I have an old concrete garage roof that is leaking. I plan to attach a layer of pressure treated wood then glue an EPDM sheet to the surface.

I understand how to install a drip edge on the sides however, I'm not sure what to do where the flat portion abuts a short arched piece. Images below. I'd rather not cut it off or attempt to refinish it to a taller edge at this time if possible.

Is it totally insane to just fill the corner with caulk or other adhesive? What would a professional do?

Back sketch of the garage Sketch Roof

  • "Is it totally insane" That would be Insane in the membrane ?
    – Alaska Man
    Commented Aug 2, 2020 at 19:39

1 Answer 1


I would run your EDPM sheet right up the back side of that arch and onto the top surface using the same adhesive you use to hold it down to the flat surface. I'd pull the membrane about 1/2 way across the horizontal top of the arch. Then I'd use the same flashing you're going to use for the sides to flash over the vertical edge of the arch.

Note: I'm not a roofer, this is just me "thinking logically", so wait for some confirmation before doing this.

Also, I'd suggest that while it might look nice, the wooden planter isn't doing your roof leaks any good, and it will most definitely not be good for the rubber membrane you're about to lay down.

  • I haven’t had an arch but a raised section that I ran the membrane rain up the wall a few inches attached it and sealed it I think going up and 1/2 way on the wall would have less chance of leaking with minimal cost.
    – Ed Beal
    Commented Aug 3, 2020 at 19:36

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