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I have long scraps of plywood (1/2 in and 3/4” thick) left over from a recent renovation and since they are my retirement plan, due to price paid,I don’t want to toss them and don't really have a good place for storage either.

One idea I had was to screw them over attic space joists (with blown in insulation) so that I have a stable platform I can walk on whenever I need to get to space for various wiring or other jobs. Would this go against any code (KY USA), or is otherwise a bad idea? This will be temporary 6-8 screws per board to keep them stable enough.

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    It will probably reduce your insulating where you put them assuming the insulation is over the joists.
    – Gil
    Jun 26 at 1:54
  • Why would it? I’m nit removing insulation just adding to it in top
    – David
    Jun 26 at 2:14
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    Found this: but don't take this as gospel. up.codes/viewer/kentucky/iecc-2009/chapter/4/… , and understand Gil is right that it will reduce insulation (R) factor if you have to compress the insulation to lay the plywood on the joists, because it's the air space in the thickness of the insulation that matters the most. Jun 26 at 4:09
  • @g-warner I understand, the insulation is actually at the joist surface level, so there will be. There will be no compression, so unless there is some physics I don’t understand, the thin plywood would actually add a negligible R value. Won’t it?
    – David
    Jun 26 at 17:06
  • Yes I looked at some data. And it is negligible. Jun 26 at 18:14
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There is no code about adding flooring or walkways to your attic.

But rules to remember.

1 Don't change any of the framing

You cannot cut or move any of the framing for the roofing or the deck. Cannot make cuts or alter to make the storage/walkway space bigger (unless those changes are signed off by engineer + inspector)

2 Don't jam the flooring in

Remember that this is not a conditioned space. If you are using plywood and a sheet barely fits... Well when the attic gets 130 degrees in the summer all of that wood is expanding. Wood expanding can move framing and loosen braces (seen both happen). Just give yourself a gap - 1/4-1/2" between framing and pieces.

3 Understand the insulation factor

There are kits that you can buy for attic flooring that basically raises the ceiling joists. These are designed because most attics require about 16" (I do 24" because cost is negligible once you get that far). Well if you just squash blown in insulation it will be about 8-10" high in most houses so it will run short. I would either rollout some fiberglass double layered under or just add blown in over your walkways.

4 Try to mark the walkways

We use flag sticks to mark walkways in attics with insulation. I have seen ribbons on framing and other stuff. Remember that yea you know what you put down but it might be a year or two before you use it.

5 Flooring ends on joists

Might seem just basic common sense... but I have been in attics and step on a piece of plywood flexing and quickly realizing nothing was below it except my foot almost going through the ceiling.

  • There is no code against it and nothing you need the inspector out on.
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    Thumbs up on trimming your floorboards so they don't end between joists! Doesn't matter how temporary, even if it's only for an hour! :-(
    – jay613
    Jun 26 at 10:31
  • Be sure to anchor everything to the joists because movement or flex and the edge of that plywood will slip off the joist. Even for temporary (1 month to 1 hour) consider H-clips besides countersunk (drywall?) screws. i.stack.imgur.com/JOCPm.jpg Jun 26 at 18:16

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