Kerdi over a mud bed would be far superior to a Tile Redi pan. Solid underfoot, no flexing, and no issues where the pan meets the walls.

A mud bed isn't technically difficult. But it can be tiring. My shower is a little larger than yours, 5' by 8'. Kerdi too. Mud slope but cement board on the walls.

Here's the old thread.

Hi Mongo,

Thanks for the insight. I think I am going with the mud bed, I am up for the challenge. I was discouraged about the Kerdi at first because they did not have the size shower pan to fit my shower. But after reading your post is what made me want to do the Kerdi over a mud bed.

Thanks,
Steve

Steve,

I've used the Kerdi Trays, and while they are easy to use, there's a little weirdness to them. Sort of like a floating floor, they can sound a little "hollow" when water hits the tile, but that can depends on the shower head used and the type of spray that comes out of the head. When I've used the Kerdi Trays to advantage is when I had multiple showers to do at once. I framed the showers a uniform size and down went the trays, boom, boom, boom. Done fast.

I do prefer a mud bed versus using the Kerdi Tray. But that is simply my opinion. Nothing wrong with the trays.

Mud slopes aren't horribly difficult. Just set your drain elevation. Set your perimeter wall mud height. Then fill in the in-between part. The beauty of deck mud is that it's lean enough that you can shave it here and build it up there while you work it.

For your first attempt consider having a few screed boards or straight pieces of scrap wood of varying lengths that you can use to screed the mud or use as sighting boards to keep the mud flat as you work the slope from drain-to-wall.

There are also commercially available sloping kits, essentially sloped screed boards. Or you can cut your own tapered pieces and use them to help you hit the slope.

Humps in the sloped floor can be shaved down. If you have a divot/depression, do not accept it. Fill it in prior to kerdi-ing the sloped floor.

If the "discouraged about Kerdi" comment indicates a dissatisfaction or trepidation with the Kerdi product itself, there's a hybrid approach that has been discussed a few times using a sloped mud bed, a kerdi drain set in the mud bed, cement board on the walls and HydroBan (instead of Kerdi) to waterproof everything.

Put a few beers on ice. You'll be ready!

Best, Mongo

Mongo,

The only reason I was discouraged was because of the tray size not available for my shower size. I did not know about putting it over a mud bed until I stumbled across your marvelous post with all the wonderful info in it. I definitely want a custom shower and do not want to be constricted by the size of a pre-built pan. I have done a little research on the Hydro-ban, but really like the idea of the Kerdi drain.

Is it a minimum of 1/4"/ft on the slope? And I assume I will take that off the longest point away from the center drain. So the shorter sides will have a little steeper pitch.

I am excited to start this project and look forward to all the expertise on this board when I stumble onto a problem. I also stumbled across some pictures of your bathroom in one of these posts, and WOW, may I say what a work of art.

Thanks!!!!

Yes, the floor slope requirements are for the pitch to be between 1/4" min and 1/2" max, and you need a minimum of 2" vertical elevation between the height of the top of the curb and the elevation of the drain. Meaning, plug the drain and the pan should hold a 2" depth of water at the drain before water overflows the curb.

Thanks, my bathroom has held up well over the years. If only I could be so lucky!