A roof fall was found on the South Mains ""D"" mainline belt at 28 x-cut. Fall was approx. 30' long by 26' wide by 7 to 8' high. Fall did not obstruct ventilation or escapeways. Area bolted with 8' Install III bolts with resin assisted with supplemental support consisting of bacon straps, wood cribs and 4"" H-beams. Cause of this fall was weathering of the roof.