My home is in central Indiana -- climate zone 5. It has lasted 100 years with no insulation at all. I've removed all of the super thick and heavy 3/4" cement sheet rock on the exterior walls and found that the exterior cladding is all 1" pine boards, with a few patches and holes.
The house doesn't have any exterior wrap -- and right now it has vinyl siding over that 1" pine. I'm planning on leaving the vinyl siding on until I save enough $$ for hardi-plank, and at that time I'll add the house wrap and do a bunch of exterior sealing.
I've tallied up the exterior walls square footage and I've got ~1300 SQFT to insulate. I'm DIY.
I'm considering -
Spray 2" thick closed cell foam i.e froth-Paks, I would require about 2600 board feet of coverage. This would cost about $3000 for 4 froth pak 620s. This would give me ~R13, and 3.2 water vapor permeance.
Spray 1" thick closed cell insulation, then pack 3.5" fiberglass batts into the leftover 2.5". 1" spray foam is R6. The bats are 3.5" R11 packed to 2.5" is R9, which gives me total of R15. R11 is .22 a foot, which brings my cost down to $1700. This would give me 6.4 water vapor permeance.
glue 1" thick R4 EPS foam board insulation, leaving a 1/4" margin around edges, seal those edges with spray foam to create a vapor barrier. then pack R15. the EPS, R15 batts and several cans of spray foam would cost around $1500, total R Value would be 15.
My question is this -- I'm leaning towards option #2, but are there other options that might be more cost effective and still eliminate condensation on cold exterior wall, provide a comparable R value and water vapor permeance? I'm currently investigating using a sprayed or rolled on liquid waterproofing material, which would let me use full thickness R15 bats, but the products I've found so far would be more expensive than froth-paks. I'm also considering 6-10 mil plastic sheeting glued or taped to back of stud-bay, but I haven't figured out how to air seal the plastic to the sides of the stud bays.