The following five-part series gives a basic overview of building a shower floor for tile. If you would like a complete step-by-step of the entire process with all the little idiosyncrasies and details I now have manuals describing the complete process for you from bare wall studs all the way up to a completely waterproof shower substrate for your tile.
If you are tiling your walls and floor you can find that one here: Waterproof shower floor and wall manual.
If you have a tub or pre-formed shower base and are only tiling the walls you can find that one here: Waterproof shower walls manual.
Curb and Pre-slope
Properly built shower
There are a couple of options to create a shower floor for tile using deck mud. The first is a single-layer shower floor which can then be coated with RedGard or a similar product or covered with kerdi to waterproof it. The other is a normal shower floor with a liner which will have two layers – a preslope, the liner, then the top slope which is then tiled. This series of posts will describe the latter.
Before we start I should note that unless you are using the kerdi waterproofing method or utilizing a liquid membrane as your floor liner you should not have the backerboard installed in the bottom part of the shower. Your waterproof membrane for a shower floor will be installed behind your backerboard. The curb and pre-slope need to be completed before installing the lower wall substrate.
Creating the curb for a wooden floor
The first thing you must do is create the outside curb of your shower. You need to create the “box” which will become the inside of your shower floor. Depending upon whether your shower will be created on a wood or concrete floor will dictate what material you use for your curb.
If you have a wooden floor you want to use regular dimensional lumber. The 2 x 4’s they carry at Home Depot – those. That is the easiest and most readily available material. Ideally you want to use kiln-dried lumber. That is lumber that is, well, dried in a kiln. By removing moisture in this manner the moisture content of KD lumber is normally between six and eight percent compared to regular dimensional lumber at close to 15%. Why does that matter? Well moisture and wood don’t mix. As it dries wood has a tendency to warp and twist. The less moisture initially in the wood the better. KD lumber is best and regular air-dried dimensional lumber is also acceptable. NEVER use pressure treated lumber – ever.
I usually use three or more stacked 2 x 4’s to create my curb depending on the size of the shower. Simply screw the first one to the floor (with correct non-corrosive screws), stack the next one on top and screw it down, and so on until the desired height is reached. That easy.
Creating the curb for a concrete floor
Using Bricks for a shower cub
For a concrete floor you want to use bricks. Yeah, bricks. Just stack ’em. I use gray concrete bricks (no holes) and stack them two or three high for my curbs. You can use just regular thinset to adhere them to the floor and to each other. Just stack them in the shape you want.
You do not want to use wood for your curb on concrete. Wood will actually absorb moisture from your concrete and start to swell.
Creating the pre-slope
This is one of the steps most often skipped by a lot of people – amateurs as well as professionals. It is imperative! You need it – it’s that simple. Without a pre-slope your waterproof liner will lay flat on the floor. This does not give water anywhere to go. It will sit there, stagnate, mold, . . . you get the idea. With a proper pre-slope any water will drain to the weep holes in the drain and go where it needs to – away.
Lathe installation for wood floor
You need to first make sure your shower floor will stay where you put it. On wood you can use regular metal lathe.
You need to place what is called a ‘cleavage’ membrane beneath your lathe. This is just a sheet of plastic or tar paper stapled to your wood floor first with the lathe placed over it. The membrane does not make anything waterproof! If someone tells you that hit ’em in the head with a bat. It is necessary to prevent the wooden floor from sucking the moisture out of the pre-slope prematurely causing it to cure too fast (or not fully) and significantly weakening it.
When your membrane is down staple the lathe over the top of that. Just cut it to the shape of your shower floor and lay it flat on the floor and staple or nail it down. This gives your mud bed something to grab onto. In the above photo I have used plastic as my membrane and only have a partial piece of lathe in – make sure you cover the entire area below your pre-slope.
A properly prepared pre-slope
For a concrete floor you need to mix up some regular thinset except you need to mix it “loose”. That just means you need to add a bit more water than the instructions call for to make it thinner. Cover your shower floor area with this before you start installing your deck mud. The deck mud itself does not “stick” to anything, you need to supply something that will adhere it to your substrate.
Oh crap – Math???
