COP v3.0:flashings; profile-closures

7.10 Profile Closures 

 

Profile closures, also referred to as filler blocks or profile foam fillers, are accessories capable of being compressed for retention and providing a means of closing the rib or pan cavities at a ridge, where they are inserted between the roof cladding and ridging or flashing. (see drawing 5.7.B)

When profile closures are used at the eave, they should be a closed cell and a vented or perforated type to allow some ventilation.

 

 

 

Filler blocks exclude wind, rain, snow, wind driven debris, insects, rodents and birds. Bird damage to the closures caused by pecking or other vermin damage can be minimised by using scribed metal flashings or caps in place of foam fillers or to cover the fillers. Filler blocks can be adhered to metal profiles before or after fixing by using a spray contact adhesive or heat resistant double-sided tape.

Closures are manufactured from closed cell plastic infill strips to match most metal and plastic cladding profiles and are available in most profiles in 'over and under' configurations.

Closures should be used as a wind baffle and should not be used as a prime source of preventing water entering a gap, as the retained moisture will cause corrosion.

They should be used compressed between the sheets and supports or flashing and should be fastened or adhered to the cladding by tape or adhesive to avoid falling out or rolling over. They should be used on all roof pitches below 10° when the wind design load is high or very high.

Closures should be placed midway in the cover gap between the stopend and the front of the flashing which avoids water ingress by providing an air gap baffle to reduce the pressure differential.

Although greater durability can be expected, minimum durability is estimated to be 15 years for products made of closed cell cross-linked polyethylene and up to 20 years for closed cell EPDM, which also has good UV resistance and nil water absorption.

7.10.1 Vented Fillers 

To comply with the durability provisions of the NZBC, passive ventilation of metal cladding profiles at the eave is necessary for the removal of condensation or moisture.
Perforated metal or mesh closures can be used . Alternatively the profile closure should be cut back and punched or notched to allow air movement ; or the closures should be omitted altogether. (see drawing 5.7.A.) In order for the breather underlay to fulfil its intended function of conveying any condensate from the roof cladding to the gutter, the closures should either be fitted in such a way that moisture can drain to the gutter unimpeded or they should be omitted.
When closures are fitted between ridging and sheeting, the ends should be butt-jointed over the profile crowns to minimize the entry of wind-blown rain and , for the same reason, ventilated ridge closures should be fitted with their openings uppermost.

Closures should be set back by a minimum of 50 mm to discourage attention from birds, although the ingress of birds can also be prevented by screw fastening every rib of profiled metal cladding at the first purlin.

7.10.2 Metal Closures 

To prevent the ingress of weather, dirt, birds , etc . it is necessary to close off the ribs or corrugations of profiled sheets using scribed metal flashings. In extreme environments they can be used in with or without plastic closed cell closures to match the profile.

Proprietary soft edging is available but is only aesthetically acceptable for corrugate and low trapezoidal profiles. Where the profile height exceeds 30 mm, cutting and notching by machine or hand snips is the preferred option.

All soft and scribed edges should have clearance to avoid the retention of dirt and moisture.

Ridging and flashings edged with a soft aluminium or zinc strip seamed together, provide a means of closing the voids for Pre-coated and Zinc/Aluminium coated roof and wall cladding. 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.

An AZ coating should not touch the pan or tray of the roof sheeting because the retained moisture will promote edge corrosion.

The scribed metal edge of any flashing must have a clearance of 2 mm to 5 mm.