Coverting Tub Drain To Shower on Concrete Slab

kendog2March 5, 2009

We took out a bathtub and want to build a doorless shower in it's place. We have a concrete slab. We are wondering if it is best to move the drain to the center rather than leaving it close to the wall where it was placed for the tub. What parts are necessary to make the change? My DH is thinking of using a skill saw with a concrete blade to cut the concrete. Is there a standard placement required by code for the drain?

He plans to make the concrete floor sloped and do a tile floor. Will this require a membrane or can we skip it? DH is out of work right now so we need to do the work as inexpensively as possible. Any help would be much appreciated.

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Yes, you need a membrane...and a proper shower drain (with weep holes) to attach the membrane and then build a slope. And you also need a pre-slope underneath. It doesn't matter if it's centered or not, but it has to be done right or you'll have problems very soon.

    Bookmark   March 5, 2009 at 5:14PM
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lots of details still left out, let us know more about your house and slab in particular. E.g. is it post tensioned? And how much you might be cutting into it, or are you planning on building up instead of cutting into it?

Membraning can done many ways. One low-cost way is paint-on (trowel-on) liquid membranes; you can slap it onto any shape you build.

There is no advantage to moving the drain, but keep in mind how the tile - grout lines will fall, or break. E.g. if you plan for flat planes that slope to the drain.


    Bookmark   March 6, 2009 at 10:31AM
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Check out the John Bridge tile forum. It is a great resource for constructing DIY showers.

    Bookmark   March 6, 2009 at 11:15PM
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Thank you. I will check out the John Bridge tile forum. I don't believe the slab is post-tension. DH just got done moving the toilet 5" to make more room for the shower wall. He chiseled about a 12" hole in the concrete. With help from this forum it went very well. It sounds like a great idea to use the liquid membrane. What is it called and where can we purchase liquid membrane? If the liquid works well, I am wondering why anyone spends the time and money to use the Kerdi membrane?

Another question: DH is not happy with having the whole bathroom torn up. He wants to install the tile floor first and then work on the shower so he will feel a sense of accomplishment that part of the bathroom is finished. For several reasons, I think that the floor should be installed last.
1. We want the floor tile to go well with the shower tile. We haven't yet made a final choice on the tile for the shower. If the floor goes in first it may limit our choices for the shower tile. (We cannot afford to buy tile for both areas at the same time.)
2. We need to refinish (paint?)the vanity and wall cabinets. This work would be much easier to do while the floor is out.
3. Building a shower with a tiled floor seems like a messy job. DH plans to build a 5' tile wall. (The shower will be doorless.) I would think the process would be easier if we didn't have to worry about messing up the new floor.

Can anyone offer an opinion on whether it is important if the floor or shower is done first or is it just a matter of personal preference?

I will post photos later today that show the shower area with lines on the floor where DH plans to cut for the drain. Thank you again for your valuable opinions. I am so thankful to have found this site.

    Bookmark   March 7, 2009 at 9:22PM
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This photo shows the lines where DH is planning the cuts for the drain. Is this the right type of drain to use?

This photo is not mine. I copied it from somewhere on this forum. This is similar to what we want to do except that we have a 6 foot opening instead of a 5 foot opening.

    Bookmark   March 8, 2009 at 12:16AM
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kendog2, all your questions are good, and I would trust you to get the right answers, not overthink anything, and be good project manager. I'd buy anything you built, and I'd hire you to oversee a project I couldn't oversee. You are asking good questions with the right attitude.

Let me know what key words you use to search for liquid-applied rubbery waterproofing membranes like REDGARD or many others. Some membranes have other purposes, like e.g. to waterproof basement walls, so just keep that in mind when you search. There's a company called "Noble" that has a few products, one of them is like Redgard. I forget its name. Many others are out there; distribution is not coast to coast.

I especially like your ability to think for yourself when you said that installing Kerdi seems like more work than the easy task they make it out to be. At one world-famous web site, anyone who is a key player gets free product from the site sponsor (through a third party), and then gets recruited into dissing competitors' products. The sponsor company isn't doing the dirty work, it's done by volunteers. I'm sure you would spot that trend fast.

One product that makes perfectly flat tile-ready membraned walls is Wedi. Search and call them. You will still need to membrane the floor.

