to form a tight weatherproof collar around the penetration, and the base is formed with a series of concentric rings to the underside and a malleable stiffener of aluminium which is dressed to conform to the shape of the roofing profile. It is generally top-fixed to the roof surface with screws or rivets, and sealant.

The Profiled Metal Roofing COP allows pipe penetration flashings to be fitted directly to the profile or on to an over flashing. Pitch limitations depend on the method used and the cladding profile.

Direct-fixed options are pitch sensitive. When laid directly on to the profile at too low a pitch, they will entrap water rather than allow it to discharge over the profile crests that they traverse. The practical limits of direct-fixed boot flashings that cross an entire pan are 8° for standard corrugated and 10° for low rib trapezoidal products. Where the base of a boot does not obstruct a pan it can be direct-fixed to the minimum pitch for that profile.

Direct fixed applications for high rib trapezoidal profiles and trough sections vary according to the profile, and the size and position of the penetration. For these applications, the manufacturer should be consulted or the flashing can be attached to an over flashing, or a top fixed soaker type can be used.

Where the penetration is wide such as a chimney flue casing, and the penetration is far from the apex, soaker flashings may be used where the profile ribs are cut back so water can divert into the adjacent pan.

Where overall width is not a constraint, directly fixed boot flashings should be installed with their edges diagonal to the fall of water. Where this is not practical, they may be laid square at pitches of 10° or more.

Where boot flashings traverse a lap, the lap must be fully sealed or other actions must be taken to avoid leaks through capillary action. Where possible the fixing of a boot flashing over a lap should be avoided

The vertical sections of a boot flashing must not constrict the free flow of water. Where more than 50% blockage of the pan occurs other penetrations must be considered, or catchment calculations of the capacity of the remaining pan area should be made. (See 5.4.7 Gutter Capacity Calculator)



9.5.1 Boot Flashings to an Over Flashing 

Boot flashings fitted to an over flashing are acceptable at pitches down to the minimum of that allowed for the profile. Typically, this is 8° for standard corrugated, and 3° for trapezoidal and trough sections. These boot flashings must be fixed diagonally to the fall of the roof at pitches below 10°.

Over flashings can be continuous to the apex, or terminate with a soaker at the upper edge.

9.5.2 Other Applications for Boot Flashings Plant Room And Conduit Penetrations 

Where flexible power conduits or telecommunication cables are required to penetrate the roof cladding, accessibility can be improved by using P.V.C pipe fittings and an E.P.D.M. flashing to weather a number of conduits.

Cable penetration flashings must be goose-necked. It is not acceptable to exit cables through a vertical flashing such as a boot flashing where sealant is the only barrier to water leakage. PVC and E.P.D.M Flashing

This flashing should be fixed next to the purlin for support.


Safety bollards for fall arrest anchorages are required where regular maintenance is required, and these can also be weathered by E.P.D.M. flashings. Mechanical Services 

Where plant room supports are required to penetrate the roof cladding, the designer should provide the support framing from Circular Hollow Sections (CHS) in preference to Rectangular Hollow Sections (RHS) or other hot rolled steel sections, because it is easy to flash the CRS with E.P.D.M. flashings. This procedure allows the E.P.D.M. flashings to be slid over the pipe framing during erection, and avoid the necessity of using retrofitting types.

The support framing should be in place, but below the top of the purlin, before installing the roof cladding. That allows the cladding installation to proceed without having to weatherproof multiple penetrations at the same time.


(optional caption)

Proprietary support systems are available for lightweight support through to the purlins.


These types of supports provide clearance for cleaning but should not create an unwashed area underneath them.




9.5.3 Flush Penetrations 

Penetrations such as roof window may be mounted flush with the crests of the roofing profile.  In such cases, the side flashing onto the roof shall be the same as required for a barge cover. The flashing termination onto the roof window shall be as per window manufacturers requirements