To make the installation easier you’ll want to mark your height lines on your wall studs. To figure out how high it needs to be off the floor you need to figure out your slope. This involves a bit of math – don’t panic! It’s easy. Figure out which corner is farthest from the center of your drain. Your slope needs to go up in height 1/4″ for every foot. If your furthest corner is three feet from your drain center your slope needs to rise 3/4″. Easy enough so far, right?
Your finished floor (after your liner and top mud bed are installed) needs to be 1″ to 1 1/4″ thick at the drain. So, if we make the pre-slope 3/4″ thick at the drain it needs to be a total of 1 1/2 inch thick at all your walls. So mark a line 1 1/2″ from the floor all the way around the wall studs. This will be the height of your pre-slope at the walls. I try to make my pre-slope the correct thickness at the drain so it will be 1 1/2″ at the walls. This way you do not need to draw lines, just level your perimeter with the top of the 2 x 4 studs along the bottom of the wall. Depending on the size of the shower it doesn’t always work, but it saves time if you can work it out that way.
If your shower is not a square, and they rarely are, you still need to have the same thickness at the walls all the way around the perimeter. This means that you will have a steeper slope on the walls closer to the drain. This is normal. If you don’t do it this way you will have uneven tile cuts at the bottom of your wall. By doing it this way you will ensure a level line and, in turn, a level floor around your perimeter.
The height of your pre-slope at the drain can vary. It needs to be level with the top of the bottom flange of your drain. Regular drains have two flanges which bolt to each other. The pre-slope needs to be at least level or a touch higher than the bottom flange. Your liner then goes between the top and bottom flange to utilize the weep holes in the drain. This allows any water atop the liner to drain. The pre-slope supports the liner so it needs to be level or above every point of the lower flange. Does that make sense?
This is why planning is so important. Your drain needs to be high (or low) enough and your curb needs to be higher than your shower floor – naturally. So figure all this out before you build anything.
Playing with mud
Now we need to mix up a batch of deck mud. Check out that link, I’ll wait . . .
Okay, once your mud is mixed up you want to start packing it in there. If you are going over concrete and have your thinset slurry down, cover the entire bottom of the shower floor first to ensure the entire base will stick. If you have a large shower only spread as much thinset as you can reach over at a time. Start at the walls and pack your mud down really well – beat the hell out of it. Seriously, beat it like the last DMV employee you spoke with. You want to eliminate any voids and create as dense a bed as possible. Don’t worry, it won’t hit back.
Pack it down around the perimeter to just above your line. When you get that done get yourself a 2 x 4 about 18 – 24 inches long. Lay that on top of your mud bed against your wall and tap the 2 x 4 down with your hammer until it is even with your line. This ensures a level, even line all the way around your perimeter. Perfect! Now don’t touch the edges.
Properly prepared deck mud
Continue to pack mud into your shower base all the way from the perimeter down to the drain. You should have a straight line from the perimeter to the drain without any dips or humps. This will allow water to drain correctly without pooling anywhere. While this particular layer of your shower floor does not have to be exact, you do need to make certain it is fairly flat in regards to the line from the perimeter to the drain.
Ensure a consistent slope
That’s it. When you get it all packed in there it should have a shape similar to a very, very shallow bowl. Now leave it alone. Really, leave it alone. The next day it will be ready to install your liner and all that fun stuff. Don’t play with it until then.
In my next post I will show you how to install your waterproof liner. Until then leave your pre-slope alone. It’s fine. Quit trying to perfect it. We’ll do that tomorrow. Get away from it. Really. Stop staring at it . . .
Read this next if I haven’t already bored you to death: How to create a shower floor Part 2
Awesome site, thanks Roger for all the suggestions, tips and humor. I’m buying your book just
Question regarding the shower drains. I’ve seen a few people embed the drain into the sub-floor, so the top of the “lower” section is flush with the surface of the sub-floor. They then pre-slope from the drain (0″) to the wall (3/4″), then liner, top mud, etc as normal.
Most manufacturers don’t even mention doing this, even though the drains have angled edges.
Thoughts one way or another?
Thanks.