BTW, use a high quality drywall inthe bathroom, not greenboard.

Hope your husband gets his sights set on other goals. A floor could be one of the first things done but often isn't. No matter how much padding you put down afterwards to protect them. Also, tiles set with no grout in them can and do crack. However, I did one shower floor-first. It was not a problem.


    Bookmark   March 8, 2009 at 11:46AM
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Thank you David. DH does not always appreciate the "project manager" in me. He does a great job but could probably do without me second-guessing him. We will be using cement board in the shower, not green board.

I don't think I explained very clearly what I meant by "the floor". I was talking about the bathroom floor, not the shower floor. DH wants to install the bathroom floor before he does anything with the shower floor or walls. What would be the correct order to do this job? Is this right?

1. Move the drain.
2. Move the pipes and run along the back wall for the valve(s) We want to have a bench in the corner. We aren't sure if we should have two separate valves or use a Moen 3-function valve. We want to install a hand-held shower close to the bench. Should the pipes be wrapped since they will be on the outside wall? (We live in the high desert area of southern California. It does snow occasionally but we don't have below-freezing temperatures most of the time.)

It seems the easiest thing to do would be to place a 3-function valve near the shower head and run just one pipe to the hand-held. To avoid getting blasted by the cold water, we could set the valve to the hand held? Would this work very well or is it better to put the valve(s) near the entrance?

3. Run a 4x4 post to the ceiling where the wall will end.
4. Build the wall and curb.

Then what? Build the shower floor with slopes for the drain or finish and tile the walls?

5. Add vapor barrier?
6. Build corner bench or better bench?
7 Add cement board with niches or shelves for shampoo, etc.

Refinish the vanity and bathroom cabinets.
Install the bathroom floor last? Sorry for the multiple questions.

BTW We do plan to replace the peach toilet with a white one asap. Need to make sure we have enough $ to finish the shower first.

    Bookmark   March 8, 2009 at 5:46PM
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I started this post here because my first question was regarding the drain. Should I copy and paste my questions about the shower to the bathroom forum instead?

    Bookmark   March 8, 2009 at 5:52PM
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You will have a problem converting this tub to a shower.

Plumbing codes normally allow a 1 1/2" drain for a tub, but require a 2" minimum drain for a shower.

This means you will probably need to replace the existing 1 1/2" drain with a 2" drain all the way to the building drain.

Depending on the developed length of the drain, this can get quite complicated and expensive with slab construction, especially if you have a post-tension slab.

    Bookmark   March 8, 2009 at 8:39PM
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wow, lots of questions. In the first post and in the last one the same question is first.

You do not need to move the drain. If you devise a floor plan for your shower that slopes to the drain where it is, you will be fine. Consequences are that the wall-floor junction may have a slope in it, depending ...

Post a floor plan showing where the drain is now in your proposed shower space.

    Bookmark   March 8, 2009 at 10:22PM
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My husband prefers to re-locate the drain to make it look more professional. Today when he cut the pipe, he noticed that it is only 1 1/2" and wondered about the 2" code requirement. The pipes disappear into the wall. We certainly aren't willing to tear the whole house apart trying to convert to a 2" drain. The shower drain DH purchased is 1 1/2". We don't plan to get an inspection because it would cost a few hundred dollars we don't have. (DH is out of work right now.) Will a 1 1/2" drain work properly? Will we have to tear the shower out when we sell the house if the drain is 1 1/2" instead of 2" as required by code?

Here is a very rough (and not to scale) drawing showing the floor plan.

    Bookmark   March 9, 2009 at 2:56AM
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As was mentioned before, the first step in your project would be to convert the existing 1-1/2" drain to the code required 2" drain for a shower.

When considering the placement of the drain you must consider the total overall dimension of the shower enclosure.

Code requires that the shower stall must have a minimum slope of 1/4" per foot and a maximum slope of 1/2" per foot. Im addition, the finished elevation of the door threshold or curb MUST BE a minimum of 2" higher than the elevation of the finished drain opening.

At 1/4" per foot, in order to achieve a curbless shower you must have a minimum horizontal distance of 8' from the shower door to the drain opening.

Opting for a 1/2" per foot slope it could be done in 4', however it is generally considered that 1/2" per foot is a bit steep for safety.

