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curbless shower: drain and Kerdi questions

15 years ago

IÂm going nuts with learning about curbless shower installation. Now I need your advice about where to put the drain and the waterproof membrane.

The sketch indicates two possible drain locations: one in the shower and one at the entrance to the shower. The floor outside the shower would be level (i.e., not sloping towards the drain).

There will be no door; a shower curtain is questionable.

IÂve searched the forum and various Google sites, but I need to make sure my interpretations are reasonable.

1. Drain placement questions

I would prefer the drain inside the shower, rather than the trench drain. The drain inside the shower would have slopes in four directions.

Per the NC State University publication, "A shower floor with multiple compound slopes to a center drain is difficult and unsafe for many people, e.g., a person unsteady on his or her feet or someone using a freestanding shower chair or a shower wheelchair. When curbless showers are constructed with a trench style drain, compound slopes in the shower floor can be eliminated and a stepless entry provided".

This one entrance drain would mean that the shower floor slope towards the entrance and in three directions.

Since the shower entrance is not the full width of the shower, would the reduction in the number of slopes make much difference in a personÂs stability?

I do not want to remove the narrow wall. That is, I do not want one side of the shower to be completely open.

Since the shower is so large, would the drain inside the shower be sufficient? Is this inside drain a better idea?

2. Membrane placement questions

How far should the Kerdi membrane extend?

The dashed lines on the sketch are arbitrary limits. A+B? A+B+C? A+B+D? A+B+C+D?

What limits do you suggest?

Perhaps I should ask the question differently:

If a trench drain is used, how far from the drain should the membrane extend?

If the shower floor drain is used, how far from the shower entrance should the membrane extend?

What other questions should I ask, or what else do I need to be aware of?

Should I also post these questions on the plumbing forum? I donÂt mean to offend anyone, but IÂm not sure of who reads what.

Thanks for any help or suggestions.


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