Hey Jason,
You’ll have a stronger installation if it sits above the subfloor. Deck mud is not really stable enough to feather to a 0 base, it’ll end up cracking right around that drain about six inches out. At a minimum of 1/4″ (1/2″ is better) it will stay in one piece.
Okay, we got the preslope down over the weekend. We put down the dry pack around the perimeter (the perimeter is flat and level) first then worked down toward the drain. Somehow, we can’t make it evenly slope down toward the drain. Could you please tell me how it make it evenly slope down toward the drain?
Thanks,
Monica
Hey Monica,
Get a 2×4 and cut it the length of the space between your perimeter and drain. Overfill the center in that space then use the 2×4 to screed off the excess to a flat plane.
Sooo…. 1st timers here…..We want to tile a shower in our basement & need to create the floor. It is a cement floor with 3 walls that are studded. Do we need to do the brick all the around the shower to create the floor as well as the curb? Also, our Drain has about a 12″ opening around it….does this need to be filled in prior to doing any work on the floor? Help! and Thanks!
eagerly awaiting your reply (eating popcorn and drinking beer until we get it! )
Well…..you know sometimes the forest for the trees??? Think we figured out the base part all by ourselves…..miracle of miracles! Build the waterproof walls first & then just have the curb in the opening…Some Days
….. That only leaves the ? about the drain. Will the roof felt be enough support there or should we fill in that void?
You still need to fill it in.
Hi Lisa,
No need to bricks around the perimeter. Just for the curb. The opening does need to be filled, but you can fill it with deck mud as you create the shower floor.
Roger,
Regarding preslope, since the distance between the center of the drain to one end of the wall is 60″, our preslope would be 1 1/4″ around all the perimeter. Is this mean that we also need to slope at 1 1/4″ on top of the liner? Together, our finished shower floor would be 2 1/2″ above the rest of floor in our bathroom.
We also took out our 2×4 that we already put in and replaced with brick and set it with Mapei Ultraflex 2 thinset. We mixed it with water really well before we applied it to both brick and slab. After it was all done, we found out that we should let the thinset sit for 10 minutes and then re-mixed it 2 minutes. Is this going to create a problem since we used it right away? Also, how long do I have to wait for the brick to fully set to the slab (the bag stated it takes 16 to 24 hours) before we can work on our pre slope?
Thanks in advance.
Monica
You can make your top slope 3/4″ thick. Your top slope will be a consistent thickness, they pre-slope already has the required slope, the top slope simply follows it.
You can work on your preslope in about 12 hours. It will be set enough at that point.
Hello Roger,
How do you come up with a total of 1 1/2 inch thick at all your walls under “Oh crap – Math???” with 3/4″ pre slope and 1″ to 1 1/4″ thick of finished floor? If I do 3/4″ preslope plus 1″ thick of finished floor, I come up with 1 3/4″ at the walls. I might missing something here.
In term of preslope, once you pack the mud down really well at the walls, how do you make it an even slope down to the drain? Would using a level work?
I think this finished up all my questions about pre slope.
Thanks,
Monica
Hey Monica,
The 1 1/2″ thick is only for the preslope (or the entire slope if using a topical membrane). I try to do that simply because it comes out even with the top of the footing plates, which are normally 2 x 4’s.
A level or straight-edge will create your slope from the walls to the drain.
Roger,
We had a guy came in to do a preslope for our shower area on the ground floor. Our two storey house is sitting on the concrete slab, not basement. He used a wet cloth to wet the concrete slab before putting down the Sand Topping Mix that mixed with water only, no additional sand. Would this bond since he didn’t use thin set? If not, what would happen later on?
Thanks,
Monica
Hey Monica,
It won’t bond to the concrete but it doesn’t need to. You simply have an unbonded mud deck. It’s just another method, it’s fine.
Thanks Roger,
Okay, I checked the preslope last night and found out that lots of areas weren’t sloped correctly. It ranges between 1/4″ to 1″ off. (It is an odd dimension shower, 48 in. x 72 in. with the drain that is 12″ from one end and 60 in. from the other end as we didn’t want to re-do the pipe.) Can I just put down more Sand Topping Mix plus sand plus water on top of what he already put down (sand topping mix plus water) with a thin set bonding? Or would it be much easier to take out the whole thing and start over again? If so, how to take it out since I have done this before?
