I recently bought a house and am looking at doing improvements and repairs, but unfortunately I don't have a lot of experience or knowledge in such things. We had a home inspector look over the place and he noted the lack of insulation on one side of the skylight shaft and provided the pictures shown here:
I wanted to pass my current plan by some people on here before proceeding…
I was planning on placing batting up against the bare wall (which already seems to have a vapour barrier there against the drywall) and then using vapour barrier sheets to hold it in place by stapling the barrier into the studs visible in the photos. I'd then tape the sheets of vapour barrier together. This is what was suggested to me at the hardware store I bought the materials from. Is it daft, good, acceptable, or something else?
Best Answer
You do not want a vapor barrier on the cold side of the insulation. Switch your plan to use an air barrier (or an open mesh, since you should have little air movement in the space) and it makes more sense. On the other hand, if you already bought the plastic, just poke it full of holes (but do not poke through to the warm-side vapor barrier.)
But - this will leave you with essentially uninsulated areas at each stud, and compressed insulation near them - particularly galling since they are "flat-ways" (1-1/2" thick.) It would be better to attach ~6" wide boards to the studs (sticking out from the wall), so you have a nearly 6" deep cavity to fill with insulation, and no compression where the plastic or mesh is attached.
Edit post-comments: You could also fill in between the flat studs with 1-1/2" rigid foam cut to fit (and/or sprayfoamed at the edges), and then sheet over the whole thing with 1-1/2 to 2" foam covering the studs (with a bit more sprayfoam sealing any joints or gaps), but your question indicates that you already purchased materials, so I don't want to send you off on a mission to spend more money if it's not really needed. But if you'd rather do that than add boards, it should work fine - especially if you can return the materials you bought.