And the rest . . . 
Once you have your entire perimeter done you simply need to pack deck mud into the rest of the base from the perimeter to the drain. Once again – beat the hell out of it. Seriously, pack it in there really well. The more dense your floor is the better. You need to ensure that the line of the floor is straight from the wall to the drain all the way around without any major humps or dips. It takes time and patience – use both. This step is critical since this is the substrate your tile will be installed upon.
Once you get the remainder of the deck mud packed into the shower and have it correctly packed and leveled just let it set for at least 12 hours, 24 would be better. Really, leave it alone. There is something about a freshly packed mud bed that makes people want to pick at it – it’s alluring – and a bit disturbing. But you need to leave it alone. So quit poking at it.
After it sets for about 12 hours you can fine tune it, so to speak, if you need to. Any un-flat spots can be scraped, rubbed, or sanded down to flatten them out. You can use regular sandpaper for this – really. Just make sure you have a flat surface from the wall to the drain. FLAT – not level. You want this surface absolutely flat.
If you have not yet done so you can now install your moisture barrier and backerboards. Now that you have a large waterproof box you are ready to install your tile and make it look all pretty. The hard part is finished. As with any proper tile installation the underlying substrates are the most important. Take your time with the preparation, it is imperative. Without proper preparation any tile installation is doomed to fail.
And your dog may burst into flames.
For detailed information about how to create your curb and tile substrate for it read this: Creating a curb for your shower.
Need More Information?
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.
Hi Roger,
I’ve got one last question for you about the mud deck. I am not happy with how it turned out, at all. Is it advisable to take it out, or just to patch it? I’m talking about patching the entire surface versus starting from scratch… but of course, I don’t want to end up puncturing the liner in the process. I’m really torn here.
Hi Kris,
I have absolutely no idea which mud deck you may be speaking of. If it’s a question you’ve previously asked you’ll need to post this as a reply to that question or answer as stated right above where you typed this. I have (literally) over 15,000 comments on this site, with about 50 new ones each day, I don’t memorize them all and I get a LOT of questions about mud decks.
Hi Roger, I was going to install a pre-formed shower pan and do liquid topical waterproofing on the walls and have bought “Liquid topical waterproofing for walls around a tub or pre-formed base”. Now I (mostly wife) want to do a traditional shower pan (the one with pvc membrane and deck mud) so it can be tiled and still do liquid topical waterproofing for walls. My question is in the transition from floor to wall: Can I treat the traditional pan as it were a pre-formed base and follow your instructions for that? The excess membrane would be like the lip of the pre-formed base with backerboard overlapping it with liquid topical waterproofing on that. Or is that crazy? If not, which manual or method do I need to accomplish this? Thanks
Hi Bryan,
That is exactly how you do it.
Roger, i’m planning to use kerdi membrane all through out my shower including the base and curb. what type of thinset use for the base floor tile and wall tile when using kerdi membrane?
Hi Bobby,
Unmodified.
Hi,
If I want to go the Redgard route I have read I need to go up the backer board a ways.
In your article you mention using plastic behind the backer board to prevent moisture damage to walls.
My question is what should happen at the bottom where the backer is coated on the front with Redgard and the back with plastic. It seems like any water that has got through the backer will be stuck.
Should I just Redgard the whole thing?
I really don’t want my dog to burst into flames…
Hi Jacob,
It will be stuck. You can not use traditional wall membranes (plastic) if you have redgard on the floor. You need to do topical on the walls when you have topical on the floor.
It seems like it would be nice to have the drywall on before my 2nd coat so that I could chalk a line for my finished level but then I’m concerned the drywall will deteriorate being underneath like that.
I am doing a 5×6 walk in shower as a remodel. There is already some drywall on the walls. Should I remove about 12″ of the drywall, do my preslope, liner, 2nd coat, then put the drywall back on? Or: remove 12″ of drywall, do preslope, then liner, then put drywall back on and do the 2nd coat? I’m using Kerdi on the walls. thanks Phil
Hi Philip,
You need to remove 12″ of the drywall. If you are using kerdi on the walls with a liner in the floor then you need to replace it with backerboard. You can’t have drywall over the liner unless you cover all sides of it with kerdi.
My new shower has a mud pan with liner. The very top below the tile(pebbles) is redgarded. Grout has not been applied yet but will be epoxy. Just learned from your writings that a “moisture sandwich has been created”. How can this be fixed. I am afraid that I will be fighting installer, builder and architect as well as drive my husband crazy if I bring this up. How big of a problem is this if ignored and is there anything that could be done other than pulling all the tiles up and remove the red hard.
Additional problem I noticed, is that there are void spaces underneath my floor and wall tiles, i.e. large areas where there is no thin set at all and I can also see Redgard between most of the tiles (still ungrouted). It looks to me that mortar was only applied to tiles and not to all flooring. If I use epoxy, will it disappear underneath the tile, become super expensive grouting job or cause caving in? What would be a proper fix for this?
