I have installed b-vent flashing on my roof which is at at 9/12 slope. I sank nails along the left, right, and top edges that are under the shingles. However, I'm debating if I want to attach the bottom edge. Whether I use gasket screws or nails, I feel it's just making a few additional holes that could potentially leak and that aren't very necessary. The flashing seems sturdily affixed without them and I don't really think water is going to back upwards. I've seen both attached and unattached b-vent flashing. Could I have suggestions as to which is better and why?
I am a firm believer of not nailing the exposed parts of flashing.
I do add roofing tar or other sealant under the flashing.
Normally if the roof slope is 3/12 or greater there is little chance of rain getting under the flashing. Wind driven rain could be an issue, but if sealed properly it is normally minimal or nil.