I am making a shower pan on concrete. The previous owners took out the bath tub and made a shower in its place but didn't use a membrane or anything. Needless to say we have tore it out and are replacing. My question is, since the drain is on one end of the shower how should I slope it without getting that "falling in" feeling? The shower will be 30x60 with the drain on the right not in the center. Any help is appreciated!!

The steepest slope is going to be at the end wall near the drain.
Not really an issue as you don't stand there. The floor needs to slope up at 1/4" per foot of run from the drain.
The goal is to have the top of the mud bed the same level all the way around the perimeter.

It's really no different than standing in a normal bathtub.

RC, am I correct in assuming that a Kerdi drain will probably not work in this situation? I have never tried it before, but I always thought the flange of the drain would be against the wall.

like RC said. take the longest run (drain to furthest wall corner)in feet and multiply by 1/4 inch. Set a level line at that height above the drain all around the perimeter. build your mortar bed to meet that line. so if your furthest corner is 4 feet from the drain you need to set your perimeter line 1 inch above the drain level.

This results in a variable slope with a 1/4 inch/foot minimum.

Kman, a Kerdi drain will work, but you need to do a extra skim coat work on top of the mud bed after to smooth out the transition on the steep side.

Jill would have to bust up the floor around the clamp drain to replace it with a Kerdi drain. If your going to do that, you might as well run it to the center.

thanks for the help everyone! We are hoping to do some mud work today but most likely it will be tomorrow. One more quick question, does it matter how many 2x4's I stack? Right now there are 3 but I'm thinking there should be one more. Also should the lath go down with the preslope or on top of the membrane? i've seen it both ways on the internet but will take your advice above all others. Thanks again!

3 or 4, doesn't really matter unless the final bed height finishes at the bottom of the 3rd 2x4

Are you talking about the lath over the curb?

No not the one over the curb but the one you put one the floor of the pan.

Hi Jill,

If you're doing a standard shower base over concrete the steps are a bit different than over wood. You can bond the pre-slope to the slab with thin set mortar, and so there is no need for lath on the floor. I suppose you are familiar with all the other steps?

I try to only do Kerdi shower these days. Much better then any other method. Go look at some pics of a Kerdi shower. The one over a slab shows the deck mud being bonded to the slab as you should. http://picasaweb.google.com/tile4youinc Also study the "Shower deck old method" sketch. That is how yours should be.

Jaz

Hi Jaz thanks for the advice! One more question, hopefully, do i need to let the thin set dry before I start the pre-slope or can I just do it in one step?

Thanks again to everyone for all your help!!

put the mortar bed directly on fresh slightly runny modified thinset. If it takes you a while to get going you may have to re-trowel the thinset periodically to keep it from skinning over.

Jill,

As Pete said the point of the thinset is to bond the deck mud to the concrete, so mud over fresh thinset.

If YOU or anyone else reading this has a question that needs further clarification, You may call my mobile at 248-670-3967. Don't worry, I have several thousand roll-over minutes that I should use up.

Jaz

Ok here's an update, we did the preslope on saturday and it went well. Thanks to all of you of course! Today tho I noticed that there was some sand on the top of my mud bed. I started sweeping and ended up with a pretty good pile of sand! Is this normal? If not what do I do now? ( Don't say tear it out and start over please!! )

We are eager to get started with the membrane phase but want to make sure this is going to be ok.

Thanks for all the help!!!


Jill

The pre-slope sounds fine, and it really doesn't matter that much anyway. So go ahead with the membrane. Are you going to fir-out the studs to allow for the thickness of the folded membrane, or what are your plans? What kind of backer are you using? How are you building the curb?

Jaz

Whew! I sure am glad to hear that! The membrane folding part was my next question. If we fir the studs then add the wonderboard how do i compensate for the difference to the original drywall outside the shower?

As far as the curb, we have 4 stacked 2x4s and are going to use metal lath over it.

Jill

Here are questions for the future of the shower building experiment:

Should we use a vapor barrier behind the cbu or just redguard it all?

Use white thinset, gray thinset, or mastic for the shower tiles?

We want to tile over the existing marble floor in the bathroom, will regular or modified thinset do the job or is there a better way?

I really want to thank you all for your help! You have no idea how much you've helped
out!!!

Jill

Harry has some very nice articles about this right here. Go to the home page and read away. http://www.ontariotile.com/

Shim about 1/4" use lattice or ?. You'll have an extra 1/4" of grout is all. If you can find "mud cap" (A4200) to match your tiles, you can shim out 1/2" and use the mud caps to return back to the wallboard.

Curb, 4 2x4's are ok. I use 3 but?

Surface membrane is much better than the other method. So use Redguard or Hydro Ban unless you go with Kerdi shower.

I would use white thinset. Do NOT say the "M" word around professional. It is no good for wet areas. And NEVER on floors.

Scuff up the marble with ruff paper if it's in perfect condition and no hairline cracks in the grout. Use white modified thinset just like in the shower. What tiles are you using anyway? Shower walls, floor and bath floor?