Your advice is greatly appreciated.
Hi Elina,
It may be fine, it may not. I can’t guarantee a problem, I can only guarantee methods that will not cause problems.
At this point I would just leave it. Your installation will likely take more grout than normal. If it is grouted correctly it won’t cave it, buy you’ll use more grout.
Hi Roger,
We have finished the top mud bed. Everything looks good except I am afraid we should have made it 1/8″ thicker. We had thought that the thin set mortar would add some height beneath the tile. Is that true? When I line up the tile to the strainer of the drain, I’ll be about 1/8″ below the strainer. The top mud bed is completely set now and I cannot adjust the drain. Will the thin set mortar make up that distance or should I figure out a way to increase the thickness of the top mud bed?
Hi Liz,
If you use a 1/4″ x 1/4″ square notch trowel you’ll end up with 1/8″ layer of thinset beneath your tile.
Hello Roger.. Thanks for all the great information on your site. My friend down the street, who is also finishing his basement, told me about your site. I am looking at potentially doing an all Kerdi shower. Kerdi membrane on the wall, linear drain, and possibly the shower pan as well. I see that Kerdi makes a presloped shower pan for their linear drain made of extruded polystyrene with the membrane already attached to the base. Based on the information on the Schluter site, the compressive strength of the XPS is more than 2x what you can get @ Home Depot or Lowes. I just want to make sure this stuff isn’t too “soft” that it might give over time and the tiles crack. Would appreciate your thoughts.
Hi Scott,
Once tiled the compressive strength is more than enough for a shower floor. I’ve actually seen someone drive a forklift onto one of the tiled ramps – no joke. They work very well. I understand your apprehension, but believe me, they work well.
I am doing my first ever shower pan. The concrete floor underneath was level and perfectly clean before I started. I used Mortar (Portland, lime & sand) mix for the pre slope. When I set the mortar, I checked the edges for level and then sloped towards the drain. All looked good 24 hours ago. When I checked it this morning I discovered 2 issues:
The mortar has hairline cracks in it. Is that a problem? What should be done?
Also, when I checked the slope with the level from edges to drain, there are low areas, where it appears the mortar “settled”, leaving a void between it and the bottom of the level. Can I fill those areas to make the slope precise? What should I use to fill it?
What caused these issues and how will I avoid similar problems with the deck mud after I get the liner in?
Hi Diana,
You need to use deck mud to create your shower floor, mortar is simply too brittle and cracks too easily (as you’ve noticed) and there’s absolutely no accommodation for movement of any sort. The mortar needs to be removed, it will not work for your shower floor.
Roger; a couple of days ago i asked about coating the shower floor with “red guard” and you said ‘just a couple of inches out fro the wall’.
Why wouldn’t you want to coat the whole floor up to the drain (it has a liner under the mud bed) for extra protection?
Thanks Norm
Hi Norm,
1. Extra protection is not necessary when properly built.
2. It can create a ‘moisture sandwich’ with the top mud deck sandwiched between two impervious membranes where moisture can be trapped and mold can begin to grow.
3. Your weep holes will not function properly, they need to.
I finished my top slope and the curb on the pan. when I was done with the top slope its looked really good. now thats its dried completely (2 days later) I see that there are dips in about 8 spots after I rubbed my fingers across it and the sandy parts rubbed out. is there any way to fix the top slope or will the thinset make up for the dips under the tile?
Hi Josh,
The thinset will take care of it, but you can skim over it with thinset first, let that cure, then set your tile. Makes it much easier.
ROGER: I’m BUILDING A SHOWER, IT IS NOW READY FOR FLOOR TILE.
HARDYBOARD HAS RED GUARD ON IT. CAN I COAT THE FLOOR WITH RED GUARD ALSO? ( IT HAS A LINER UNDER THE MUD BED). THANKS NORM
Hi Norm,
You can paint it out onto the floor about 2″ or so from the walls if you want to, but you don’t want to cover the entire floor with it.
Hello- I’ve completed the pre-slope, have the liner in and the top mortar bed. Do you apply the thinset directly on to the mortar bed for the shower floor? With mortar being a bit “sandy” will the trowel dig up the mortar ?
thanks
Jim
Hi Jim,
Yes, it goes right to the mud deck. Unless you are REALLY digging in the trowel isn’t going to affect it.
Your article has helped me tremendously creating my pre-slope now I’m getting ready for the top layer but the problem I’m having is I’m not going to tile it, I’m going to paint the concrete for my finished floor and well I want the concrete smooth, any tips on how to do that?
Hi Nick,
I honestly have no idea how to do that so it would last. The deck mud would not be the product to do it with, though, it is not a wear layer.
