This is an
interesting roof location, where parapet flashing shall create a transition with
adjacent wall, which right side extends down creating convex corner and the left
side stands on the roof.
The water running
on the wall would enter below the waterproofing EPDM membrane and show up the
interior. Any standing melting snow would also cause leaks.
The basic
difficulty of this condition is to produce a workable flashing transition, which
would create a "step", joining the cap flashing on the left and covering a
convex corner on the other side.
The metal panels
are restless and very volatile thermally and the design is very challenging.