Exterior renovation and additional insulation
Am re-siding my carriage home/wood shop after a brutal wind and hail storm did my pine board and batten siding in last summer. Planning on taping osb seams and adding eps foam or roxul. The conventional 2×6 walls have a 6 mil vapour barrier, from what I’m reading it seems like any osb sheathed wall should use a smart vapour barrier, especially since I’m taping seams. I don’t plan on removing drywall to change the vapour barrier. What are my options? Will the roxul offer enough permeability, or will the osb that trap moisture in the wall. Heat source is electric boiler supplemented with wood heat, and plans of adding a solar thermal system, so I’d like to get the building as efficient as possible without tearing out the drywall to replace vapour barrier.
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I'm in zone 5 here and code has been R5+2x6+poly for a long time. These walls works just fine. Taping the seams actually improves the durability of the wall as you reduce air leakage which is typically the biggest source of moisture in walls. Make sure to get your window and door flashing details right as well while you are redoing the siding.
You want to improve the robustness of the wall, go for a permeable foam (unfaced EPS/GPS or permeable polyiso). Mineral wool is a great option but it is spendy and a bit annoying to work with as it is still squishy so it is hard to get strapping flat.