What wood? to use after removing cast iron tub?

Discussion in 'Shower & Bathtub Forum & Blog' started by NoviceLurker, Feb 16, 2021.

  1. NoviceLurker

    NoviceLurker Member

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    Took out my cast iron tub. The replacement is a cast iron shower bed. Where the tub was is recessed about 3/4 of an in and needs to be built up to bring it level to the tile. What should I use to make it level, plywood? Cement board?
     
  2. Terry

    Terry Administrator Staff Member

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    I would use 3/4" plywood to bring the level up.

    [​IMG]
     
    Last edited: Feb 16, 2021
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  4. NoviceLurker

    NoviceLurker Member

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    And just screw it into the wood that's already there?
     
  5. wwhitney

    wwhitney Well-Known Member

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    Depends on what you're laying it over. Slab or wood subfloor? And are you talking about just the footprint of the new receptor, or that the new receptor is going to be slightly smaller, so you'll have to fill in the tile?

    Cheers, Wayne
     
  6. NoviceLurker

    NoviceLurker Member

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    The cast iron shower base is 30x60 and supposed to be a direct replacement for the 30x60 cast iron tub. The tub was recessed about 3/4 of an inch, may be more as I haven't actually measured it, onto wood planks below. The floor is raised about a foot off of the basement floor. Stairs go up to the bathroom. I'll attach a photo that you can kinda see where the tub was.

    bottom left.

    EDECE0CD-3DBA-4FBB-A4FA-6D5881E01D83.jpeg
     
  7. Terry

    Terry Administrator Staff Member

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    It's pretty common for the flooring to go up against the tub and hide where it meets the subfloor.
    It's hard to shim on a remodel that way though. With new construction, you're always there before the flooring goes in.

    Added:
    On older homes there is often sagging of floors making things out of level.
    With new construction, everything is still straight and level. Have you thrown a level on it yet?
     
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  8. wwhitney

    wwhitney Well-Known Member

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    Nothing wrong with leaving it recessed. If you want to raise it up, like Terry said a layer of plywood is the obvious choice. [But you don't want to raise it any higher than the bo Cement board is only useful as a substrate for tile (or for certain application where conditions are too damp for plywood).

    I'd be pleasantly surprised if the new receptor fits perfectly with an even gap to the existing tile for a caulk joint. I would expect that you should have a plan to apply a cove molding or something to cover an irregular gap, if necessary. Although if the tile against the long edge of the opening is straight, and your new receptor has a straight front edge, you could probably position it for that edge to work out and adjust the framing as required. Likewise for one short edge (edit: if the corner angles of the tile void and the receptor match). And if if there's a wall or knee wall for the other short edge, then you could make it all work out.

    Cheers, Wayne
     
  9. NoviceLurker

    NoviceLurker Member

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    Where the white bucket is, there's a 45 degree cut there. The tub was rounded at the edge and when I took it out, there was the 45 degree cut. It's not a perfect 30x60 square. This is the shower base that I got.

    https://www.homedepot.com/p/KOHLER-...h-Left-Hand-Drain-in-White-K-9053-0/100675330

    [​IMG]

    [​IMG]
     
    Last edited by a moderator: Feb 16, 2021
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  10. NoviceLurker

    NoviceLurker Member

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    @Terry @wwhitney

    Did some measurements, and the opening from the studs to the floor is 31.75" by 61.5". So, I'm thinking that put plywood in the opening and make sure it butts up snuggly to the center of the room. Then add bigger studs to make sure the base will end up a little bit on the floor tile? Attaching a 2x6 will will push it too far out. Attaching a 2x4 isn't enough. What I was thinking, not sure if it's recommended, and I believe would be a perfect "shim" is if I screw the 2x4 to the face of the stud that's currently there. Think of it as a T. Is that a viable way to attach a shim? Or should I stack two 1x2 shims on the stud? I will be adding a handicap bar as well and figured if I made a T with the 2x4 that it would be wide enough so the bar will go right into the wood.
     
  11. PlumbNuts

    PlumbNuts SC Licensed Plumbing Contractor

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    Can you just double up on your Durock or drywall? Whatever type of wallboard that you plan to use. Might be easier than firring the wall.
    Perhaps first layer could be 3/4" P.T. plywood? That would serve as your backer for grab bars.

    3/4" plywood
    1/2" Durock
    1/8" thinset
    3/8" tile

    1.75"
     
  12. NoviceLurker

    NoviceLurker Member

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    No risk of mold or anything getting between the Fiberock and the plywood? Also, can't add thinset and tile to the equation as the base goes to the studs, the Fiberock to the lip, add silicone, then tile down below lip.
     