Roger,
My mud pan went well, but to smooth it out and protect it while still working in the shower, I decided to use un-modified thinset over the cured deck as I read somewhere here you could do that. I will be using Kerdi.
So…I got it fairly smooth but there are a few ridges I just cant get out no matter how much I mess with it.
Can I sand the ridges and make it smooth after the thinset cures?
Thanks.
Hi Nick,
Yes you can.
My house was built in 2006, I want to rip out the plain white tile on the walls and floor and redo the shower. If I’m careful taking out the shower floor tiles can I reuse the shower floor instead of building a whole new concrete pan?
Hi Joshua,
Yes, provided they did not use a topical waterproofing membrane.
Would I be able to tell if they did when I take out the tile?
Yes, the waterproofing will be directly beneath the tile. If it feels or looks like cement you’re fine.
Hi Roger,
Thanks for the great site. I have built my tradition shower pan and was ready to tile when my wife came home with a different (thicker of course) floor tile. How can I rise the drain without destory my pan? I don’t want to affect the integrity of my waterproofing.
Hey Greg,
You should be able to unscrew the barrel of the drain to heighten it. If it’s stuck just work it back and forth a bit to loosen it up.
Thanx for great info!!!! —and fairly good jokes….Ha
Would you reccomend redguard on walls and in pan or do you have reservations about it’s use. Also if redguard is used on backer bd. it seems like the thinset would have a more difficult time adhereing to a slick waterproof surface.
Hi Bob,
I have absolutely no problem with redgard as a primary waterproofing for walls and floors. Redgard was chemically developed to allow portland crystals in the thinset to grow into the redgard, it will bond tenaciously.
Have you ever heard of using pea gravel as the first base of a shower floor?
Hi Don,
Yes, and it can be done provided the depth of the overall space is over five inches. It is used as filler.
Hi thank you very much for your articles. I have a questions about the hardie backer board used on showers wall. I don’t have many experience but I am doing my shower. I installed the boards up to 7′ where the old tile used to be. The wall up from that point is the old green board. I when to Home Depot and I got a wrong information about how to treat the joints. He said use a mesh or mash and gave a compound. After the application I realized that the compound was for dry wall. Do I need to remove it and do it again?
Second question, even thou the thickness of the hardie board match with the existing wall around the bathroom some places there is a 1/8 or so difference. How can the step can be fixed?
Thank you and hope hear from you.
Hi Paul,
Yes, it needs to be removed. The mesh tape needs to be embedded with thinset inside of the shower. You can either shim behind the lower areas or float out the difference with thinset to get everything flat.
A couple of questions as I am finding conflicting information everywhere about showers
I could swear that I read you have to immediately (undefined time) tile after pouring the mortar bed, or wait 28 days…I’d like to tile at about 48 hours, is that acceptable
Second, I listened to the part about not using mastic in my shower, but did anyway by accident as it said thinset mortar on the bucket. I did wonder how it wasn’t curing in the bucket…but did it anyway. Well, everything has redguard over it already except the foam bench, which is masticed (sp?) in place with the last of the bucket stuff. I would like to continue and redguard the bench, but now am worried about wetness making the mastic goey up through the mortar floor. Why can’t I just redguard the whole floor? making the entire inside of the shower waterproof?
Aargh, this makes me so irritated that it says thin set on the bucket….
Hi John,
You can wait 24 hours or 24 weeks, completely up to you. Not sure what you actually used the mastic (pre-mixed thinset) on? You can redgard the entire shower, but what do you have mastic under?
Thank you for the great article! Is there a certain amount of time after step 5 that you need to start putting tile on? I see in the article it states that you need to wait 12-24 hours but is there such a thing as waiting too long?
Hey Paul,
As long as you aren’t walking on it or stacking stuff on it the floor can sit there as long as you need. It’s just not a wear surface, it’s not meant to tolerate abrasion. If it’s just sitting there it’ll last forever.
Thanks Roger! I was worried there may be issues with settling while waiting for the Mrs. to settle on a tile color…shape…size…well, you know how that goes.
Cheers
Roger,
What is “Hot Mop” technique. I was told by a couple of people that this technique is best for showers on a concrete floor.
Hi Harvey,
Are you in California? That is about the only place in the country that uses it any more. It works, but is extremely outdated. It is a tar based coating used to waterproof your shower floor. And it needs a preslope as well (many don’t even do them correctly). There are MUCH better waterproofing products out there that don’t require the mess and a completely different company installing them.
Roger,
I want to put in a corner bench in my shower. I am also putting in a traditional shower pan. What stage should I be adding the bench and how should it be waterproofed? Can it be constructed out of wood or is block the way to go?
Hi Dave,
You can either build it before out of wood framing and backer, then waterproof it as you would the rest of the shower or build your pan and create the bench inside of it with blocks. Dealer’s choice.