Schluter's Line Drain - A closer look at the new linear shower drain from Schluter

Discussion in 'Shower & Bathtub Forum & Blog' started by johnfrwhipple, May 12, 2011.

  1. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

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    Posts Gone

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  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Problem with any waterproof membrane and essentially an impervious porcelain tile (glazed ceramic can still be a problem, but not as big) is that a modified thinset needs to both dry and to cure. It only has the grout lines to dry from, so it's similar to the effect of using mastic and large tile...it takes excessive amounts of time to be stable. An unmodified thinset doesn't have these problems. The difference in 'stickiness' between a premium unmodified and a modified in total strength isn't all that much, relative to the scheme of things, as either is more than enough in most circumstances. Schluter has given permission to use fast setting modifieds in special circumstances, but these are best left to pros verses the more typical slower DIY'er.
  3. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

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  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    I think that it's just that the company is conservative...they don't want a failure, and they are sure it works with an unmodified. If a modified is used, and it hasn't dried properly, you can compromise the bond - I don't care whose membrane you use - moisture doesn't go through it, and neither does it go through the tile (at least very fast), and it WILL take excessive time to properly bond. If the tile is disturbed before that happens, you can have a bonding failure. A modified between impervious surfaces is almost like a mastic...on larger tile, it can take weeks to dry out and approach what an unmodified achieves in a day. How many people are going to stay off the surface for that long? Yes, the rapid set stuff (at least the cement part) cures rapidly, but if properly mixed, those sand and cement particles are coated with the modifiers, which don't reach full strength until they dry.

    While many people may know you should remix a modified after slaking, most (IMHO) do not know why. The modifiers must hydrate so they can flow properly to coat the sand and cement particles. That happens, not in the first mixing, but after slaking and during the re-mix - they absorb the moisture and become stickier and can flow while remixing. If the second mixing is done too soon or ommitted, the thinset will be considerably less strong and have a very different texture from when the instructions are adhered to. Some people tend to add more water than specified trying to get the texture what they want. This weakens the mix. If the proper mixing, slaking, and re-mixing times are adhered to with a proper paddle and speeds, they'd most often find the prescribed water content is right on. This info comes from manufacturer's reps as received at a class at the TCNA school. Old habits die hard, and many people (pros included) do NOT mix their mortars per the instructions. They'd be surprised at the differences if they did.

    It is a tribute to the mortar manufacturers that ANY modified thinset works when sandwiched between a waterproof membrane and a highly impervious tile.
  5. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

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  6. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

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  7. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

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  8. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

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    Close Up Pictures of the Schluter Linear Drain

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  9. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

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  10. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

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  11. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

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    Weak Point in the Kerdi Linear Drain installation

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  12. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Since any water on that edge will drop into the drain and not puddle or pool there, a token seal provided by the narrow band should be more than enough. The same can't be said for the junctions of walls where tile and tile could meet. I'm assuming that the metal has a slight angle to it towards the drain. Since the metal won't wick and the Kerdi is hydrophobic, that band should be plenty. My opinion only.
  13. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

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  14. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

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  15. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

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