You are completely out of your depth and do not have a workable plan, or proper dimensions for a workable plan. Guaranteed water damage from improper containment. To do what you want involved turningvthe entire bathroom into a wetroom, with the “shower curb” transferred to the bath entry point. Then the tile layout is critical, as is choosing the correct COF rating. Otherwise your accessible bath is a death trap.

You need to hire a Pro who can do the numerous structural and plumbing alterations needed for your wish.

That was helpful.

I have had considerable success in my 57 years starting from a point of "out of my depth". And for the first 50 years there were no YouTube videos.

I would be grateful if you could unpack that answer a bit.

I'm not trying to make an accessible bath.

I want to use large tiles, that brought me to a linear drain. I could still make a curb if i have to but the bathroom is a bit on the small side so i want to avoid breaking it up with a curb to create more visual space.

There are no pluming and structural alterations i can't handle. Just need to know what they are.

Please continue.....

Dave what components do you have. Specifically. A photo would be helpful.

I have a 6' X 8' membrane and associated adhesives and sealant. I have 45" by 36" framed in stall that will be a shower.

I have not acquired the linear drain yet but it looks like the picture.

I'm thinking I will run the mebrane out the shower opening, cut and seal it to the flange and then mud up to the sides.

But for all the step-by-step videos on you tube, I could not find one for this.

How are you going to get water to run downhill to a drain from two directions on a flat floor? A linear drain against the far wall only needs to deal with a single slope. Plumbing code requires between a 1/4” per foot slope to a max 1/2” per foot slope. And the entry of the shower needs to be 2” higher than the drain. How do you plan to make that floor slope happen when you haven’t even talked about the structural alterations needed to create the proper slope.

Dave-

I don't have experience with a curbless shower, but I do have experience with a linear drain placed in the center, and it works just fine. I have a slightly larger shower than you which I had re-tiled 2 years ago. The original tile was 2"X2" on a mud bed tapering to the center drain. The new tile was 12"X12", which can't be done with a standard center drain, but works fine with a linear drain. You just need to have the linear drain span most of the width: then you have two flat planes sloping in from each end and they get tiled and meet in the center at the drain. My slope from each end is the standard 1/4" per foot, so my 7' long shower is a bit less than 1" higher at each end than in the middle; your 40" long shower would only need to be 1/2" higher at each end. Make sure when you are finished tiling (including the walls) that you have allowed for a bit of clear space on each end of the linear drain so you can pull the drain plate off when you need to clean the drain. If you have a 36" space, go with a 30-34" linear drain, or if you can widen the space to, say, 37", a 36" linear drain is doable. My shower measures 56" wide and I used a 48" linear drain, with about 4" of clearance on each end. Here are a couple of pictures of my shower so you can see what happens with the tile when it meets at the center:

The only other thought I had is that your shower, though of decent size, may be too small to prevent a lot of water splashing outside the shower unless you have at least a minimal curb.

To drain the water from the shower I will slope the mud 1/8" per foot

On the other side I'll just tweek the thinset a bit.

Also, no 2" height requirement in North Carolina

Dave-

I don't think that will be enough to drain properly, but your call.

I'm not married to that number, 1/4" would be OK

It needs to be at least 1/4" slope.

North Carolina water still obeys the laws of gravity and capillary action. Yes, the 2” requirement exists, whether or not it’s enforced by your state or common sense either one.

I think we are misunderstanding each other.

The shower stall is 36" wide by 40" deep. A 6' X 8' membrane will go up the walls and out into the bathroom.

So where does the 2" number come from?

A 36" linear drain will be siliconed in at the opening of the shower.

The shower floor will have a layer of mud going from 1 3/8" thick at the far end, tapering down to 1/2" at the drain to match the adjacent cement board.

The question is, how much water will splash off a naked human and how far will it travel? If lots of it goes beyond 40 inches then I will have to add a shower curtain.

The other question is what are the pathways for water intrusion that I have not addressed?

What brand of membrane are you using? Make sure it's compatible with the drain. Your membrane/drain combination may call for a certain proprietary sealant, not a basic silicon caulk.

"So where does the 2" number come from?"

That's from basic building code for showers. Check out the code for shower pan construction, as well as the section on required flood testing. Even if code does not apply in your area, following code, or at least being aware of it, can help you meet a minimum standard for construction.

"The other question is what are the pathways for water intrusion that I have not addressed?"

