Widows Walk | Flat Roof Before and After by Flat Roofs by Pegram | Dec 3, 2014 | Flat Roof Repair, Flat Roof Systems, Flat Roofs By Pegram, Residential Roofing | 0 comments Goodbye tar and gravel flat roof. Hello TPO Membrane energy efficient flat roof! Ain’t it purdy?! BEFORE | This flat roof had been repaired over the years with tar and gravel but that never stopped the leaks from damaging the porch and railing. AFTER | Totally sealed membrane roof system will last for years and finally make the porch and railing water tight.