I have a 50 year old concrete block building measuring 50 ft x 26 ft that has a flat roof. The building has settled and the roof no longer pitches correctly to drain locations. Water sits in puddles and the roof leaks in many locations. How do I most economically repitch the roof properly and seal leaks. I may need to add 4-8 inches in pitch. The current roof construction is metal girder joists, ribbed sheet metal deck, and a rubber membrane that is 10+ years old.
Thank you for input.