Kerdi membrane question

Discussion in 'Shower & Bathtub Forum & Blog' started by khayes, Mar 27, 2007.

  1. khayes

    khayes New Member

    Messages:
    53
    Location:
    Alpharetta, GA.
    Does anyone know if one can use the Kerdi membrane with a prefab shower pan? I'm taking a week to remodel my daughter's bathroom in another state and I want to use the membrane as a wall tile underlayment. I would like to use a prefab shower base to save time and for the other reason that I have never tiled a shower base and am scared to try!
  2. yes

    using some of one company's product and some of another's, is done all the time.

    A pre-fab is a regular shape like a square or a rectangle, so you can also use a Kerdi pre-fab (square or rectangle) and tile it. Lining up tiles so that they are all flush to one another is why you have a trowel with grooves in it. The floor is not a challenge.

    Where the walls meet the tray is where water will drip off, and using a pre-fab means you make sure the walls are positioned close enough inwards to ensure water will drip into the tray and not down the backside (outside) of the tray edge.

    david
  3. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,270
    Location:
    New England
    You could do it, but it is better if you use the entire system which includes the drain. While thinset might hold the bottom edge to the fiberglass, that would be the weak link. The fiberglass pans tend to be pretty flimsy. If you do use one, make sure to fully support it underneath, or you will be looking at stress fractures in short order. You might want to order a tube of the Kerdifix, a urethane adhesive designed to attach Kerdi where things might flex and thinset won't be reliable. If you can use their preformed pan, then I'd stay away from the fiberglass pan and use it instead. It depends on the size and shape of the shower and where the drain is located. You can cut their pan, but you should try to cut it symetrically and the drain needs to be as close to the center as possible. There is not much slop in where the drain can go unless you make a custom pan. Check out www.schluter.com for the specs and a video on installing the stuff.

    You should also check out www.johnbridge.com. They have an on-line source for the Kerdi stuff if it isn't readily available where you live. If you want to avoid any caulk in the shower, schluter has some neat expansion joints designed specifically for that. The advantage of a Kerdi shower is it puts a waterproof membrane immediately under the tile so there is very little in a shower that can absorb moisture. The whole thing dries out much quicker which means less susceptability to it growing mold or leaking.
  4. khayes

    khayes New Member

    Messages:
    53
    Location:
    Alpharetta, GA.
    Thanks guys - Jim you addressed exactly my concern, joining the membrane to the pan. I'll check into using the Kerdi pan - does it require tile? I'm trying to avoid tiling the floor. The drain location is not really a concern as the shower is over a crawl space with excellent access. I can relocate the drain if needed...but it's centered in a 36x36 opening.
    Thanks again - great forum.
  5. why avoid?

    With a kerdi pan, you can use large tiles for the floor too. The pan (tray) is made of four flat planes that meet at the drain.

    tiling a floor is just as easy or hard as tiling a wall.

    it's a small surface to tile.

    hope this helps explain why it's not a big deal to tile a shower floor.

    david
  6. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,270
    Location:
    New England
    Smaller tile offer more grout lines for your feet to grip, but larger tile can be used. You may need to split some along the diagonals.
  7. either you cut a lot of them, along the four diagonal lines, or if you tile the floor on the diagonal, you cut a lot of them to make the wall edge and to go around the four sides of the drain. This latter option is good for a tile beginner; it avoids having two cut diagonal tile pieces face each other.

    6"x6" tiles are a good size in a 36"x36" space. That is large enough.

    Make sure the tile is designed as a floor tile.

    david
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