I have a gable vented attic and simply got a brand-new roof.
My house is a cape cod from 1937.
Been studying your structure science posts for practically 2 years to just get whatever right.
I understand the appropriate approach would have been to have a soffit and ridge vent.
Im in environment zone 4a.
I got a brand-new OFFICE shed dormer that is venting into the attic gable vented primary roofing system line.
On the outside we included 3/4 ″ insulation and brand-new siding.
However my contractor stopped working to adhere Z-tape sheathing seams externally.
I want to insulate these walls as much as possible. R15 or even much better R21 without SPF.
However also comprehend the wall still needs to breathe.
For the 2 × 4 framing for walls:
If I use
ZIP System Flashing Tape to the INTERIOR sheathing’s joints/ spaces
SPF interior cavity picture boundary frame
SPF top plate and bottom plate
then Rockwool (or Cellulose dense pack wall cavities)
then can I add a constant layer of 1-2 ″ of stiff foam board over the whole wall to avoid thermal bridging? (ie so studs are not visual any longer) Please see confined Pic 1
and after that add 1/2 ″ drywall over the “unfaced (should it be unfaced?)” foam board?
Would this be excessive rigid insulation in addition to the 3/4 ″ insulation under the brand-new siding?
Does this still enable the walls to breathe?
Likewise do I require to apply some furring strips to the stiff foam board so that the drywall can be adhered?
Question # 2
:
I added 2 unvented smaller gable dormers (2 × 8) in the Restroom and MBR.
They are also NOT venting into the primary roof line, as they are now cathedral ceilings.
If I use closed spray foam directly to the underside of the unvented sheathing for the 2 dormers is that appropriate?
Or should I install baffles or rigid foam board to the sheathing and after that apply the closed SPF to the baffles?
(To get to R-49 for an unvented cathedral dormer roofing.)
Question # 3
: (Walk-in Closet) ( Photo # 2)
I got a brand-new Walk-in Closet shed dormer that is venting attic gable vented primary roofing system line.
On the outside we added 3/4 ″ insulation and brand-new siding.
In the enclosed photo you can see that the bottom part of the Walk-in Closet is a kneewall which goes up about 1 foot. I intend on sprayfoaming that part of the roofing slope with SPF.
Then for the remainder 2 × 4 framing above it my plan is to either use Rockwool or Cellulose
ZIP System Flashing Tape to the INTERIOR sheathing’s joints/ spaces
SPF interior cavity photo perimeter frame
SPF leading plate and bottom plate
then Cellulose dense pack wall cavities (or Rockwool)
then can I include 1-2 ″ of “unfaced” (??) stiff foam board over the entire wall (ie so studs are not visual anymore)
and then add 1/2 ″ drywall over the “unfaced (?)” foam board.
Does the combination of the SPF on the roofing sheating (for kneewall listed below the 2 × 4’s walk in closet wall) work in combination with the Rockwool and additional outlined steps discussed in the above paragraph?
Any help is most appreciated.