Please Help. Drain Installation for Tile Shower

[emcconne]

Hi all. Sorry for asking such a simple question but the instructions included with the shower drain are not clear at all. I'm installing a tile shower drain before the pre-pack gets poured for a custom tile shower enclosure, however I'm not sure which part of the drain should rest on the subfloor. The subfloor is actually 1/2 + 5/8 plywood if that matters. Here is a picture of the drain. Please help. The tile guy is supposed to start on Monday :|.

[N2plumbing]

In your picture, the top part you marked is the bottom of the drain flange that fits flat on your subfloor. The divots are for the flange bolts and you can notch the floor to fit them in. Be sure to set it plumb for your tileman.

[hj]

The top of the "dish" where the bolts are should level with, or slightly below, the "prepack" so that the liner drains into it.

[johnfrwhipple]

We like to use a palm router and set this type of compression drain so the drain base (portion without the top compression section and grill) is dead level with the subfloor. Installations like this are tricky as your preslope would need to slope to a feathered edge.

Are you building a pre-slope? You Should.

Depending on your setting materials you may want this height raised to 3/4" above the subfloor to allow for a common deck mud (4-1 , 5-1) type mix.

Often builders will have the plywood base pre-slope first so the answer to your question comes with many questions of their own.

If your floor has a lot of delflection I would be reinforcing it a lot. If this is not possible I would be planning for minimum 3/4" od deck mud and the low point of your pre-slope and building up at 1/4" per foot to the edges.

Make sure the weep holes do not get clogged. Pick up some candle wick to keep them clear.

Good Luck.

JW

[jadnashua]

Deck mud over a plywood subfloor needs some thickness to survive, this is why the clamping portion of the drain needs to be above the subflooring height. As mentioned, at least 3/4", and an inch if possible. Then, the liner gets installed, then the setting surface. Did you put in blocking and notch the studs to allow the liner to sit flat and not bow out around the edges? The setting surface ends up being a constant thickness, since the preslope is already sloped the proper amount. The details of how to do this can get specific, and if done wrong, you'll end up with a leaky, and/or smelly shower. You want the setting bed to be at least an inch thick, too. This will somewhat dictate how high the curb must be. Many people assume that the tile is the waterproof layer, but it is not, the liner is, and it must be sloped and the weep holes open, or you'll slowly accumulate stagnet water underneath the tiles in the mudbed. This is one reason why I prefer a surface membrane (Hydroban, Kerdi, Nobel, etc.). this puts the waterproof layer immediately underneath the tile, and there's much less that can get wet.