Just curious, if it is fine to have unbound mud deck. Then why bonded it in the first place?
Thanks,
Monica
Please disregard this post as we’ve taken our incorrected preslope out and re-do it correctly.
Okay. Please disregard my answer to your previous question as I answer them in the order in which they were received (without the teeth-grinding hold muzak…)
You can wet down the existing mud deck, sprinkle dry thinset (powder) onto the area then add the new mud.
A bonded mud deck is a more stable installation. That, however, is most true for very large mud decks, like 150 square feet large. On smaller decks there is no discernible difference.
Howdy,
I used your recipe for my pre-slope and slope. Thanks, it was great. But now, I’m at a loss for the curb. did you use the same mix/deck mud for a curb? I tried to do it with some metal lathe and it just crumbled. What do you suggest? More water to the mix? add lime?
Thanks for the help and the site!
Welp,
Looks like I found it. I need to make up some Fat Mud. Just like the Deck Mud, but adding 1 part Lime.
Deck Mud:
4 Parts sand
1 Part Portland Cement
Fat Mud:
4 Parts sand
1 Part Portland Cement
1 Part Lime (for zest/twang I suppose lol)
Thanks again for all the help!
You got it.
Hey Mason,
For wet mud (the stuff for the curb) you need to add 1/2 – 1 part lime to the mix.
Hi Roger…I’ve noticed no one seems to like the idea of putting 1/2″ Hardiebacker down for the shower floor…why is that? If I build up the corners with floor mud isn’t that the same thing as building a deck mud preslope? Is it if the rubber pan leaks then I’ll be sorry? Thx for the info.
Hi John,
Backerboard has no give to compensate for movement inherent to shower surfaces. Deck mud has a lot of sand in it which dissipates movement before it reaches the tile surface.
Hi Roger,
I just made my shower curb using Quikrete mason mix and it looks beutiful. But of corse part of it is pitched the wrong way and is out of level by about 1/4″. Can I mix up some more mason mix slap it on top and pitch it correctly or make it up with the thinset when I put the top plate on? Or do I have to rip it out and start over?
Thanks,
Hey Sam,
You can mix up more and install it. Wet the top of the curb down before you install the new stuff.
Roger,
My preslope was off a little bit in the corners, then I scraped a little much in another area (I know you said not to). Anyway, I moistened the areas, mixed up some more deck mud, then smacked it good with the float and screed it out.
I later noticed you have mentioned using a bonding agent, like a thinset slurry, before adding more mud. I did not do that. The mud I added was less than 1/4 inch and only in a couple of small areas (the entire shower is only 54×28). Am I in big trouble?
Hey Pat,
Nope, you’re fine. Spray down the areas you replaced one more time just to add more moisture into the process. Water is utilized to grow crystals in the portland, the longer it stays wet the longer and stronger the crystals will grow. Since you wet down those areas it should be fine, if you spray it down again you’ll have nothing to worry about.
This project is at my mom’s house 40 miles away — but i had her mist it twice last night and again this morning, so hopefully that will do it. Thank you for getting back with me. I feel a lot better moving forward and driving in tomorrow to put in the liner. I will be much more careful with the final pour this weekend. Thanks again.
Best website for shower renovation. This website is the only one that spells things out in sensible format, gives clear options, and no nonsense, straight forward advice (with some hilarious snarkiness). Thanks for sharing your expertise. Questions are certain to follow soon since I am nearly done with the demolition phase.
Hi Roger,
Have you considered having your own network DIY program? I am using your liquid membrane publication (love it!) to convert a poorly consructed garden tub area to a walk in shower. Before I found your site I had contacted RedGuard to ask if their product would be utilized the same way a PVC liner would be used(placed between the pre-slope and the final mud deck), they told me that it was necessary to have the final mud deck on top of the RedGuard before the tile installation. Your divot method would certainly save time and makes perfect sense to me. Do you know why they would want to risk the integrity of the RedGuard base by working mud on top of it? Also, I am using PVC drain(due to cost)so do I need to use embedded mesh at base of divot?
