Ridge and Hip Intersections
Ridge and hip roll top flashings are roll-formed as a standard pitch flashing with a soft edge. When the angle of the flashing is not custom-made to suit the roof, it can result in visible distortion and stress around the fastening if used on pitches steeper than 35°.
Custom-made square top ridging is available for any pitch and width and is available in lengths of up to 8 m. The roll top or square top of a ridging helps accommodate expansion of the roof sheeting and strengthens the ridge.
A vee ridge is not able to support walking traffic and is vulnerable to buckling caused by point load and lateral or longitudinal thermal movement.
A soft-edged flashing can be used for corrugated and low rib trapezoidal profiles, and notched ridging can be used on all trapezoidal, trough or standing seam profiles.
Ridge End
The transition of the ridge and the apex of a hip requires skill to make a neat and weathertight finish and relies on sealant for prolonged weather tightness. An under-flashing such as soft aluminium,underlay, or butyl flexible memberane may be used as a secondary means of waterproofing; but with a tidily executed intersection these are not necessary for weather-proofness.
The gable end termination of roll ridging must be made vermin proof by cutting the ridging back 25 mm and closing it.
As an alternative to continuous ridging on ribbed profiled sheets, use individual rib or ridge caps fitted to each rib after the ribs have been cut and the roof cladding bent over the ridge. Each cap should be accurately fitted and sealed. This method does not allow for free expansion at the ridge of long length roof cladding and restricts natural ventilation of the ceiling cavity. These caps rely on sealant to be made watertight and are only recommended for use at the apex of a roof and when there is sufficient ventilation.
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