Thanks Paul, I agree, this is turning into a great topic. I am an Engineer, but new to designing houses. I see your point re: real life loading vs, code loading. My 2x5's are full dimension hemlock. I do have the option of upgrading to 3x5 chestnut and oak rafters (from yet another salvaged barn I have), which I may do in light of the fact that they will be exposed and the loading issue.

This won't solve the problem of my 6x6 purlins perhaps being to slight. I suppose I should revisit that part of the structure since both you and Will keyed on it. My purlins span about 12 feet between posts, but only 7 feet between braces. The purlins run 40 feet with a bladed scarf joint dead center, mid span between the two middle bents which did show sag as it had no support. My first impression of the location of this scarf joint was that it was poorly placed. It seems it should have been placed closer to a post....

A steel plate on the back side or perhaps a length of 2x2 steel angle along the back bottom corner, overlapping he scarf joint, where not seem may be a good idea. Or I could upgrade to 7x7 purlins (which I have) and omit the scarf joints by either using a full 40'er or using 3 pieces to span between each bent. Oh, the options......

I did run the REScheck Mass Engery Code program with both R37 and R26.8 (Atlas Nail Base ACFOAM Vent-R) entered for roofing insulation and it passed both ways so I simply need to approach the building inspector and see if this is acceptible.

I am not using SIP's for the walls, but studding and using fiberglass bats.

Thanks for the info and advice guys. I do appreciate and value it.

Shaun