Thank You Very Much,
Sherri (A Sadly Displaced Colorado Native)
Hi Sherri,
Using redgard in lieu of a pvc liner is an acceptable, approved method. It also saves them from attempting to explain to people how to do a divot, and from the liability of that.
It’s simply easier to say ‘yes, in lieu of the liner’. With three or four coats on the mud it’s actually fairly sturdy and you can work mud over it.
Yes, you should use embedded mesh at the base of the divot for redgard.
Why in the world did you leave Colorado??? Did you live in Boulder and vote republican, or something crazy like that?
Help!!!
I am building a custom shower pan using a topical liquid membrane. The pan is in the basement on concrete. I was advised to put down thinset before making the pan out of deck mud. I did as instructed, but of course, no one mentioned the thinset needs to be wet!
Do I need to rip this out and redo? I don’t understand, I mean, over plywood the deck mud floats on the roofing felt. In a typical shower pan, the deck mud floats on the pvc liner.
So do I really need to rip out the pan?
Thank you so much.
Dan
Hey Dan,
Nope, you simply have an unbonded mud deck rather than a bonded mud deck. For the purposes of your basement bathroom it makes no difference whatsoever.
Roger,
Thank you for your reply. I wish I had bought your book before starting my project. I’ve been relying on a tile site and while I have gotten much good advice, a lot of it was conflicting. Shortly before your reply I decided to rip out the deck mud bed and redo it. So mine is now bonded, but I’m not surprised it makes little difference in a basement bath.
Thank you.
Roger, please help. I bought the Mark E. Industries pre-pitch and quick pitch system since i am a newbie and was worried about getting the pitch right. Mark told me it was fine to use Durock under this instead of lathe. So i have the wood subfloor and then Durock put down properly with thinset and then screwed every 8 inches. Then I did the pre-pitch with deck mud. It worked fine. I think the only reason NOT to do this is that it is more expensive than putting down lathe and tar paper. Is there any other reason??? Please let me know your thoughts.
Hi Janice,
No reason at all. It’s simply another method to accomplish the same thing. There are many.
Hi,
I am wanting to pour a concrete shower pan in a space measuring 31 1/2 by 33 1/4. I wanted it not to have a curb and continue the tile from the floor of the shower right out into the rest of the bathroom. I was told that the slope in a space that small would be to steep to stand in and I would need a curb either way since the bathroom is very tiny 60 inches long by 33 1/4 inches wide. I would appreciate any advice you can give me.
Rose
Hi Rose,
Why would the slope be any more than a regular shower??? Any slope to a drain needs to be 1/4″ per foot. Whether your shower is two feet wide or twenty feet wide the slope is the same.
With a bathroom that small the entire bathroom floor should be sloped from the entry to the drain. If you indeed want a flat surface the entire thing needs to be waterproofed and properly sloped. And the slope will not be more or less than any other properly sloped shower floor.
Thanks Roger! I appreciate your help!
Your instructions are marvelous, having people like you giving advice makes all the difference in the world! I hope you can help me out.
I have a shower that is already installed in my house, the floors and walls are made of concrete (well the walls aren’t cast, obviously, so I’m thinking they were made with some applied mortar on cement board), and they were finished with paint and a glossy epoxy. The problem is the epoxy is now all abraded on the floor of the shower where the water regularly drips. So I was thinking about installing tiles on the floor and wall.
My question is: do I need to reinstall a waterproofing membrane or can I install the tile directly on the cement floor? Should I first sand off the epoxy?
The slope is also not ideal so I was thinking about installing a row of cement bricks to make the curbe (thanks for that, I was really wondering how to do that part), and then redoing part of the slope with cement (well, now ‘deck mud’) and then installing mosaic tiles.
Suggestions?
Thanks!
Actually I just read the comments below mine and it seems like a similar situation, it aswers most of my questions. I’m just not sure about the epoxy finish, should I sand it down first? Thanks!
Actually I just read this question after I answered the last one.
Yes, you should sand it down first.
Hi Myriam,
I don’t understand how that shower is supposed to be waterproofed as it is currently built, unless the epoxy paint is supposed to be your waterproofing. If so, and it’s abraded off due to dripping water, it isn’t a very good one, eh?
