I have 1918 United Grain Growers catalog home, located near Saskatoon, Canada. -40c in the winter is fairly normal. The house has no insulation in the walls - zip, zero, zilch. It's built like a tank - plaster over wood lathe over 1x6 shiplap over the studs, a hollow cavity where the insulation would normally go, and some nice tight siding. But it's chilly.
The plaster and lath has been removed from the 2 exterior walls - they are stripped down to the shiplap. The original plan was to remove the shiplap, install fibreglass batts, vapor barrier, and drywall. But after trying to remove a few pieces of the shiplap, I'm (a) nervous about doing so, as it seems to provide some pretty solid structure to the walls, and (b) really reluctant to undergo this massive task - this stuff isn't coming off easily, which reassures me that it is meant to be there.
Great for my rock solid house... not so much for my gas bill.
And then I had a thought... now that it's pretty easy to drill into the wall cavity, and I know that the cavity is completely empty, what about just sealing up any gaps and blowing loose-fill cellulose insulation in?
I'd be heading to Home Depot first thing tomorrow and renting the blower, but I want someone to set my mind at ease first. The more I read, the more conflicting opinions I discover, and the more nervous I get. Blowing in cellulose would mean that I would have the following layers, from the outside in:
The words 'vapor barrier' do not appear in that list. Should they? I read that cellulose doesn't need a vapor barrier, and then I read that it does. Would it be wise to put a vapor barrier between the shiplap and the gyproc, or is that unnecessary, or is it stupid?. I live in a climate that is very cold in winter, not too bad in the summer, and the air is pretty dry most of the time. I read so many conflicting things from so many parts of the world that I don't know how to tell what is right for my house and climate!
Thanks so much for setting my mind at ease... :)