I have recently obtained an owner builder permit for an addition to a roughly 1000 square foot 1940 built house out in Reno NV (Climate zone 5). I am adding 1000 sq. feet of living space (2 stories) to the house and have run into a roof framing detail problem. The ceilings in the existing home are all exposed heavy timber rafters with T&G planks (see picture) and I was hoping to continue the trend into the new portion of the building. Plans have been drawn up for 4×6 timbers with 1×6 planks. The architect is calling for R38 on the roof. I would like to see R50. Here begins the problem.
Assuming I stick with the current engineering plans (picture 2 and 3) I don’t see a way around a 10 inch thick roof using poly-iso. Does this need to go back to the engineer for a 2×10 so I can insulate between rafters. Assuming it doesn’t and I can make a real thick iso roof I’m looking for recommendations on roof details.
Thanks for considering the problem, and please note I’m pretty new to the world of construction. I’ve got a positive attitude, but not a lot of knowledge.
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