You can install a curb and fix your slope with deck mud and tile. You do, however, need to do a bit of work to get the shower waterproofed correctly. The easiest would likely be to remove the epoxy coating (most bonding materials will not adhere to cured epoxy) then install your curb and fix your slope, then coat the entire inside of the shower with redgard or Hydroban. Any elastomeric liquid waterproofing will work – those are the two best, in my opinion. Once that’s cured you can tile directly to it.
Thanks a bizillion!
Wow! That’s a lot. You are welcome – a bazillion minus 12 bucks – I’m gettin’ a six-pack.
Very helpful site! Wished I had discovered it before starting my job
I am adding a basement shower. The walls are concrete and a bit uneven so I installed backer board up for a smooth tiling surface. I did this step right and consistent with your instructions. However, the problem is I did this before installing a pre slope and waterproof liner on the concrete floor. So now I don’t have any way to get the liner behind the backer board. I installed the backer board with liquid nails and screws onto the concrete walls so don’t think I can remove (at least easily).
What would you suggest?
Hey Marty,
You can use a topical liquid membrane in place of your liner. With a product like redgard or hydroban you can create your preslope, paint on your membrane (it is a different (thicker) layer thickness than on walls – check the instructions) on the floor and up the wall, then install a top mud deck and tile away. The liquid membrane works just like your liner.
Thanks Roger. I will give that a try. By the way, your website continues to impress me. Nice work.
Forgot one clarifying question. Since I have a concrete floor, I was going to use bricks for the curb. Should I still use a membrane over the bricks so any water runs down the membrane and onto the redgard which is applied to the floor and lower walls?
Yes, the liquid goes anywhere a normal membrane would go – curb included.
Roger, sorry for so many questions. You’ve been really helpful. So for the curb, I basically build with brick adhering to the floor with thinset. Then I cover with deck mud and topical liquid membrane?
For the floor, I apply thinset down and then just build one sloped floor using deck mud and then cover with topical liquid membrane. My question is how do I deal with the weep holes if I don’t to a preslope? Or do I still do a preslope then topical membrane and then finish off with more deck mud on top.
The curb is just brick bonded to the floor with thinset and covered with redgard – no need for deck mud on it.
If you want to change the drain you can do a single layer with a topical drain. When you initially described what you have the solution I provided was with the double layer of deck mud with a layer of redgard in lieu of the membrane. This is an approved method by both the TCNA and Customs (manufacturer of redgard). It is simply a different use of the product. The weep holes are treated the same as with a traditional liner – the redgard is painted onto the pre-slope, clamped between the upper and lower flanges, then the top mud deck is installed and tiled over it.
I have a question. You said not to be use pressure treated lumber when you create “box”. Any suggestions when you are dealing with a bathroom remodel where you have three exisiting walls on slab on grade with pressure treated sill plate? Can you explain why pressure treated lumber is not a good idea when you create “box”? Thank you.
Hi Andy,
Pressure treated lumber can dry out and warp or crack when it does. It that is beneath a tile installation it will do the same to your tile. Over concrete you should build your curb out of bricks rather than wood.
hey, a question about that brick curb on a concrete floor.
the shower liner must cover it entirely. and, tiles dont stick to a plastic liner.
so the question is,, how to complete this brick curb?
thanks for the time.
The liner is run up and over the bricks then a piece of metal lath shaped like a ‘U’ is placed over it to hold the liner in place. Wet mud is then installed to the lath, then tile bonded directly to that.
just like the wood one. ok. cool.
but how come tiles cannot be set right onto the bricks. is that much water actually seeping thru grout lines, solid concrete bricks and thru a concrete floor. i can see for a wood home but a concrete highrise…seems overly safe.
at any rate, thanx for the info
Tile can be set directly to the bricks if you’re not concerned with having a waterproof shower. While the liner waterproofs the entire floor it must run up the sides around the entire perimeter or you may as well forego the liner entirely. A swimming pool will not contain water if it’s missing one side.
The concrete substrate will not be affected by water – it’s concrete. But it WILL absorb water. Think about a driveway when it rains – it darkens because the concrete soaks in water. While some may evaporate from the surface the greatest portion of it is pulled beneath the concrete by gravity and soaks into the ground beneath it. What’s beneath your shower?