Jaz

white thinset is always used with marble, glass tile, and sometimes used with light colored grouts to avoid any chance of ghosting. everything else can be done with gray thinset.

If you are going to use Redgard, then you don't need cement board, just drywall.

if the walls are not load bearing you can notch out the studs to accommodate the liner folds. If you fur out 1/8 th or 1/4 you can run the tiles a little bit past the drywall transition and use a thicker Schluter tile edge.

Thanks Jaz and pistolpete! I didn't know you could use drywall and just redguard it I thought you had to use cbu. Lucky for us we have some greenboard in the garage now we can put to use.

We are using 12x12 tiles on everything I think. We've been talking about using bigger tile on the bathroom floor but haven't decided.

Well we are off on vacation starting tomorrow so no work will get accomplished until next weekend when we get back.

Thanks again and I will read those articles on the home page when I get back for sure!

Jill

the shower pan itself should be a 2x2 or smaller mosaic.

Hello all. Still at it on the shower, had some family things to attend to since. My question now is, we have the greenboard up in the shower so now do we tape the seams with thinset or regular drywall mud before we use the redguard? I have read to use thinset in the corners and the seams but the ones I've seen have been using wonderboard.

Are we going to regret using greenboard even with the redguard or will this last?

Thanks again



Jill

Personally, I don't like to use Redgard directly on drywall. It just doesn't seem to bond very well. Greenboard may be even worse, since it's got kind of a waxy coating on it.

Here's what I would do: Flat-trowel thinset over the whole thing, using alkali-resistant mesh tape at the seams and corners. Let that dry overnight, then use Redgard over that.

Yes you are going to regret using greenboard. For one, industry standards have virtually banned the use of greenboard in shower areas.
No liquid membrane can save you now. You will have to install a sheet type membrane like Kerdi or Noble Seal.

Do you have poly behind the greenboard?
The manufacturer specs don't allow vapor barriers behind greenboard.

Ok so we are going to put up something different now since we don't want to have to do this again! Besides wedi what is the best to use? Hardibacker or durock?

Either one is fine, however, if you are going to transition from CBU to regular drywall somewhere in there, Durock or Permabase is slightly thicker than hardibacker and makes the transition a little smoother.

RC, while there are no manufacturer's recommendations for this, some installers won't even put Kerdi or other sheet membranes on greenboard. They say the wax coating hinders the bond. I don't have knowledge of that myself, just what I hear.

Ok heres what we did. We put up HardBacker and used the hardibacker screws so now we tape the seams with thinset and the alkali tape then redguard right? There is no poly behind the backer board. Also do I use the mesh tape on the screw heads or just thinset?

You guys are the best!!

Tape on seams only.

Does it matter if i use gray thinset if we are using pearl gray grout?

Also do I need to get the special marble thinset for the floor tiles in the shower since they are marble or will regular gray thinset be ok? The walls of the shower are ceramic.

Quick question, how many coats of redgard should we use? We have lots left..

What colour is the marble?

RedGard says you only need two coats, but thats if you could apply it at its required mil thickness. You just have to make sure there are no pin holes after the second coat.

The marble is dark green. We will be sure to do a second coat but how long do we have to wait before we tile?

Overnight with redgard. Be a bit careful no to poke through it with tools while setting.

For green marble an epoxy based mortar should be used.

Okay I have two different answers for the thinset. One person- I forget who-said that since its only 2x2 tile that versabond would be okay and that there would be very little chance for warping since they are so small. Can someone either verify that or is epoxy the only way to go?

Also we did the curb today and it didnt really turn out as good as we had hoped. Its pretty ugly actually! It doesnt seem to want to hang on to the mesh. Did we not use enough water or what and will it be okay? Should i spray some water on it with a water bottle? hopefully all is well and tiling is next but we will wait for a reply from the pros-thats you guys! Thanks to all as usual!!

Jill

I have a question about my mortar bed. Since it has taken us so long to do the tiling the mortar bed has been walked on etc. etc. needless to say I can see the membrane. My questions are 1. how do i get up the rest of the mortar bed and 2. is there a way to fix it or just start over? Thanks

If you're able to, post a pic of the curb. We can tell you if it's fixable or needs to be torn out.

As for the mud bed, if you can see the liner, I'd say it needs to come out. How thick was it at the drain?

Jill,

How on earth can that be? The deck mud should have been about 1 1/2" or thicker. You're saying you walked it off? Why was it not covered with cardboard or ply? Never mind.

A picture would help. Either a link or by email.

Jaz

Well Jaz what happened was someone put a step stool in the shower and stood on it . It was covered with a moving blanket but the foot of the step stool poked a hole in the mud. Then I started to sweep

The mud is about 1/2 inch at the drain

OK, trying to remember what's going on without reading all this again.

You have a pre-slope right, and no problems. Then you installed the drain and membrane. You then installed a vapor barrier on the studs, the CBU or (?) on the walls. You then placed the mud deck, which is only 1/2" at the drain and it is now damaged? And the curb is not right?

