Mixing Kerdi and mortar beds in new shower

Folks,
I'm building a custom shower (78" x 40").
My drain is about 23" from one end.
I was thinking about using a 48" x 48" kerdi shower pan (and cutting it to fit the drain end of the shower) and then using a mortar-sand bed for the remaining shower floor area (about 30" x 40" or so) at the other end.

Is this doable?
Some say not to mix the two systems.
Others say go ahead.
Any advice?
I figured that once the tile is over both, there wouldn't be much difference.

Help?!

J.

The Kerdi tray has a fixed slope built into it; if you extend one side (with a mud bed) then to maintain the proper slope the far end of the bed will be about 5/8 inch higher than the opposite end of the Kerdi tray. The tiles on the mud bed end will be cut 5/8 inch shorter than the ones at the Kerdi tray end, and the ones along the long walls will have angled bottom cuts. You'll get better results with a mud bed for the whole area (and save the cost of the expensive Kerdi tray).

You might want to wander over to the John Bridge tile forums (http://www.johnbridge.com/vbulletin/forumdisplay.php?f=1) - there a LOT of knowledgeable folks there.

the tray works well IF you can cut or add (nearly) the same amount from all sides. Ideally you want the drain in the middle, too so that the slope is similar from each end. You should try to have the outer edge the same height all the way around. That means in a rectangle, the shorter side will be steeper.

Thanks Guys

Wow!

Thanks Guys for the great information.
John, your diagrams and suggestions are outstanding (especially for my novice brain).

We thought about the extended 60x30" Kerdi drain but the drain doesn't line up.
The idea about the Proslope is new. And it can be used for the 78 x 40 without any problem?

With such a gentle slope, is it THAT difficult to tile? We're using the 2x2" tiles on the shower floor.
The door is on the top left of your diagrams (and is about 28" wide).

Thanks for all the help..I'm overwhelmed!
Cheers,
J. Norrie (Nova Scotia)

p.s. One last thing, is it out of teh ordinary to mix the Kerdi or Proslope systems with mud beds? Does it affect the "walking" texture or feel of the shower floor?

If I was going to do this and was using kerdi, I'd build it all with deck mud. If I could, I'd center the drain.