What's the proper detail to apply membrane or tar paper to an inside roofing corner, where a sloped roof meets a higher wall at a corner? Of course a metal flashing goes on top of of the membrane, and the wall's WRB must lap into the metal flashing. But here I'm asking about how to lay out the details of the bottom-most redundant water shedding layer.
Tar Paper or Membrane underneath, I've never found a single drop make it through metal flashing...that was replaced or re-faced with every new roof. If we're not talking about the slope being parallel with the wall & the slope is perpendicular throwing water at the wall, then definitely membrane as far & wide as you can under very tall & wide metal flashing.