OK, start over with new deck mud, then build the curb again. What type of mix did you use for the deck mud, and for the curb?

Jaz

Hi Jaz Yes we did everything like you said, the preslope is fine along with the waterproofing. As far as the curb goes, it didn't look pretty but I leveled it out with thinset and I think it's fine. My question is, since we have to redo the deck mud do we also have to redo the curb? We used mortar mix for the curb.

As far as the deck mud we used the calculator we found online that calls for 133lbs of sand topping mix and 67lbs. of coarse sand. Does that sound right to you? We are going to home depot today but will wait for your advice.

thanks again

I have been using Quikrete sand topping mix for several years, but the past few times I bought it there was a large amount of tiny gravel in it that made it hard to work with. I put up with it two times and decided that was enough.

I've started using TileCrete all the time now. If TileCrete or some equivalent is not available at your local tile store, I would suggest using 5 parts sand to 1 part portland cement. Be sure you add just enough water to hold it together, no more.

I would probably make the bed a little thicker than 1/2" at the drain if at all possible, maybe 3/4-1". Make sure you're able to screw the drain up high enough for that, also.

Thanks Kman we will look for the tilecrete but if we dont go with that and use the Quikrete do we use the formula i had posted?

Also what is the safest way to get the old mud out without damaging the membrane? I'm thinking plastic hammer and a shopvac but what do you think?

We will definitely make the bed thicker at the drain like you suggested.

Thanks again

Mixing deck mud is simple .... you use a few bags of "Sand-Mix" found at any building supply store and mix with very little water. Pack it well by pounding it hard, and then scrape it to the contours required.

Thanks Harry. Now I guess its time to get all the old mud out and start over!! Ugh!

Jill,

The optimum mix for deck mud is 5:1, for shower floors like yours it's 4:1, but anything from 3:1 to 6:1 will work. Quikrete Sand Topping is 3:1 and since it is "rich", it's a bit harder to work with. That is why some people suggest adding sand to adjust the ratio. I have done dozens of shower floors without the addition of sand.

The problem with adding sand and that calculator is that people forget that the ration is given in volume, NOT weight. So, 4 shovels of sand to 1 shovel of Portland. I think most people are adding too much sand. Not sure I haven't calculated the density of sand to Portland by volume yet.

I just finished a Kerdi shower, I mixed 240lb. of sand mix and added some sand I had. Not sure how much, but not more than 40-50 lbs. It's not that critical, just do not add too much.

You may be able to separate the deck from the curb? Be careful, use a wide chisel and tap lightly.

Had you consulted with me......I would have suggested a Kerdi shower though. Much better!

Jaz

Hey Jaz

I think you're right about the sand, I think we used too much and made it weak. I think that might make it easier to get out though and not wreck the curb!!

In hindsight we would use the Kerdi if we were to do it all over again (not including this redo of the mud deck!) Moving the drain and breaking up concrete doesn't sound to awful hard right about now!

Thanks for all your help Jaz and everyone. Might not get to do much more til after Thanksgiving but will start for sure by the weekend.

Hi Jill, I don't know if your question about small green marble tiles got answered or not. In theory, any size can curl with exposure to a non-epoxy mortar, but practically speaking a 2x2 tile likely will not.

We did a floor this past summer and I gambled and used regular thinset-but the tiles were very small and I was certain there wouldn't be any perceptible warpage.

Happy Holidays everyone! Here is a rundown and a couple questions. We tore out and replace the mud deck which came out great! We have done the tile on the shower floor and the walls. Now my question, we are using Mapei grout and I'm wondering if we use it for the shower floor do we have to wait 21 days for it to fully cure before we seal the grout and use the shower? I have read about waiting 72 hrs. but I am confused.

All help is appreciated!

Jill

As far as sealing, check the directions on the bottle. Most of the ones I have used require 48-72 hours before sealing, then 24 hours before using the shower.

Merry Christmas & Happy Holidays to you Jill and everyone reading this.

Kevin's got you covered on the sealer. The correct time to wait is whatever it says on the bottle.

Congrats on completing your shower. Since you built a pre-slope under the membrane, your shower is probably built better than 99% of the showers in our fair State of Michigan. Well, that goes for most any part of North America too.

Jaz

Too bad we never got any pictures of a completed job. We rarely work with 4-1 or 5-1 hand mixed deck mud anymore. I have found that the product from Mapei their Mapecem Fast Setting Screed Mortar is just to good not to use it.

Regular deck mud has no "Ad-Mix" or extra additives to make it stronger. The Mapecem is easy to mix since it mixes wetter than regular deck mud and dries in hours and not days.

Worth looking up if it's available to you locally.

Over concrete it can be feathered from 1/4" to 4". With the thinner lifts a slurry coat is need by mixing one part Mapecem with one part Planicrete AC.



Grading layout for large barrier free bathroom



Grading with the Mapecem is about twice as fats as 4-1.



Better to use a Magnesisum float - sticks a little to the redwood or wood floats.

JW