what caused trusses to crack (see attached pics)? Poor ventilation in attic and widespread mold growth. 2x4 trusses at 24". 5:12 pitch standard construction. Do you think high humidity/poor ventilation could weaken wood enough to crack it? or was it weight of ice and snow? wavy sheathing observed from top of roof surface. to me, all is pointing toward origin of cracks and dipping of top chords/sheathing to poor ventilation. No h-clips observed to attach sheathing.