Ken, I believe you are preparing to recess your shower pan area. There is a "lot" to the specifics, prep and existing conditions but here are a few pics to give you an idea. In this case i was building a barrier free shower, with the drain location and rough in specfic for the brand/type linear drain ill be installing. From here i will pour a bonded preslope of screed mud and topically waterproof .. - best

There are a couple of code requirements for shower floor elevations;

1) There needs to be a 2" elevation difference between the top of the curb and the top of the shower drain. Meaning, with the drain plugged, the shower should be able to hold a 2" depth of water directly over the drain without water flowing over the curb and into the bathroom.

With a curbless shower in a non-wet room, the "top of the curb" will be the shower threshold entry, where the flat bathroom floor tile transitions to sloped shower floor tile.

2) Shower floor slope. The slope needs to be between 1/4" per foot and 1/2" per foot. Easiest way to get in that range is to use a linear drain.

And I'll add in a third, that the waterproof membrane itself need to be pitched to the drain. Having a flat membrane with sloped mud and sloped tile above it does not count. The membrane itself needs to be sloped.

Easiest way to accomplish this is to do what Tundra did:

1) Drop the elevation of the repoured slab under the shower footprint by a few inches. Three inches gives you some leeway, but with elevation drawings and a knowledge of your floor component thicknesses, you can get it closer to minimize the amount of mud needed to create the final slope.

2) Set your rough drain elevation, then use a proper thick bed material (deck mud for example) to create the slope to the drain. I don't advise trying to pour the slope with concrete. It'll slump on you, ruin your slope, and you'll have a mess. Deck mud is easiest and the most precise, being you can shape it as needed. Look at Tundra's photos and use them as a baseline to follow.

3) Use a topical membrane over the sloped mud. There are sheet membranes, there are liquid membranes. People have their preferences, but they both work fine.Consider extending the membrane out of the shower and on to the bathroom floor a few feet.

4) Consider adding a capillary break at the shower threshold (where the sloped shower floor tile transitions to flat bathroom floor tile) to prevent any moisture that wets the shower grout/thinset from wicking into the bathroom floor grout/thinset via capillary action.

I wrote more than you asked about. But I do tend to ramble.

Mongo, Tundra,

Thanks to the both of you. Part of my concern was how to accomplish the slope with concrete. I'll be blunt, my concrete skills suck and pouring a sloped pad was likely to be well outside my skills range. Tundra, thanks for the pictures, they clarified a great deal. It's true that a picture is worth a thousand words because I don't know how you could describe what you did without at least some drawings but the pictures tell the tale just fine.

My current working thought is to pour the pad in two stages. The first would be about 2 to 2-1/2" below the existing grade. The other would be 2" below that. The demarcation like would be the beginning of the shower enclosure area. The purpose of pouring it so low is so that I could use deck mud to create a dual slope from the edges to center and from right to left (as seen from diagram). I was thinking 1/8" per linear foot of drop for the primary bathroom area and somewhere in the range of 1/4-1/2" drop for the shower proper. I would mud out the preliminary slope with it all rolling into the weep holes of the drain assembly. I would then membrane the whole thing. I'd membrane the walls in the primary bath area up to the 4' mark since that's how high my tile is going to go. I'd membrane the shower area all the way to the ceiling since that's how high the tile will go in there. On top of the membrane I'm planning to make a final deck mud slope that I would then thinset the tile to. I'm using 3/4" pennyround mosaic for the floor and ceiling so adjusting to the slope won't be an issue.

As I said, that's the current mental formulation, pending feedback and ideas. As with all battle plans it's not likely to survive contact with the enemy.

Mongo, don't fret about rambling. As you might have noticed I'm a bit on the verbose end of things myself.

To Mongo and Tundra, thanks again for your prompt response and insightful advise. It was, in part, your commentary on other threads that led me to post this question on this forum. Cheers.

Ken,

There is a few major factors to consider in regards to assembling your shower. The drain brand and type (its either a bonded flange drain or a Linear drain strainer that works with a clamping drain and that is a major point in the build and drain rough location as you cant get the clamping drain as close to back wall., secondly the whole waterproofing system (walls and pan) and how that interteracts with the change of plane and drain connection.

Before moving fwd id make sure that checklist is set and well planned, also consider how you will set/space framing plates in relation to finish wall thickness and the new recess of the pan and waterproofing.. I would likely cut out and recess a larger than needed pan and also incorporate grading from aprox 6-12" outside of the shower (although your door location is not ideal) i may swap glass around too)). A full capillary at the edge of grading or just past glass is very smart as well..

another pic to help

on this curbless linear prep job we started with a 4" drop in elevation , the preslope or grading is out to the edge of the white skimcoated membrane you see (well beyond where the showers glass will end up.) This mud pan is waterpoofed with bonded Nobleseal TS that is tucked behind the cement board and connected or "tied into" the blue Hydrobarrier wall waterproofing as well as bonded directly to the Linear drains flange.....maybe that gives you more insight to the build of it -Best