Ell flashing should be nailed every six inches on center. On a Bonita Sprints roof I found the ell flashing uplifted. Not enough fasteners were used and the sealant has deteriorated. We suggest sealing the underside of the ell flashing and installing the correct number of fasteners as specified by code. Another layer of membrane or shingle should be installed to cover the ell-flashing flange and provide a more aesthetically pleasing transition area.