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Discussion Starter #1 (Edited)
I'm planning to insulate the ext. walls in my old house and the house is framed with 16'' oc 2x4s, tell me if you think this plan would work.

Flash spf wall cavities for air sealing using home kit
attach 1"-1.5" polyisocyanurate to the studs using plasti-cap nails or screws
blow in cellulose insulation behind the foam board
tuck tape foam board joints
attach 1x furring strips vertically at 16" oc
1/2" drywall
cold climate
 

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Discussion Starter #3
can i use batts after the 1 inch of cc spf ill only have 2.5 inches of the cavity left before i put the foam board up. its a big house and i want it tight and insulated, very cold winters here and strong winds. open cell spf i dont know is that as expensive as the cc??
 

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What is the finish siding?

Any plywood, OSB?

Gary
 

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can i use batts after the 1 inch of cc spf ill only have 2.5 inches of the cavity left before i put the foam board up. its a big house and i want it tight and insulated, very cold winters here and strong winds. open cell spf i dont know is that as expensive as the cc??
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Not a good idea for R-value loss: https://docs.google.com/viewer?a=v&q=cache:9cHjO3GGTK8J:www.flashandfoil.com/pdf/Foam-with-compressed-batt.pdf+calculate+density+of+fiberglass+insulation&hl=en&gl=us&pid=bl&srcid=ADGEESi9inBNwvuWT1TTgEzcKee83u0__Fc4Gd792pEcUfXiM5SidZDcGUi6EelMRUVSE3YYZj1aHl81iNb41vIz1MOfjMVkK3LTYT6fw-IlJFPQM-WjXnCiwlw0At9laUeqBHI8Yels&sig=AHIEtbQuKByI2A4iCXbOSFjptmqEXxrdKQ

With all the foam board in the cavity, the first condensing surface will be inside the f.b., though you will still get a whole-wall thermal loss due to the conducting studs (thermal bridging). This leaves the exterior sheathing colder without the house heat going through the cavity to prevent mold with an exterior water leak or moisture wicking from the stucco (moisture reservoir).

Where are you located?

Gary
 
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