Hello. I have two rafters in a log cabin structure that are fractured near the ridge. The two affected rafters oppose each other. The rafters are not water-stained and fractures are not in areas of knots. The rafters span about 17 feet on a 12:12 pitch roof. The rafters are about 3 wide, 7 1/2 inches deep and spaced about 6 feet 5 inches apart. One exterior wall (in near alignment with rafters) has wood rot near its bottom where a deck was once erected (and inadequately flashed) adjacent to the exterior wall. Please see photos attached and let me know what you think caused the rafter cracks. Thanks.