Two Vapor Barriers on Roof of Cottage Remodel
New to the forum but long-time Fine Homebuilding subscriber…
I recently completely renovated our “cottage” up on the hill to turn it into a nice woodworking shop and my office in the upstairs. I will be there every day, all day, so it needed to be nice and comfortable.
I live in a far northern climate where winters can be very cold and long.
Unfortunately, I am asking this question after the fact, but here is the deal. I put Titanium UDL on the roof without understanding much about its permeance and what that means. I think put horizontal purlins on top of that and my steel roof on top of the purlins. The purlins were necessary since the roof is a 12/12 and very challenging to work on without.
Underneath that Titanium is the 1/2″ sheathing that the previous builders had installed (40 years old). That is another reason for the purlins (to add a little extra strength).
Inside of the sheathing is open-cell Icynene spray foam. It is 5.5″ thick in the rafter except when it passes above the collar ties and below the knee walls, they went thicker there. Then, everywhere it is only 5.5″, we wrapped it with 2 inch rigid foam and filled the gaps with expandable. Behind the knee walls and above the collar ties it was then “painted” with a vapor barrier paint.
This building should be pretty tight now, but should I be worried about having the rigid foam and painted open-cell foam as a vapor barrier on the inside and the Titanium on the outside? Am I going to rot my sheathing and rafters? Is there anything I can do?
Thank you very much!
P.S. Let me know if anyone prefers to see images to help understand what was done.