Insulated cathedral ceiling for a pole barn
Dear Martin Holladay,
I read your article about insulating a pole barn with great interest, and I hope you can help me figure out how to build an unvented, well-insulated cathedral ceiling in the new pole barn style barn. I used the typical pole barn style of construction with the roof trusses paired around the vertical poles, except that I’ve flanked the poles with conventionally framed 2×6 wall bays on either side of the poles making them interior posts holding up the high roof. Then, I have two shed roofs framing in below a band of clerestory windows at the high bay. (See Section) At the high bay roof, I’ve run 2×8 roof purlins continuously over the top of the trusses. (I don’t know the name of this technique) but it leaves the trusses completely exposed. I now have to insulate the unvented cathedral rafter spaces above the trusses and my plan was to uses rigid poly-iso board cut to fit in each rafter space (Stacking pancakes I believe you called it) and then a 6 mil. vapor barrier and followed by a layer of gyp bd. Roof sheathing is 5/8” OSB followed by a synthetic waterproof membrane and standing seam roofing.
Will I have problems with this assembly and if so, what would you recommend as a solution?