    Bookmark   March 9, 2009 at 7:19AM
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leaving the drain where it is already, you may solve a lot of potential problems, and save yourself from extra work. Keeping the drain where it is today, you have the option to build a sloped floor that is for the most part a flat plane starting at the entry and going to the far end where a bench hides the drain. -- OTOH, moving the drain to the center gives you a standard inverted cone floor.

Your drain will still drain water with a 1.5" diameter pipe, if you leave it where it is today. Installing new pipe, increasing the diameter to 2", is the code. Code would also let you keep it at 1.5" if the shower area were a tub, i.e. with a ledge at the entrance to hold water in if the drain were stoppered or blocked. I know you may think this sounds a bit silly, that code does not permit showers to have 1.5" drains. BIG question to you, kendog2: How many feet is the distance from the drain today, to the stack? By moving it a couple feet, will that length be smaller or greater? This is important: if you exceed a certain length, the 1.5" pipe will not drain as well and you will not be satisfied. It could block up every time you use a shower and then dribble -drain itself very slowly. Seeing that you have not yet mentioned distance to stack, and based on your other questions since the beginning, I conclude you may be in for trouble no matter how good your analytical skills are. Don't move a drain if it means lengthening it beyond its carrying capacity. Don't let someone begin cutting concrete, until you know the consequences of the next few steps planned. Yes, there are showers that drain well through a 1.5" diameter drain, and mine is one of them. I paid a Master Plumber to install it, and I wanted a 2" pipe, and he used 1.5" pipe (long story).

A flat plane shower floor (sloped to one end) can be both easier to install than a four-plane inverted cone floor AND it can be seen as a high-end design feature. Many people would love to have a shower floor that did not have a visible drain in the center.

Before moving a drain you have to know whether that means lengthening or shortening the pipe that does to the stack.


    Bookmark   March 9, 2009 at 8:15AM
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Thank you. If I understand correctly, you are saying that if we leave the drain where it is now, we can keep the 1 1/2" drain without violating code? DH already cut off the little elbow at the end but I am sure he can attach another one. She shower will not be curbless. The curb will be at least 4" tall across a 22 to 24" opening. The rest will be completely enclosed on three sides with a 5' tile wall on the front side. We will add a 12" tall piece of glass to the 5' wall if the height is not sufficient to keep the water in. I don't think we would put a bench over the drain because it will be right under the shower head where one stands to take a shower.

It looks like the stack is less than 24" from the drain. However, we are convinced from what you said to keep the drain where it is as it would be farther from the stack if we moved the drain to the center. I agree - why create problems and more work for ourselves while adding the risk that it won't work after the work is done.

What is a good placement for the drain? How about 6" from the back wall so we can slope the floor away from the back and side walls? Should the top of the drain be installed flush with the concrete?

DH is also getting ready to cut the pipes to move the valves to the outside wall near the entrance. Does code require that he solder the copper pipe? Can he substitute with Copper Bond (Super Glue) instead of soldering? Thanks so much.

    Bookmark   March 9, 2009 at 7:54PM
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NO using the 1 1/" drain is NOT to code. Using super glue is NOT to code. Keeping the drain in the same location for a shower as it is for a tub is a BAD idea. Putting water supply pipes on an exterior wall is a BAD idea. NOt getting it inspected is a BAD idea. Not pulling permits is a BAD idea. Doing a project that can potentially really negatively affect your home's value if not done correctly or done shoddily is a BAD idea.

There is nothing wrong with DIYing a project if the DIYers skills are up to par and it's done correctly with the correct permits and inspections. This is VERY far from the case here. Shortcuts and safety skirtarounds abound in the ideas put forth. Codes and inspectons aren't there to make life difficult for people. On the contrary! They are there to make life safer for you and for the subsequent occupants of the home and represent the minimum level of safety that should be designed into a home.

The whole thing should be done correctly and to code or put back a tub/shower (correcty and to code) and be done with it.

    Bookmark   March 9, 2009 at 9:39PM
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It's a fascinating thread, with multiple dilemmas.

Here I am, an internet stranger, wondering whether to continue discussing the finer points
of a 1.5" diameter drain pipe left in place, as is, versus a new 2" diameter drain pipe from the stack.

