Flashing Cover
The weathertightness of a flashing is determined by the flashing cover (C), not the flashing dimension.(D) Other considerations are catchment area, wind exposure, roof pitch and profile height.
The minimum flashing cover (C) must correlate with the tables below.
There are three categories of exposure or pitch that determine the required flashing cover .
Category A:
- Low, Medium or High Wind Zones, all pitches
- Very High and Extra High Wind Zones where the pitch is equal to or greater than 10°.
Category B:
- Very High where the pitch is less than 8°, and
- Extra High Wind Zones all pitches.
Category C:
- SED Wind Zones up to 60 m/s all pitches.
NOTE: These tables are relevant to trapezoidal profiles with a rib height of 25 – 34 mm and standard corrugate. Longitudinal Apron flashings over profiles with a rib height greater than 34 mm may have one rib overlap
|
| Category |
|
|---|---|---|---|
| C2 | 1 rib | 2 ribs* | 2 ribs |
| C1 (smooth surface) | 50 mm + hem or 75 mm | 75 mm + hem or 100 mm | 100 mm + hem or 125 mm |
| C1 (profiled surface) | 75 mm + hem or 100 mm | 100 mm + hem or 125 mm | 125 mm |
*Not to exceed 300 mm. Two ribs cover can consist of two machined crests or one machined crest plus an upstand, hand-formed from the adjacent pan.
/cop/flashings/flashing-cover
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