I have seen it recommended to us roofing felt under strip flooring, does that also apply to using it under plywood. I am replacing the damaged finised flooring in a kitchen of a 60 year old house that has diagonal subfloor. I am putting linoleum on the plywood.
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the plywood should be glued and screwed to the joists, so you would not want tar paper there.
"Put your creed in your deed." Emerson
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
The plywood should underlayment grade. That means that the cores should ber plugged so chairs,etc won't go through the surface.
When you are putting ply over diag. 1X subfloor, there is generally no need to glue it down. The only reason you would use felt is if you have a need for a moisture barrier -- probably not. I usually put 2 or 3 screws through each diag. 1X into the joist to tighten them up and eliminate chances for squeaking. Then I try to hit the joists every foot in the field of the ply and every 6 inches on the edges with longer screws. I try to line up the edges as much as possible with the joists, and stagger the cross joints. I like the deck screws from HD ("DeckMate", or something like that) because, for me, they go in with fewer busted screws or stripped-out heads. Takes a ton of screws.
I'd recommend you use 1/2" minimum ply. Stay away from the big box ply -- I've had awful luck getting ply there that they must have forgotten to glue up the plys -- delaminates like crazy. As another poster mentioned, make sure you get a good grade of ply with no voids in the core. Countersink the screws a bit and fill them and level the joints with a good leveling product, or you'll be able to see them through the linoleum.
Mike Hennessy
Pittsburgh, PA
I got the impression that he is removing bad diagonal 1x material and replacing it with ply. Not adding ply on top of the 1x."Put your creed in your deed." Emerson
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
Dunno -- maybe he'll clarify, but the OP said "replacing finish floor", not sub. Anyhoo, if he is replacing the sub (are you listening, OP?), he'll have some extra issues to deal with since the diag usually goes under the walls and bottom plate. If it was me, I'd do all I could to keep the diag and cover it.
Mike HennessyPittsburgh, PA
I am not replacing the diagaonal 1X just putting the ply over it to make a good surface. Also am planning to use the tongue and grove ply. Thanks much for the recommendations.