Not sure of your overall plan, you may already be planning on this, but consider a capillary break at the shower threshold to prevent the water wicking from the thinset and grout in the shower floor out into the thinset and grout in the bathroom floor due to capillary action.

Find out from your AHJ if you can have a linear drain at the shower entry. Some prohibit it. If allowed, select your drain grate wisely. Some grate designs can allow water to wash over the grate due to sudsing action and flow into the bathroom.

"The question is, how much water will splash...how far will it travel...beyond 40 inches then I will have to add a shower curtain."

You should be fine there unless you are an excessively vigorous bather.

You have not addressed the slope of the bathroom itself to the drain. Because it is required to be constructed as a wetroom due to the drain placement at the shower entry, you are required to have at least 2” of drop from the room entry to the drain. You will likely need to use the steeper 1/2” per foot slope for that drop. And the room entry will now be at least 2” taller than the hall. 2” is achieved at 96” at 1/4” per foot, or at 48” at 1/2” per foot. Basic math.

Vinyl liners do not really work with any large custom shower application. You need topical applied waterproofing such as a fabric or liquid membrane system. For the entire bath, since it must be a wetroom.

Most people who want curbless use the linear drain at the far wall from the shower entry, and make the shower at least 48” deep. That ensures the 2” drop from shower entry to drain is maintained. Waterproofing 8-12” outside the entry, with a capillary break will allow the entry to get wet, as it will, and not have that water wick through the thinset or grout to the non waterproofed floor sections.

There are a LOT of incorrect videos on YouTube for just about anything you can name, from knife sharpening to building model airplanes, to setting tile. Relying on something like that is not the best idea should you want your home to remain mold and rot free.

As mongoCT stated youll need a membrane mil thickness to be able to clamp in that drain . Nobleseal TS and valueseal meet the spec. other than pvc liners I know of no others...... Bad drain choice for lowering elevation. Im sorry but i fear your in too deep....

The walls must also be waterproofed. Not just the pan. With your smaller shower dimensions, a short curb would be much easier to DIY than doing the required wet room build. You would still need to waterproof the walls, but you won’t have the numerous issues that you are just beginning to run into with curbless.

You may want to engage a knowledgeable Pro for this. Good luck!.

Do you mean the rest of the bathroom walls? I should probably post a photo of the layout. I don't see that much water escaping the shower area. Certainly no more than leaves a bathtub when an 8 year old boy uses it.

Certainly the shower stall walls will be sealed. I'm using a Lowes product just called "Membrane" - it gets brushed on.

Anyway, this is a rental, It needs to be pretty and functional but if I have to rip it out in four years for a new tenant it's not the end of the world.

LOL rip out my investment in 4 yrs??Huh? we are in a new age people

Why on earth would you attempt to do even a correctly done curbless for a rental? Much less an incorrectly done one? Science experiment for mold? Just shove a cheap $100 steel tub in there with some acrylic wall panels and be done.

We lived in this house for 10 years, we kinda like it so now that it's empty I'm making it as nice as i can. We may move back in when the boys are older.
i have two other houses that would benefit from a custom shower so what i learn here will be reapplied.

Thanks for all the input. I will update this for your curiosity.

Dave, It would be best to contact manufacturers of barrier free shower systems directly for information. Codes have not caught up with real world applications. Which makes the comments you received here from others valid. I would not dispute any of the above statements as they are based on current codes. But there is no denying what can be done. IMO. I have not had a building inspector to date not approve a barrier free system. Always verify acceptance by the local official prior.

Is this a diy forum or not?

I work with engineers, we build military airplanes.

Making water flow downhill just ain't that hard.

Is this a diy forum or not?

I work with engineers, we build military airplanes.

Making water flow downhill just ain't that hard.

Anyway, this is a rental, It needs to be pretty and functional but if I have to rip it out in four years for a new tenant it's not the end of the world.

Its always the engineers that think they're smarter than the rest, Its rare someone so smart is on this mess of a forum seeking and refuting sound advice.

I dont know one engineer or successful real estate investment advisor that would back your theories here. Are you here asking for help or telling us how its gonna go and wanting applause?

Joe’s Double Secret Probation for sure. And flunked it.

Yeah, making water run downhill IS that hard within the required constraints. You are required to maintain a 1/4” to 1/2” slope for a shower, with the shower entry at least 2” higher than the drain. Anyone who can do trig out to be able to do the basic math and come to the conclusion that you need at least 48” from the shower entry to the drain. Usually against the far wall from the entry, as most people don’t have room for an 8’ shower.

