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Minimum Roof Cladding Pitch

Minimum Pitch for Generic Metal Roofing

ProfileMin HeightMin PitchCheck Capacity
after run of...
Trapezoidal
Asymmetrical		204°20 m
273°40 m
363°65 m
Trapezoidal
Symmetrical		204°15 m
304°25 m
Secret Fix303°60 m
253°30 m
Standing Seam303°85 m
253°35 m
Corrugate16.58°15 m
214°20 m
353°65 m

 

Minimum pitches quoted in this table refer to roof cladding pitch and not the building design roof pitch.

Buildings designed with widely spaced purlins and widely spaced portal frames may require an increased design pitch to comply with the minimum recommended as-laid pitches.

Low-pitched roofs require greater attention to flashing details. The ability of side laps or end laps to withstand water penetration also becomes more critical at low pitches, but a good design of flashings can ensure weathertightness in extreme conditions.

Water buildup on vertical surfaces due to intense localised wind patterns, particularly around parapets and along the lower edges of walls, creates vulnerable areas. Wind baffles are more effective in preventing water ingress than increasing the flashing cover width.

Exceptions to the Minimum Recommended Roof Cladding Pitch requirements:

 
  • Curved roofs, where, by design, the minimum pitch at the crest is always less than the prescribed minimum pitch. In these cases, the pitch at the eaves must comply with the profile’s minimum pitch, and the pitch at the upper end of a terminated arc must be a minimum of 3°.  (See Curved Roofs).
  • The back curbs of penetration flashings where the minimum pitch is 1.5°. (See Penetrations).
  • Reroofing trough section roofs at less 3°, where satisfies the requirements and considerations of Building work that does not require a building consent (Exemptions Guidance for Schedule 1 of the Building Act 2004) Fifth edition August 2020. More information is available at   Building work that does not require a building consent, Section 1.1 General repair, maintenance and replacement of building parts (page22).
    Clause: 
    007_001_001_000_000_000_000_000_000
    Clause Number: 
    7.1.1
    /cop/roofing/roof-pitch#minimum-roof-cladding-pitch
    Revision Category: 
    3 - Substantial change to recommendation
    Revision Detail: 

    Added an exception to Exceptions to the Minimum Recommended Roof Cladding Pitch requirements regarding guidance for Reroofing trough section roofs at less than 3°.

    Draft Clause: 
    006_005_001_000_000_000_000_000_000