0

I am planning to add additional blown-in insulation to my attic space. Currently there is about 5" of old cellulose insulation. I plan on raising this to around 15" to achieve a rating of R50. I will no longer be able to see the joists after adding this additional insulation. I am aware of this being an issue for moving around in attic. My question is, should I keep the insulation contained to each space between joists (rafter bay, if that's what you call it)? I could use netting, plywood or foam board if need be.

2
  • If you use plywood to build up the sides of the joists to contain the insulation, then you still won't be able to walk across them.
    – SteveSh
    Dec 9, 2023 at 15:24
  • Heh, good point @SteveSh. The barriers could become somewhat of an annoyance or hazard.
    – qq4
    Dec 9, 2023 at 17:00

1 Answer 1

4

No. Covering the joists improves your overall insulation, since wood is not a particularly good insulator, and netting/barriers/etc will just make it even harder to move around.

Just bury the joists. If there are places you need to go on a regular basis, screw down catwalk boards. If you go there a LOT, make an elevated catwalk.

Otherwise, take a snow shovel with you and wear a dust mask for the rare things where you need to get somewhere to run a cable or check a leak or whatever. Rake the insulation you shovel aside back in place when the task is done.

4
  • I think blown in insulation is a PITA just for the reasons you mentioned. It's a lot easier to move a fiberglass batt or roll out of the way, then put it back.
    – SteveSh
    Dec 9, 2023 at 15:26
  • Yeah, I would sister some taller joists (doesn't need to be full length, and doesn't need to be flush with bottom of existing joists--can be vertically offset) anywhere you plan to walk, and put a catwalk after blowing in the insulation.
    – Huesmann
    Dec 9, 2023 at 20:35
  • @Huesmann, crossframing (with blocking in every other opening) would be significantly cheaper and easier than sistering.
    – popham
    Dec 9, 2023 at 20:51
  • @SteveSh given how rarely one needs to go, and how much better a job of blocking air leaks cellulose does than batts, I don't consider a little snow shovel / rake relocation of cellulose a big deal. And it doesn't make me itch.
    – Ecnerwal
    Dec 9, 2023 at 22:33

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.