Clearances and Minimum Slope

E2/AS1 requires 35 mm clearance between wall cladding ends and aprons or decks, and 5mm clearance between wall cladding ends and inter-storey junctions or window head flashings, which must have a 15° slope.

In practice, the 35 mm clearance stipulation is not necessary for weathertightness or durability when the wall cladding ends are unlikely to suffer build-up on debris, which is particularly relevant where wall cladding ends above a sloping apron or a surface that is easily accessed for maintenance. In such cases, a clearance of 20 mm is sufficient to prevent contamination and prolonged wetness of the cladding.

The 5 mm clearance to inter-storey junctions and window heads is not achievable when the horizontal flashing has a slope of 15°. The clearance at the back of the flashing/roof pan should be minimal, 2 – 5 mm, and the slope of the flashing should be decreased to minimise the clearance at the rib crest. For vermin proofing, the maximum clearance at the rib should be 8 mm.

A printable bulletin is available at: BC01 Clearance between sheet ends and transverse flashings.

Extract:
"The Metal Roofing and Wall Cladding Code of Practice (COP) stipulates clearance should be provided
between the bottom edge of a profiled sheet and a transverse flashing, such as a change of pitch
flashing. The purpose of such clearance is to prevent the end of the profiled sheet from damaging the
protective coating on the flashing, due to movement of the former from thermal expansion..."