Unintentional roof fall occurred in 4-Right (001) Section while mine was idle. Fall found by pre-shift examiner at approximately 8:45 PM - called outside at 9:05 PM. Fall from x-cut R-2 entry to L-1 entry (175 feet x 19 feet x at least 8 feet in height). Area supported with 4-foot fully grouted bolts, except belt entry supported with 6-foot super-twist & T-5 Channel.