Thats called a wet room, and it’s why most people do not place the drain at the shower entry. It creates the necessity to waterproof the entire room as a wetroom. The “shower entry” becomes the threshold into the room. Which is then higher than the Hall and creates its own set of obstacles to someone needing curbless.

PVC liners ain’t gonna cut it. They don’t cut it anymore for a regular shower build either.

Not impressed. Sorry I wasted MY time.

https://www.tcnatile.com/products-and-services/publications/218-english-publications/188-handbook/948-2017-tcna-handbook-for-ceramic-glass-and-stone-tile-installation.html Buy one. Internalize it. Start over planning with reality in mind.

Looks like I struck a nerve.

First, I'm not engineer, rather a liason Between engineering and wrenching so I get your point.

But what happened to this forum?

"Hire a pro" is not the answer I'm looking for in a diy forum.

I have incorporated the input provided.

The slope is 1/4" and seems to drain well.

The shower walls and pan are sealed.

It may not work perfectly but it won't be catastrophic.

Relaxxxxxxxx.....

Read the TCNA handbook and start over. That is industry standard practices. Using below industr standard practices WILL lead to mold and rot. Guaranteed.

it's done. It took three and a half months.

It seems to work. No matter where I spray water in the stall none of it splashes past the knee wall and hte leg-shaving bench. and the deck drain catches all of it.

The membrane extends up the wall a foot or so and all the backer board it slathered in liquid membrane.

Time will tell on the waterproofing. But the design and materials is a big fat F. Did you just go to job sites and pick up the scrap $.49 tiles next to the dumpster?

Wow, are you like this in real life?

I was not seeking opinion on the design, but thanks.

An artist friend who gave me the tiles was sure we could come up with an eclectic but pleasing design but his health tanked and the design was shared by myself and another zealous helper who also faded away.

I certainly would have spent the money on a set of matching tiles if i were to do this again.

But the path for moisture is contained.

I'll let the tenants live with it and let my wife choose the tiles when we move back in.

Actually, I posted the photo thinking that when you saw the layout it might make more sense or you could provide more informed criticism.

I'm sorry if i devalued your professional input, that was not my intent.

I just re-read this whole thread and I'm just not seeing what the issue is.

There is more than the min amount of slope and a barrier in the shower. All water flows to the drain and little or none gets past it.

In the course of this project I ripped out tile i put down in 2008, it was bone dry after ten years of four children NEVER doing what i said regarding shower curtains and splashing in the tub.

So how much water has to sit on the tile and for how long before capillary action beats evaporation?

what is that thing that looks like a large cinderblock? a seat?

Sorry to tag on to the end of this thread, it's already a bit messy to say the least.

I have spent countless hours researching linear drains and am at my wits end! Bathroom floor is dropped by 1-5/8" from floorboards (2-7/8" below wood floor in adjacent room) in a 56-1/4" x 90" area ready for this project. I need to place the drain as a barrier by the entry way spanning the entire 90". Cannot go against back wall easily because of joist limitation.Tile will be sloped in from 14" outside of the shower including capilliary break then up to the back wall, drawing NOT to scale! I will have wedge wire grate and two 2" ABS outlets in to a 3" ABS drain, so not overly concerned about flooding the bathroom. I am aware of the 3" drop and wet room requirements. My main dilemma is how to terminate the linear at each side wall. I saw photos in another forum where the wall tile 'tabs' in to the drain channel, drain channel extends under wall tile at each end. In order to do this could the entire floor and drain be finished first with channel extended about 3/4" past the intended plane of the finished wall? Silicone caulk the drain at each end. Then the walls could be floated in and the tab cut on the bottom of the two opposite tiles that would sit in the channel. Floor will be hot mopped (I'm in California), walls lath and mortar, and the floor also floated outside of shower area. I'm on a wooden sub floor obviously. Finally, I have narrowed my options down to site sizable QM Delmar or the DERA-Line. Both have pros and cons, does anyone have any advice as in 'stay away from' or any pointers re these two drains? I realise the DERA is cheaper, 304 S/S as opposed to 316. The DERA is custom made to exact length rather than site sizable as in the QM or I may not even be asking the question about the walls. I'm leaning in the DERA direction because price is getting high and the wife is pushing to avoid linear, which would pain me after getting this close. The Dera is coming in around $1100 vs $1500. I thoroughly appreciate any advice or guidance anyone can give. Btw, i am not doing the job personally, just due diligence to be 100% certain nothing is compromised or overlooked. Thanks very much in advance.