Recommendations for Easy, Budget-Friendly Exterior Insulation
We’re planning to add insulation and new siding to our 100 year old zone 6 home next summer. We’re in Montana and its quite dry here.
The exterior walls are old dimensional 2×4 with a mix of drywall and lath and plaster inside. Some of the wall cavities have blown-in cellulose and I imagine some of bays have little to no insulation. I’ve pulled off a few areas of exterior siding and it looks like there is shiplap over the studs.
I’d like to add insulation to the exterior. I’ve been considering simply fastening zip r panels over the shiplap. IRC 702.7.1 suggests that R7.5 would suffice given my wall thickness. With zip’s r panels this would suggest that a 2inch (R9) panel would be appropriate. I’d then be putting hardiboard over the top of the zip-panels. Any concerns on this configuration?
Any other suggestions for a better insulation spec given my wall depth etc? Budget and ease of install take priority. I am open open to foam board and can make up for the negative impact on other aspects of the project.
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