Incredible Cross Gable Roof Addition Ideas. Web i have just calculated a very very rough calc for the ridge beam spanning from post on dashed line to existing roof ridge junction: Tying a roof perpendicular to the existing roof will be another matter.

Web the average cost to install a gable roof is about $9,000 (installing standard architectural shingles on a 1,500 sq.ft. When designing a home, one of the most important. A box gable roof has a triangular extension at each end of the house,.