As they restrict the free movement of air, their use should be restricted to where they are required for weatherproofing and appearance (such as scribers under window jamb flashings) or for maintaining positive internal pressures, such as in building with a managed internal environment. Profiled closures should be of closed cell type, rather than bitumen impregnated.
In marine areas, corrosion is likely to initiate under apex flashings and under the eaves overhang, regardless of whether profiled foam is used. A high fronted spouting is the best protection against the eaves corrosion. In very severe cases, or where there is a gap between the back of the gutter and the fascia, an eaves flashing of durable material (e.g., aluminium or plastic) can be used to prevent much of the salt build-up on the underside of the roof cladding. (See 8.5.5.4 Eaves Flashing)
For vermin control, a perforated scribed aluminium flashing, or an eaves comb, may be used.
In marine areas, corrosion is likely to initiate under apex flashings and under the eaves overhang, regardless of whether profiled foam is used. A high fronted spouting is the best protection against the eaves corrosion. In very severe cases, or where there is a gap between the back of the gutter and the fascia, an eaves flashing of durable material (e.g., aluminium or plastic) can be used to prevent much of the salt build-up on the underside of the roof cladding. (See Eaves Flashing)
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)
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.