And what is beneath it is not the only concern. An improperly waterproofed shower will allow water into the wall cavity. Even if the studs are metal – they’ll rust. And you’ll never see it until there’s a problem. If you do not contain the water in the shower with a properly installed liner and direct all the water into the drain the water WILL find somewhere else to go. Anywhere but the drain is going to cause problems in one form or another. Take a look at my ‘flawed’ page for examples of what can happen. I tear these things out weekly.
But yeah – you can set the tile right onto the bricks.
nicely written and helpful articles, elvin friend
I guess the thinset on a concrete floor is fully cured/solid/dry prior to the deck mud application — or not?
“Cover your shower floor area with this before you start installing your deck mud. The deck mud itself does not “stick” to anything, you need to supply something that will adhere it to your substrate.”
Nope, the deck mud is installed over it before it cures in order to bond it to the concrete.
Roger,
Our shower is on the second floor. The previous shower was one of those fiberglass inserts. The sub floor underneath it has a very large hole cut out around the drain. Picture an oval cut out of the sub floor about the size of a football while the drain pipe is about the size of a baseball.
I am presuming the sub floor will need to go right up to the edge of the drain pipe, otherwise the deck mud will not have anything to sit on. They don’t make levitating deck mud do they?
Ever run into that? What do you think is the best way to fix that? I was thinking of putting another layer of sub floor on top of the existing sub floor and put the deck mud on top of that. Think that will work, or is there a better solution?
I guess I could also cut out part of the sub floor and make the football shape a square that has edges on the joists and just cut a square piece to match that newly-made hole.
Thanks again for your help.
Rob
Hey Rob,
No levitating mud decks of which I am aware. Sure would make hauling the mud upstairs much easier, though.
Cut a 1/2″ of plywood big enough to cover that hole by about six inches all the way around, drill out your baseball and just set it right over the hole. Screw it down and install your mud right over it. It doesn’t need to be level or flat beneath your deck mud – that’s what the deck mud is for.
Or, you can cut the square out, cut a piece to fit…you know, the hard way like you’ve described.
Thanks Roger. I also bought your liquid membrane waterproofing guide. Great stuff.
Two more questions for you.
First, if my subfloor is 1/2″ higher around the drain due to covering the football sized hole, does my deck mud floor have to be 1″ thick on top of the extra 1/2″ already there? Then, if I am 2 feet away to my farthest corner, the height of that deck mud would be 2″ thick correct (1.5″ for the normal slope plus an extra 1/2″ to make up for the “step” in the middle around the drain)?
Second, using the liquid membrane method, does my cement board go all the way to the floor (minus a 1/16″ space for movement)? I think it does and then my deck mud floor would rest up against the cement board, correct?
Thanks again for all of your help,
Rob
Hey Rob,
If you are using the topical method with a single layer mud deck then yes, you need to have the extra 1/2″ in there around the drain. Your height measurements are correct.
Yes, the backer will go nearly to the floor with the deck mud right against it.
Hi there,
I’m considering building a 3′ x 5′ shower in a mod home. I’m a little concerned about the weight on the structure. Is there anything to consider with the weight of the shower base exceeding the floor joist capacity? Do they sometimes need to be reinforced?
Cheers!
-Frank
Hey Frank,
Yes, sometimes they do need to be reinforced. If you have 16″ oc joists beneath the shower you should be fine. If it bounces when you hop on it you should probably reinforce it.
I have a mobile home that my customer wants a shower in He is a tall man and I only have 7 foot from floor to ceiling. can you tell me anyway I can do this without a shower bed? Thanks
Mike
Hey Mike,
Sure, use a pre-fabricated acrylic shower base. If he wants tile he needs a mud deck. In normal structural housing it is possible to lower the joists and rebuild the structural system beneath the shower to support a deck which will be flush with the bathroom floor. That can not be done in a mobile home without getting into some serious structural issues. The pre-fab is about the only option.
Or a skylight.
