2×4 walls, R-13 Kraft, Zip R-9, probably metal or Hardi siding?
Zone 6A. 2×4 walls of older home. No poly or anything of that nature.
The company I hired is owned by a local guy, I found out the hard way he has a history of quitting mid work and defrauding people. So my home is currently protected by just zip sheathing, 2 walls still with original siding . My plans of exterior eps & rainscreen were ruined. No other company here will do exterior insulation.
One reputable company will tear out and rebuild with Zip R and that’s my only option for additional insulation. (Even reputable companies think I’m talking witchcraft when I ask about air sealing foundation to sill and etc 🙄 so I’ll finish the airsealing personally) I have two options 1: reside oldschool way without any exterior insulation. 2: resheath with Zip R9 then side with a metal siding or hardi plank. No furred out rainscreen as that’s witchcraft too. And hiring on helpers or friends to do my own exterior insulation before the company resides isnt feasible either.Â
I’m torn because there is such disagreement about Zip R in cold climates and mold concerns. And I’m going to assume the Zip R wouldnt be installed picture perfect? Maybe it would be safer for me to reside oldschool and then do something on the interior instead like foam board over my studs and then drywall? (Hate to lose the space & do all that work personally but I would.)Â
I’m living here forever and then my daughter will own this home, so I’m not concerned about resale values- I’m concerned about upgrading for comfort & lower heating Bill’s.Â
1: oldschool- siding on sheathing.
2: Zip R9 sheathing and siding.
3: oldschool- s on s/ interior insulation work of what kind, I dont know- any suggestions?
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If it helps, I'm in zone5 and 2x6 walls with R6 ZipR are pretty common here. They are built with interior vapor barrier though.
In your case with a 2x4 wall, the R9 ZipR is sufficient for condensation control. I would have no qualms about building with it even without an interior vapor barrier.
The one thing to watch for is the frames have their guns set correctly when nailing up the ZipR. Unlike with regular sheathing, it is easy to overdrive the nails reducing the sheer strength of the wall.
Taped seams is the easiest for the installer, just make sure they (even better, you, after hours) roll all of them for proper adhesion.
Zip R9 taped would be fine over 2x4 framing for zone 6A. That would be in line with Building Science Corp recommendations for "hybrid assemblies" -- at least 35% of your thermal resistance is outboard of the first condensing surface. You could even upgrade your batts to R15 mineral wool and be fine. The outboard Zip R9 route will perform much better than trying to install interior foam and attempting continuity and airtightness at outlets, intersecting walls, etc.
Suggestion on the rainscreen if you really want it--you can use sill sealer (foam roll) spaced 16"ish and stapled up to give you a small gap, then fold and staple insect screening at the siding base and window heads. Contractors might stomach that better than the fuss of 3/4 furring. A small gap is better than no gap.
For rain screen you could probably talk them into a product like Slicker from Benjamin Obdyke. It’s pretty easy to install.