  13. Onokai

    Onokai Member

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    I would use 3/4 plywood to bring it up myself. Thats what is common in new construction as well.
    On the side walls if you need to fir out the studs rip some wood strips to size then tarpaper and then backer board-or forget the tarpaper and use the newer orange tile membranes-as they are waterproof completely.
     
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  14. wwhitney

    wwhitney Well-Known Member

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    Suggest you do nothing until the Kohler shower base is on site. Why do you want to raise up the base with plywood? The T idea would be fine. But the tile substrate should overlap the the base lip, shingle style, even if that means furring out the studs further.

    Cheers, Wayne
     
  15. NoviceLurker

    NoviceLurker Member

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    There is an angle cut on the top side of 45 degrees. I guess I can try to cut the tile and square it, but I don't have the tools to do so? I don't see anything wrong with that except the silicone would be between the middle of base and the floor rather than the bottom of the base and the floor to prevent any water that may splash out from getting underneath.

    Also, the reason I'm shimming it would also make sure there's no plywood showing. The edge of the shower will overlap the tile by about .25".

    As far as waiting, I placed the order first week of January. They "lost" the shower base. Yes, they lost a shower base that's 200lbs, and shipped in a box that's 65"x35"x8". They had to ship another one, and it's not scheduled to be here until March 1st. Trying to do as much as I can so that when that comes, I just pop it on the plywood, build the right wall, Fiberrock it, tile it. I'm going to have to put a full wall up on the right side because the shimming is going to make the shower wall out by about 1.75" from the wall behind the toilet. They're the same wall.
     
    Last edited: Feb 17, 2021
  16. NoviceLurker

    NoviceLurker Member

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    And now that I'm looking at the installation guide again, you're supposed to furr it and the Fiberock overlaps the lip and then the tile goes just a littler further down.
     
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  17. wwhitney

    wwhitney Well-Known Member

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    Are you saying the edges of the tiles at the opening are beveled, or are you saying that in plan there's tile in the way, i.e. the opening is a rectangle with a corner cut off? A picture would help clarify.

    So you're thinking of setting the new base on the top of the tile? Are your sure the cast iron glazing goes all the way to the very bottom of the unit, and that there isn't an unglazed 1/8" or whatever at the bottom? Because the usual thing is to set the tub/receptor on the subfloor before the finish floor is installed, and the the finish floor butts up to it.

    If your wall has a 2" jog in it, there are certainly ways to handle that gracefully, if you'd prefer to have a knee wall with glass on top.

    Also, you might consider the option of setting the receptor back against the existing framing, and dealing with the gap in the tile somehow. E.g. find a closely matching new tile. Or (very hard) non-destructively remove the tile under the new flanking wall between the receptor and the toilet, and reuse it. Or cut the tile back and infill with a coordinating tile material.

    Cheers, Wayne
     
  18. NoviceLurker

    NoviceLurker Member

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    Cast iron is 100% to the bottom. Their instructions have it on top of the flooring.

    There's not going to be any glass in this. It will be a curtain. I had glass in another bathroom, it cost me $4000, and it exploded three years later for absolutely no reason. Not doing that again!

    Here's a diagram of the bathroom. Artboard 1@4x-100.jpg white-kohler-shower-pans-k-9053-0-a0_1000.jpg
     
  19. wwhitney

    wwhitney Well-Known Member

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    Sure, the whole thing is cast iron, but on at least one tub I've seen, the glazing didn't quite make it all the way to the bottom of the fixture. If it were set on a finished floor, there would have ben a hint of unglazed cast iron visible. Although I guess a heavy cove of caulk would cover it.

    If you read the instructions, the last step after receptor installation is "install the finish floor", so they are expecting it to be installed on the subfloor. With the finish floor butting up against it (should be a caulk joint).

    So I think it would be best to cut out at least a little tile to make your opening rectangular. A steady hand with a diamond wheel in an angle grinder would do it, although it would be dusty.

    Or raising it up to sit on top of the tile would work, if you could install a transition or cove on top of the tile against the "skirt" of the receptor.

    Cheers, Wayne
     
  20. NoviceLurker

    NoviceLurker Member

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    I now see two different installation guides. One says backer board goes to lip. Another says to shim to lip. I'm gonna go ahead and say the backerboard goes to the top of the lip, not overlapping it.

    In both sets of instructions they say "install the finished floor."

    I was thinking that and putting some sort of white bullnose around the bottom if I built the floor up. Then again, if I put the base recessed I'd still be doing that anyway. Do you have another suggestion?
     
  21. NoviceLurker

    NoviceLurker Member

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    And I can't thank you guys enough for all of the information and these forums. They're very helpful.
     
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