Where to create thermal envelope in attic while using open-cell foam in rafters?
I am having foam put into my attic and turning it into an unvented attic space this week. My home has a slightly odd envelope situation where I have an adjoining 1 car garage that is having its attic space foamed, but the roofline for that attic also slightly extends over to cover an entrance hall and laundry room of my house. The foaming company wants to seal off that attic so that it does not communicate with the rest of the house, but that would put that hall and laundry room into that area while the rest of the house is below the “other” sealed attic. That laundry and hall does have insulation above it, but I was under the impression that I *want* the house to communicate with the attic once the attic is sealed.
Is there a correct either/or answer as to whether to allow these two attics to communicate?
I suppose I could have them rig up some studs where the hall and laundry room stop and create a thermal wall in that spot so that only the attic above the single car garage is on its own.
I *do* have plans at some point to install a mini split for that garage and condition it and the above attic, but as I do not know the costs yet, I have no idea how far down the line that would be done.
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