reduce size of cutout in cultured marble shower to match new valve trim plate gasket

Discussion in 'Shower & Bathtub Forum & Blog' started by lifespeed, Apr 19, 2012.

  1. lifespeed

    lifespeed Member

    Messages:
    329
    Location:
    California
    I am in the middle of a re-pipe. All is going well so far, but the rocket scientists who installed the shower cut a rather large horizontal oval hole for the old shower valve. The new Toto valve and trim plate is narrower, so the gasket under the trim plate won't quite seal because the oval hole is too wide. I need to make the hole in the cultured marble narrower. Yes, I know it is much more difficult to decrease the size of a hole compared to enlarging it.

    Is there some sort of durable material that is compatible with synthetic marble that I can use to build up the edges of the hole against a flat plate "mold" so that I end up with a hole that is not quite so wide, and a good solid flat sealing surface for the trim plate? I really don't want to just squirt some silicone or caulk in there, as we know that is never a long term fix. I believe the factory Toto foam rubber gasket is the way to go, I just need a good surface for it to seal against.

    Epoxy resin with fiberglass is one thing that came to mind, but that is a bit thin for this type of work. I probably need something with body too it to hold it's shape while it cures on this vertical surface.

    Any ideas or experiences?
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,269
    Location:
    New England
    If the valve was already installed, my personal opinion, they owe you a new piece to replace what's there. Or, someone to come out and do a repair. When used as a countertop, those guys can join pieces which is nearly impossible to find...it can be done, but you probably can't buy the materials or have the experience to do it.
  3. lifespeed

    lifespeed Member

    Messages:
    329
    Location:
    California
    The rocket scientists are long gone, I am re-plumbing an existing shower. I will try and contact a countertop expert, although it may be difficult to find anybody interested in work that is not a $40K+ kitchen remodel :(
  4. Jerome2877

    Jerome2877 In the Trades

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    397
    Location:
    BC
    A reno plate would be your easiest and cheapest option. reno plate.jpg
  5. lifespeed

    lifespeed Member

    Messages:
    329
    Location:
    California
    That plate is not compatible with my Toto valve. Toto_TS960C1.jpg
  6. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,269
    Location:
    New England
    There are places that do repairs to SS materials...they're used to smaller jobs, but it's the same skills that are used to seam counters as it is to repair them.
  7. lifespeed

    lifespeed Member

    Messages:
    329
    Location:
    California
    I think I am going to go with marine epoxy putty molded around a couple stainless screws drilled into the cutout edge parallel with the slab. I will use a plastic sheet as a mold for the interior shower surface to arrive at a finished surface that is strong, waterproof, and level with the rest of the slab.

    My hope is this will provide a good surface for the trim plate gasket to seal against.

    Isn't it amazing how when you examine work done on a house by the previous owners, 95% of it appears to have been done by chimps?
  8. Hackney plumbing

    Hackney plumbing Homeowner

    Messages:
    1,174
    Location:
    Alabama
    If it is cultured marble there is no way to make hidden seams. You can make nice seams but they will never disappear like a solid surface material like Corian. The color will never match with cultured marble either.
  9. lifespeed

    lifespeed Member

    Messages:
    329
    Location:
    California
    I'm sure you are correct. However I just need a surface for gasket sealing. It won't be visible as it does not extend beyond the edge of the trim plate. The trim plate gasket is smaller than the trim plate and this is where the problem arises.
  10. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,269
    Location:
    New England
    If it won't be visible, pin and epoxy some similar material on there to make a flat surface. A flat board with some plastic wrap on it would help keep it flush while curing, then peel away when done.
  11. lifespeed

    lifespeed Member

    Messages:
    329
    Location:
    California
    Fixed!

    I fixed it with Devcon marine epoxy putty and some stainless screws drilled into the edge parallel with the cultured marble. No leaks, appears very durable. Here is a photo after the first side is finished.
    epoxy_putty_small.jpg
    Last edited: Apr 23, 2012
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