Install Tile Shower Base Drain -- Advice Needed
 

As part of a complete bathroom remodel, we are installing a tiled shower to replace a paneled shower with fiberglass pan that we have removed down to the studs. We haven't done this type of work before but follow direction well. : - )

We plan to build a mortar shower pan.We need advice and suggestions on how best to modify the existing shower drain plumbing to accomodate the new Oatey ABS drain for tile shower base.

Attached are pictures of the current setup.

Pictures 1 and 2 - Shows too large hole in existing plywood floor and existing riser. The water level of the drain trap sits at four inches below the top rim of the riser.

Picture 3 - Existing riser with Oatey drain assembly fitted on top. The ruler shows the distance from the subfloor to the drain assembly.

Question One - Since the hole in the existing subfloor is too big, should we install a half inch piece of plywood over the existing and cut out the four and one-half inch hole that is required, or is there a better way to get the correct size hole?

Question Two - It seems to us that approximately two and one-half inches of the existing riser needs to be removed to allow the flange of the tile base to sit on the subfloor. (Two inches if we install the additional half inch of plywood.) This will result in the water level of the drain trap sitting at approximately two inches below the top rim of the riser. Is this OK? If not, what do we need to do?

You folks are our "go to" guys for this project. Any help, advice or suggestions will be most appreciated.

need pics

Missing pictures
 

Sorry -- forgot the pics. I uploaded two of the three -- one was too large.

Questions are in previous post.

TIA!

A new piece of 3/4" ply would work also. Cut it from center to center along the joists. Your right the hole is too big and the flange sits too high. The bottom of flange needs to sit on top of the plywood.

but they are using a mud base... how thick should that be? and doesn't the flange height depend on the thickness of the mud base?

The type of drain they have is adjustable, it screws up and down from it's base. Done properly, the pre-slope will be appox. 1/4-3/8" from the base of the drain to appox. 1" or so along the outside walls. The mud base itself should be at least 1 1/2". The overall thickness depends on the length and width of the shower in order to maintain 1/4" per foot slope.
From the plywood up:
Tar paper (stapled)
Metal Lath (stapled)
Pre-slope (3:1 to 5:1 Sand Mix) (packed well)
PVC Liner
Cement board on walls
Mud Base (3:1 to 5:1 Sand Mix) (packed well)

On the curb I use Mortar mix and metal lath around 2x's.

Shower subfloor and drain now ready for mortar pan work
 

Thanks for the help!

We got it done as follows -- Cut appropriate size drain hole in sheet of 3/4" plywood and added it (glued and screwed) to existing 3/4" subfloor in shower. Cut down existing ABS riser pipe to allow flange of Oatey drain to rest on plywood floor and installed.

Next is building the mortar shower pan.

Don't forget the curb.

Shower Curb
 

Yep -- the curb is what my husband is working on as I write.

He's putting in three 2x4's aligned so that the front of the curb will be on same plane as the front wall (along the black line you can see in picture that accompanied previous post) when tile has been installed.

As you can also see in that same picture, the sheet of 3/4" plywood that was added to the shower floor stops at the point the 2/4's start.

On the bathroom side of the curb we plan to install 1/4" hardiebacker over the existing subfloor.

Tomorrow is probably mud day. Wish us luck!

Here is a link to a tiling site--Shower Construction Info (a collection of posts) - Ceramic Tile Advice Forums - John Bridge Ceramic Tile

There you will find good instructions on making the 'dry pack ' mud.

Thanks for the mud recipe
 

Thanks for the link. Good info. I also found one by JB specific to the task of building the curb. Also very good.