COP v3.0:flashings; profile-closures

8.8 Profile Closures 

Profiled closures are available for all profiles. As they restrict the free movement of air, their use should be restricted to where their use is required for weatherproofing or other reasons, such as maintaining internal pressures.

High fronted spoutings or scribed, ventilated metal closures are the preferred methods of preventing ingress of wind-blown moisture; and for vermin, an eaves comb which self-adapts to any profile.

Profile closures should be a closed cell type rather than bitumen impregnated open cell foam.

Filler blocks should be used compressed between the sheets and supports or flashing and should be secured by the cladding fastener or adhesive sealant

8.8.1 Soft Edging 

To prevent the ingress of weather, dirt, or birds, it is common practice in New Zealand to close the openings created by the pan and ribs of profiled sheets using notched metal flashings or soft edging. Lead was the traditional material for this application, but as it is incompatible with AZ coatings, soft aluminium edging or composite materials are offered as an alternative.

Proprietary soft edging is available for corrugated and low trapezoidal profiles, consisting of an expandable aluminium mesh with a flexible backer.

All soft-edged flashings should be primed and colour painted before installation — but the preferred option is for the paint finish on soft edges to be factory painted under controlled conditions.

Soft-edged flashings are available in a partially-backed form to facilitate passive ventilation at the apex. (See  Internal Moisture)

 

8.8.2 Notched Edging 

Where the profile height exceeds 30 mm, a notched flashing is the preferred option.

All scribed edges should have clearance to avoid damaging the coating of the roof sheet. The scribed metal edge of any flashing must have a clearance of 2 mm to 5 mm.