I think if you are still in the sorta planning stages as you build that I would reconsider the half tiled walls at 48. If you live in a house with 8' ceilings you will be cutting the room exactly in half with the tile wainscot.

Its the same as getting dressed, you don't want to wear something that 'cuts you in half'.

I think you should consider 39" all the way around if you have a 33" high vanity or you could get away with 42" if you have a 36" vanity, since I am assuming the tile is acting as backsplash behind the sink.

What height should the knee wall be in the shower. It is a flanged tub on the 3 sides, so there needs to be a knee wall on one side of the tub.

The tub faucet/knobs tend to be somewhere around 24" from the floor, so the 36"- 42" would be adequate.

Do you have a separate shower? If not, how are you going to deal with the showerhead? it needs to come from somewhere.

The tub used to be in a 3 wall alcove (2 regular walls of the room, and one added alcove wall to the ceiling). We removed the alcove wall and want to replace with a knee wall to open up the room. The plumbing was moved to the full wall. The knee wall will be on the opposite end of the plumbing side.

The knee wall could actually be very low, just above the back of the tub, if you wanted to keep things very open. Are you using an L shaped shower curtain rod or doing glass?

Not sure about the glass or rod yet. I guess with either, the knee wall could be very low. Do you think I even need anything on the knee wall end? I saw a tub with just a panel near the plumbing end, which would be nice, but not sure if the bathroom would become a wet mess. I is a 2 foot glass panel that attaches to wall next to the plumbing.

You need to stop and address your budget What you're proposing is a LOT of work and money for very little gain. You will need some type of shower curtain (cheapest) or full height glass on top of the knee wall if you don't want a flood. You're also going to have to redo all of the rest of the walls to keep the installation watertight.

All in all, this is an ill conceived idea that will cost you many headaches to accomplish and won't give you very much return.

I lived in several rentals with 1920s bathrooms and two-wall tubs. They had shower curtain rods like this:
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I don't remember flooding the bathroom, and since they were 70 years old and intact, I don't think many other people flooded them either.

However, since I usually kept the shower curtain closed all the time, it didnt really add much to the overall feeling of space and light in the bathroom.

I have a bathroom with two full walls tiled to the ceiling with a hip height knee wall at the far end. I like the arrangement as it makes the bathroom feel larger than it would if I had closed the tub in with a wall on the third side, plus I don't happen to like glass shower doors.

I have a long, spacious tiled niche built into the knee wall on the tub side with a nice piece of marble as its bottom. I use it to store shampoos, raisors, etc. It's topped with a matching piece of marble with an ogee edge and on the side of the knee wall facing the bathroom is a nicely finished decorative panel above a base board that matches the one running around the room. The height is about chair rail height. We have gotten lots of compliments on it.

"very little gain"
"an ill conceived idea"
"headaches to accomplish"
"won't give you very much return"

How can this be...the 3 full wall alcove is so closed in and dark, the full wall cuts the room up. It is so more pleasing to have glass on the knee wall than a full wall.

Anyone have pictures?

Cutting down walls is expensive, especially if there are multiple stories involved and any could potentially be load bearing. Moving plumbing is VERY expensive---and sometimes impossible to do because it can't be vented properly in the new planned location. If you're lucky, you've got an accessible basement below and an empty attic above. If you're not lucky, it'll be completely impossible to do because you can't put the vent in the correct place or you'll have to jackhammer a slab. You'll have to completely redo all of the tub walls, get a new tub, and the glass will be $1K just by itself. You've just added thousands to the bathroom remodel if you DIY, plus huge headaches with the plumbing issues for a DIYer to solve. If you have to pay to have it done, it could easily add 10K+ to the remodel ticket.

I'm not arguing that it looks better and more open, but at what cost? That's the cost/benefit ratio you have to examine, and currently, the payback on expensive bath remodels is at it's lowest point in decades. Even if you can afford to put money into something simply because you'll enjoy it, how much enjoyment do you get out of creating the same exact bath, but simply in reverse? You haven't significantly affected the functionality of the room by making it larger. YOu've only done some optical illusion manipulation.

We are looking at doing about the same thing described, but live_wire_oak, you said something that worries me. We are going to be redoing the plumbing in our bathroom, and installing new pex plumbing. Right now the shower is a 3 wall plastic insert. They built a wall for the 3rd part of the insert.

We are removing that and replacing it with a knee wall.
On the back wall is were we are moving the plumbing to. The vanity and toilet are staying in the same position. Is there going to be vent issues I need to worry about?

Steph1, plan the space to accommodate the glass shower door option. If you build the space to non standard sizes, you will be forced to having a custom shower door enclosure. Custom glass is very expensive and time consuming, particularly when you are talking about knee walls. There are of the shelf products available, that provide heights and widths to build your shower spaces. Saves you tons of money.

Here is a link that might be useful: Dreamline Shower Doors

Although the kneewall is usually between 42-48" high, a house I just finished about a month ago, the GC wanted to make the kneewall shorter-- just something to end a full width bench. His thinking was it would give a more open feel to the shower being that it would be glass above, and quite frankly, I'm glad I wasn't able to talk him out if it. It looks great! This one is 30" high:

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