Replies

1. GBA Editor
   Kiley Jacques | Nov 03, 2021 03:14pm | #1

   I’m giving your question a bump. While you wait for experts to weigh in, consider these words: “Unvented roofs in the snow belt may still need some type of venting to keep the roof cold and prevent ice dams.”

2. 
   ktoblesky | Nov 03, 2021 03:19pm | #2

   Thanks Kiley. I appreciate it.

3. 
   rszimm | Nov 03, 2021 06:50pm | #3

   Are the rafter bays enclosed? (Ie, do you have a ceiling over the deck, or exposed rafters). If exposed, I’d say certainly not. If enclosed I’d also likely say you don’t need it, but it gets a bit more iffy. You want to keep the whole assembly the same temperature. Exposed bays makes this easy. An enclosed bay has the potential to have a temperature gradient that would cause condensation. Honestly though this seems a bit theoretical. I do not believe IRC requires it.

1. 
   ktoblesky | Nov 04, 2021 10:35am | #4

   Thanks for the response. Yes the rafters do have a ceiling so the bays are enclosed.
   Ken

4. 
   Jon_R | Nov 04, 2021 11:28am | #5

   IRC R806.5 should be for "above conditioned space". But I don't see where it says that. It gets even trickier if the space is occasionally conditioned.

   I've seen some moisture problems in/above unconditioned spaces, but never in a dry place like Reno.