Hi Roger,
I just ripped out a nearly 50 year old basement shower I built when I was still a 26 year old newbie. The base tray was formed out of high density, nicely sloping concrete a tad steeper than the quarter inch, poured directly onto the basement concrete floor. My arms still hurt from separating one from the other and there was certainly never a leak. The pan was tiled with the tile GLUED down! Never leaked either. Couldn’t get them off so I removed the entire pan. The simple brass floor drain was embedded in the high density concrete, no leaks there either. What finally went after all this time was the tiled walls, no concrete wallboard, no Schluter products…
At the time, the shower drain was roughed in by the builder and left rising out of the finished basement floor by about 6 inches, capped with a piece of sheet copper.
Given this presentation of the original rough in, I would today conclude that a trap was installed at the connection to the waste water plumbing (inaccessible under the concrete floor slab of the basement). Anyhow as a newbie at the time, I went and tore up the concrete floor at the rough in stub and installed a copper pipe trap. Ever since, now and then, the water would pool in the shower until my size 12 foot would stomp on the drain to release a big air bubble more that likely hiding in a double trapped pipe.
So, the big question, since I’ve also removed the existing drain and trap and have a fairly sized hole in the original basement floor to centre the drain in the new bigger shower, do you have an (inexpensive) idea about how to test the drain for that (hopefully existing under the concrete basement floor) trap a good 8+ feet downstream from the shower drain? I am getting kind of tired of stomping on the drain for all and sundry users of the shower…
Thanks,
Peter
Hi Peter,
THAT would be a question for a plumber. Mine’s on speed-dial. Mine’s on speed dial because I have absolutely no idea how to go about that – he does. He’s a plumber.
I’m a tile guy. Sorry.
Try asking the fine folks over here: Terry Love’s plumbing forum If they don’t have an answer – there isn’t one.
Thanks Roger, will do. A couple of minutes ago I had a rare flash of intelligence breaking through. Went to look at where the drain was likely to connect to the waste stack. It’s under the basement stairs inside a still open sidewall. Found a copper vent pipe coming out of the floor connected to the main vent stack. Sure looks like viable evidence for trap venting. Will think some more…seems that some of the brain cells are still active!
Peter
I have that every now and then too! Not nearly as much as my wife wants me to, but nevertheless…
I would think that a copper pipe running to (or used to run to – now near) the stack would indicate proper venting. But it tells you nothing about what may be down in clogging or blocking the vent.
Hi Roger,
Love your site. Finally… someone that makes sense. Problem is, now I know I have a problem. Contractors have just completed the framing of my new shower (on a concrete floor) but it’s all framed with pressure treated lumber. Does the whole thing have to be ripped out? Can I coat it all with Red Guard or will this just make matters worse? HELP!
Hey Denise,
Actually your shower framing is fine with pt lumber. The only place it won’t be is with the curb – it should be built with bricks. The framing has wall cavities and areas other than the back of the tile to move – the curb has only the back of the tile. You’re fine (other than believing that I make sense
).
Hi Roger,
I am creating a neo-angle shower pan with Redgard and I am having trouble finding info about how the backer board should overlap. The only clue I have found so far is what you wrote above:
“…unless you are using the kerdi waterproofing method or utilizing a liquid membrane as your floor liner you should not have the backerboard installed in the bottom part of the shower.”
This leads me to believe that I can put my cement boards for the wall and the curb in before I do the pre-slope. Then after the pre-slope, I can Redgard with fiberglass mesh reinforcement at all change of planes and joints and corners, running the Redgard along the bottom of the shower and straight up the walls. If that is the case, my only concern is whether I need any additional reinforcement on the curb edges.
Everything I have seen so far shows the PVC liner, but with the neo-angle (\_/) curb I can’t figure out how to do it without cutting the liner, so I decided to do everything in Redgard.
Waiting patiently, with Beer of course, for your reply. Thanks, Dave
Hey Dave,
You complete the entire substrate – walls and floor, first then you install the redgard over the entire structure utilizing mesh reinforcement at all changes of plane – around the drain as well as every corner of the curb as well. You do not ‘lap’ your wall in any manner. The ‘topical’ membrane goes over the face of it all in one uniform layer – hence the name ‘topical’.
Your shower floor is only one single layer of deck mud – not two with redgard between. Completely different method.