Replies

1. GBA Editor
   Martin Holladay | Jul 13, 2015 06:35am | #1

   Danila,
   You're going to have to remove the existing cellulose, at least temporarily. If the cellulose is clean, it can later be re-installed.

   The best way to proceed (once the cellulose is removed) is to carefully remove the bead-board ceiling from below with a flat bar. Then install a drywall ceiling, tape the drywall, and re-install the beadboard.

   Once that's done, you can insulate from above -- either with the cellulose you temporarily removed, or with new cellulose.

2. 
   diznila | Jul 13, 2015 03:38pm | #2

   Thanks Martin.

   That's somewhat disappointing but understandable. There's really no good way to take the ceiling down, it is fragile enough in places that it would likely just splinter and much of it would be un-useable.

   Would something like drywall on the top of the attic joists perform a similar function? Particularly if the cellulose was removed, and there was just an air gap between the beadboard and drywall?

3. GBA Editor
   Martin Holladay | Jul 13, 2015 03:46pm | #3

   Danila,
   If you are unable to temporarily remove the ceiling boards, and you have your heart set on keeping the existing boards, you could remove the cellulose; protect the back of the boards (facing the attic) with strips of cardboard laid between the joists; and then install spray polyurethane foam onto the cardboard from the attic side of the ceiling.

   One or two inches of spray foam would provide an air barrier. Then you could complete the insulation job with a thick layer of cellulose.

4. Expert Member
   Dana Dorsett | Jul 13, 2015 05:08pm | #4

   The cardboard itself would be a sufficient air-barrier, as long as you sealed the edges to the joists with can-foam.

   Another approach would be to use a broad-sheet housewrap and NOT cut it, but rather, to wrap the joists with it, stapling it to the sides of the joists down near the bead-board level, sealing it at the edges, and over lapping any adjacent sheets where they can be adequately taped & stapled to framing, and installing the insualtion over the result. With 8-12' wide sheets there will be far less seam leakage etc. .

   But if there are lot of nail-points sticking out that would tear a sheet-goods approach, a couple inches of open cell spray foam does wonders as an air seal. You'll still want the cardboard above the bead board to keep the spray foam from sticking to the bead board, which would make any repair/replacement of bead board more difficult in the future.

5. 
   diznila | Jul 13, 2015 11:48pm | #5

   Thanks for the advice, Dana and Martin.

   I will peel back the cellulose and see how it looks. I am somewhat nervous about wide area spray foam because of losing the ability to change something later (and off-gassing concerns). But put over cardboard, it could be a great solution here, and off-gassing shouldn't be an issue in the attic.

   Cool, I've got some work to do!

6. 
   diznila | Apr 05, 2016 07:49am | #6

   Just wanted to follow up on this old thread for anyone seeing it in the future. I ended up removing the old cellulose, and using rolls of cardboard padding between the joists. For the most part it was a great fit - I found 24" rolls that fit (most of) my joists.

   Then I had a contractor spray on a flash coating on spray foam, and then topped it off with more cellulose. So far, it has been working great!

7. GBA Editor
   Martin Holladay | Apr 05, 2016 12:13pm | #7

   Danila,
   Thanks for sharing your success story. I'm glad the job went smoothly.