This summer I will be re-siding and renovating the exterior walls of my house. I have a background in construction and homebuilding and I'm not new to any of this but I've got a question that I can't find a good answer to.I'll be stripping the siding, buffalo board, and R11 insulation from the walls. The intent was to replace with R15 3.5" batts and then polyiso board over the top to insulate studs and restore thickness of the existing buffalo board sheathing.But, if I rip out that insulation plus the kraft facing, i'll have no interior vapor barrier (yes I know kraft paper is crap vapor barrier anyway, but it's better than nothing) - and I live in a cold place where I need it to keep walls from rotting from the inside out.Is there an established method to deal with this? Or is it best to just pull the old insulation out and leave the kraft facing behind (they separate easily enough) and then use unfaced in the walls?My other option would be to pull it all out, spray foam a 1 inch layer, and then use new R11 compressed to 2.5 inches (which would be ok in this case because the sprayed closed cell is R 6.5 per inch.) and then polyiso board on the outside like planned. But this is REALLY expensive compared to leaving the kraft facing behind.Thoughts? via /r/DIY http://bit.ly/2SbealR
