Foam sheathing & spray foam
I am an engineer working on a set of plans for a new house for me & my family.
The structure will be located in the Northern edge of Zone 4A.
I originally wanted to use SIP’s for the walls of the house; however, the cost to benefit ratio is just not there. So, I started researching other building techniques that I could incorporate into this project. I see the benefits of airtight construction and I really like the benefits of spray foam insulation. These “newer” techniques are not readily used in my area; therefore, I do not have a lot of hands on experience with them. I live in a “16” o/c with Batt Insulation is the only way to build a house” area.
Proposed Wall Construction:
~ 2″ x 4″ Wood Studs @ 24″ o/c. Hardie Plank Lap Siding will be used for the exterior finish.
~ The interior finish will be 1/2″ airtight drywall.
~ As currently designed, sheathing is not required for racking strength.
~ The project is located in an area of rural Southern Indiana that essentially has no applicable residential building codes.
Here is my question…
If I sheath the house with 1″ (R-5) Extruded Polystyrene (taped and caulked), would it be in anyway beneficial use 1/2″ or 1″ of Open Cell Spray Foam or should I just use R-13 Batt Insulation?
I can purchase the Extruded Polystyrene for the same price as 1/2″ OSB. Since I have to install some sort of sheathing for the spray foam, why not get a little extra insulation of the same price?
Most of the exterior stud walls are basically curtain walls. Is there another, construction technique that you might recommend for these curtain walls?
Thank you in advance for reviewing my question. Any and all replies are greatly appreciated.
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