Replies

1. 
   derekr | Apr 12, 2023 07:17am | #1

   Bumping for another day

2. Expert Member
   Akos | Apr 12, 2023 10:43am | #2

   In zone 3 you are allowed unvented roofs with diffusion vent. I think this is best solution for you.

   The vents on the bottom should be sealed up and you need to add a code min sized diffusion vent at the ridge.

   The benefit of this setup is that you can detail the roof sheathing as your air barrier which is easier to get air tight than the collar ties and floor joist intersection. You can also fully fill the rafter space with insulation.

   https://buildingscience.com/documents/guides-and-manuals/gm-2101-guide-building-conditioned-unvented-attics-and-unconditioned

   You can also keep the assembly vented but you will need a continuous vent channel from soffit to ridge and to add some vents near the ridge.

1. 
   derekr | Apr 12, 2023 10:57am | #3

   It is a continuous vent from the bottom to the ridge, this is how the plans were done by the architect, I don’t want to change that now

   Also the roof is already shingled, it’s too late to make sure the outside is air sealed

   I thought having a vented roof in zone 3 would solve most moisture problems even if I did have some air leaking from inside, is that not the case?

   I mean my grandparents house is 20 years old and not airsealed inside and they dont have moisture problems that I’m aware of

3. 
   derekr | Apr 12, 2023 04:22pm | #4

   The drywall is going to meet at the peak and touch the ridge beam, how should that be sealed? I’m wondering if there’s even enough room and the drywall on either side might not even be able to touch each other, I might take 2 small pieces up there to see if they can meet

   Is any insulation supposed to go around the ridge beam or no?

   Also my ridge beam is just tied together with a bunch of nails, if I ever did have a moisture problem
   Couldn’t all those nails just rust out and break and the ridge beam fall into the house?

   Edit: I think I’m going to put a 2x6 across on each rafter directly below the ridge beam for drywall to connect to and put insulation in between each 2x6, would something like this be ok? So I would have 2x6s and rockwool touching the bottom of the ridge beam then drywall on the 2x6s below that

1. Expert Member
   Akos | Apr 12, 2023 09:30pm | #5

   I think that bit of framing plus insulation is a good plan, the best way to go.

   Since you are building a vented assembly, make sure to add in the required vent area near the peak. Generally rule of thumb is 60% of your code required area would be in the soffits and 40% near the peak.

   A reasonably sealed roof with good venting works in any climate.

   Collar ties and floor joists are never easy to air seal. I would add blocking around all sides of them sealed with caulk. This will give you a flat surface for the drywall to sit against where you can seal it with caulk or foam. This will mean having to rip some odd angles but not a lot of extra work. Trying to air seal collar ties without this blocking is a loosing battle as the structure moves too much, any caulk between drywall and the collar tie will separate eventually.

1. 
   derekr | Apr 13, 2023 07:59am | #6

   Once the drywall is in I think I’m going to get some 3M flashing tape to seal that corner on the 2nd floor where the drywall meets the OSB subfloor, there won’t be any foot traffic or furniture in this deep corner anyway. have way too much wiring to put in block to seal in the joist itself

   Am I supposed to put insulation around the ridge beam? Or should I stop insulation right before I reach it

   Another thing is the hvac people had to run some of the duct work a few feet in the roof in order to reach the 2nd floor, the duct is insulated but I’m wondering if that will be enough in the winter time when the roof is cold and I’m running the heat

4. 
   derekr | Apr 14, 2023 08:22am | #7

   Wanted to bump this 1 more time