Often one is one's own worst enemy.
The owner (or one of the owners) doesn't know
what post-tension means
and why it is serious (and could be dangerous)
what a stack is (or perhaps they do know this)
where their stack is
how far away it is
how easy it is to reach it and add a 2" pipe
so they resist

here are a few tips.

Hope they help:
Live_wire_oak said everything you "need to hear".
E.g. centering the drain in the middle of a floor is standard,
and placing it elsewhere -- if done by amateurs or half-qualifieds -- can make for an ugly shower.
Code does not say where a drain goes.

Lazypup said everything you need to know, and he did it in precise terms.
Not one extra word can be found in his text.
Not one word can be deleted; the words he wrote are all necessary.
Some topics he didn't cover: that has meaning too.

Whenever anyone tells me they learned a lot when remodeling,
-- I am certain that their house is not one to buy. Ever.

Whenever anyone tells me they bought a house that was remodeled by a previous owner,
-- I know that their next renovation will uncover surprises that cause anguish, anger and nightmares.


    Bookmark   March 10, 2009 at 1:53PM
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Thanks to everyone for their input. We sought advice here because we wanted to find out the best way to do this project. There is no way we want to do a shoddy job. If we didn't care about doing it right, we wouldn't have bothered to ask for help. We aren't afraid of doing extra work. We just wanted to make sure we understood how to do it before we attempted it.

We live in southern California. It does occasionally snow in our area but temperatures are seldom below freezing even at night. The shower head and water supply pipes are placed on an outside wall as the bathroom is bumped out from the rest of the house. This is the way the house was built so I believe it is to code for our area.

We have broken the concrete and attached a 2" tee. All joints will be soldered. (The last thing we need is a leak in a pipe that is encased in concrete with a new shower built over it.) We plan to wrap the pipes in foam that is designed to prevent pipes from freezing. My husband considered routing the new water lines through the ceiling but decided not to because he thinks it will be difficult to get around the window from the ceiling. We will also be moving the drain to the center of the shower. Here is a photo of what we have done so far. Does it look all right? Thanks.

    Bookmark   March 13, 2009 at 3:29AM
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The copper pipe at the bottom was punctured by the jackhammer. We weren't able to remove all of the water from the pipes in order to solder them. Instead, we fixed it with pex pipe and shark bite connections. I am a little nervous about whether a "plastic" pipe will last forever. Is it acceptable to cover this with concrete? (We will be wrapping it in foam and plastic before pouring concrete.) Thanks.

    Bookmark   March 14, 2009 at 7:56PM
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did you deburr the copper pipe before connecting the sharkbite?

    Bookmark   March 14, 2009 at 10:14PM
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Yes we did. Thanks.

    Bookmark   March 17, 2009 at 4:44PM
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I guess now would be a good time to point out that your choice of product is not wise, in the strictest sense, so i maintain what i said earlier, in the previous post.

    Bookmark   March 18, 2009 at 9:46AM
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We are progressing with our doorless shower. The wall is framed in. We have installed a Moen 3330 3-function transfer valve with a pipe extension for the hand-held slide bar. Please advise on whether this is the best placement for the valve and water supply. We're not sure if we should place the slide bar on stud #2 or #3 and where to put the water supply valve.

We plan to use the hand-held shower to shower our daughter who is disabled. She will be seated when I shower her. We need to decide whether to install a corner bench in the back near the #3 studs or use a portable bench in the center of the shower closer to the # 1 stud. If we do the corner bench and place the slide bar on the #3 studs, I wonder if I will get soaked by the water coming toward me. The black line shows where the bench would be.

If we go with the portable bench, we could place it in the center where the wall would stop the water from coming out. We could place the slide bar on the #2 stud so the water is flowing away from the doorway. In that case, should we move the valve a few inches to the left so the slide bar isn't as close to the valve? Would it look strange to have the power supply on one side of the valve and the slide bar on the other side?

Since we can't afford to purchase the hand-held and slide bar yet, I can't experiment to see how it would look and if the hose would hang properly. Any advice would be appreciated. The bottom photo shows the type of hand-held shower head that I am considering. (I like the way it extends out unlike others that seem to stand up

    Bookmark   April 27, 2009 at 2:47AM
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Can anyone offer any suggestions for the placement of the valve and water supply? Thanks.

    Bookmark   April 28, 2009 at 8:54PM
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