I am replacing a corner tub with a solid surface shower pan, and the flooring under the tub is 2×6 t/g car decking over beams on 4 ft centers. The car decking, if you step on it, flexes too much for the new pan to sit on. If you bounce on one foot on one board, you can see and feel it move, prbly 1/4″ or so. I was thinking of applying a 1/2″ plywood layer on top and 3/4″ ply beneath, glued and screwed to make a plywood sandwich out of the 2×6’s. I’d go 3/4″ on top, but we are going to set the new pan in the hole the old tub came out of, and the rest of the floor is 1/4″ ceramic tile over 1/2″ concrete board, so this’ll give me a little overlap when I fill the tile back in against the edge of the new pan.
Do you think that’ll be good enough, or would you do something else? I believe the floor will carry the load of the new pan just fine; that old tub was way heavier — but the pan installers don’t want any flex in the floor when they go to set their pan.
Replies
Sounds like it would definitely help, although the bottom ply would be kind of unconstrained in tension as the pieces would be set in between the beams, if I follow correct. Seems like the top sheet would be doing most of the work- in compression.
You might try tying the edge of the bottom ply to the beams with angle brackets in one or two bays and see if that makes a noticeable difference.
or, to put it another way, rezbump.
k
The area in question starts at the exterior wall and is 48" x 43", or just before the next beam, so the whole area is just car decking over nothing. I like your idea of supporting the lower piece: I could easily put some 2x2 or 2x4 at the edges of the lower piece to hold it up alongside the beams. One side will be best left open so I can get the shower drain past it on the way to the main line. We're kinda tight for vertical clearances to keep a slope. (Have to replace the current 1 1/2" line with 2").
I guess I was talking about lateral displacement for the bottom piece, so 2x's might not help with that (theoretical) problem, especially if the 2x is only on one side. Does that make sense?
Like, as the sandwich bends, the bottom ply is getting stretched, and some gappage could open up where it butts into the beams, if it's not tied to the beams and/or wall.
1/2" glued and screwed (or stapled like crazy)on top is going to do a lot, anyways... and the 3/4 glued to the bottom will be adding something, that's for sure. I guess I'd try the ply sandwich alone, and if it still deflects too much, add some angle brackets (to both sides of the 3/4). You should be able to space them around your drain.
Edited 11/19/2009 6:55 pm by KFC
I think I'll screw the bottom piece on first with 2" screws and then the top piece with 3" screws, which should lock everything together. Then, like you said, if I'm still not happy, back under with some reinforcing from below.
is how the the tub looked when it was in place. Pretty crazy little tub, 43 x 48, about 13" high. Not very convenient to take a bath in, quite small actually. Cast iron, took 3 guys to huck it out of the house.
View Image
Edited 11/20/2009 3:06 am ET by geoffhazel
I think they call that a bidet, qui?
ryder: almost, but no squirty thing that shoots upwards.
that's what she said.
k
Ha!
If you have reasonable access to the underside of this floor system, then why not just add some joists between the beams? Done properly, they will reduce the deflection to WAY less than L/360, and are also a better solution than some plywood.
I won't be laughing at the lies when I'm gone,
And I can't question how or when or why when I'm gone;
I can't live proud enough to die when I'm gone,
So I guess I'll have to do it while I'm here. (Phil Ochs)
I wound up framing in some 2x6 under the floor. The area is only 4 ft x 4 ft. The good part is there is halfway decent crawl space headroom, 24" or so. The bad part is that there was an inch of cold, standing water in a low spot right under the work area. Went back to get the shop vac and sucked enough of it out so that when I laid down some 2 mil plastic, the rest turned to mud and I escaped before I poked too many holes in it. Got dirtier crawling in and out, than I did doing the work. Still put the 1/2" plywood glued and screwed on the topside, and it feels nice and solid now. Bounce on one foot anywhere, still feels solid. I think the shower installers will be happy.