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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 the good design of flashings can ensure weathertightness in extreme conditions.

Water backup against vertical faces caused by high velocity, localised wind eddies, especially inside parapets and at the bottom edge of walls, are all vulnerable details. Pressure equalisation-designs and 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.)
 
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