What is the best exterior Wall and Roof Rigid Insulation for a barn renovation?

Ron Busch
Updated: Sept. 15, 2020

Building a 24 X 50 Post and Beam barn.  Thinking of applying 2 layers of 4 " (8" total) of rigid insulaton, offset seams on top of 1 X 8 sheathing.  Seams of top layer would be taped / sealed.  Layer of Roofing Paper / Water screen followed by 2 X 4's for strapping using 10" RSS type screws through to the sheathing and purlins.  Facia Board installed prior to insulation being emplaced with roofing paper / water screen wrapped about 1/2 over the top of the facia board.  Metal roof attached to strapping.

Walls much the same but w/ one layer of 4" rigid insulation.  1/4 " Plywood sheathing attached to the Girts, Rigid Insualtion, rain screen (Tyvek?) 2 X 4 or 1 X 4 Strapping screwed through the insulation to the Girts.  1 X 10 Board and Batten siding.

Barn will be fitted for Radiant Floor Heat ( haven't decided yet on heating source) Slab will have 4" of Rigid Insulation under the slab and extending 4' out from the edges. I believe I am located in Climate Zone 6.  Does the above make sense? 

Will the 4" on the exterior of the walls suffice? 

I do not wish to place insulation inside the barn as I wish to maintain the asthetic of the bones of the barn being fully exposed and seen from inside.


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