To create a shower floor from scratch we use what is commonly referred to as “dry pack mortar” or deck mud. Deck mud contains three ingredients: regular portland cement, sand, and water. That’s it. Don’t let anyone tell you that a latex additive or anything else is necessary. It is not. Properly mixing and installing deck mud will create a shower floor that will last for years and years.
The ratio is very important to achieve the correct consistency and stability. You want 5 parts sand to 1 part cement. Your ratio can vary from 4 to 6 : 1 but the 5 : 1 is what I use and find to be the easiest to work. You want just enough water to dampen the mixture. It’s not a lot. Too much water will cause your mud to shrink as it cures and compromise the stability of your base. You just want it damp – really.
The easiest and most convenient way to get your mixture correct is to buy the quikrete “sand and topping” mix which is sold at all the big home centers. This is already mixed at a 3 : 1 ratio. For a 60lb. bag you need only add 30lbs. of sand to it. This is how I mix mine – it’s convenient. The easiest way to mix it is with a regular shovel or garden hoe in a mixing box or regular wheelbarrow, although you can mix it with and in anything that works for you.
After it’s mixed it should just be damp. When you pick up a handful of it you should be able to squeeze it without water dripping from it. It should be able to hold it’s shape when you squeeze it, just like a snowball.
Whether you mix the entire batch from scratch or use the sand and topping mix it should all have this same consistency. If it is any wetter it will shrink as it dries and it will not be as solid and stable as it should be. I usually start with about 1/2 gallon of water and work up from there. I think. I really can’t tell you exactly how much water to use because I don’t measure it. I’ll have to do that and include it here.
As you install and shape your base, slopes, and shower floors you want to pound the mix with a wooden or magnesium float. I mean beat the hell out of it. You want the mud packed very well with no voids. The harder you pack it the more stable it will be. I have or will have individual posts to instruct you how to shape shower floors, etc. This one is strictly to describe the proper recipe for your mix.
A couple of companies also make a mix specifically for shower floors and mud beds. I’ve only used one and it worked quite well. Just follow the mixing instructions on the bag and start with the minimum amount of water they suggest and work up from there.
When set (about 24 hours) the mud bed will be a perfectly suitable substrate for your tile installation. It will be sandy on the top. You can scratch it with your fingernail – stop doing that! It’s normal. I understand it’s counter-intuitive, but it really is normal.
Although you may have been led to believe that creating a shower floor from scratch is a very difficult thing to do, it is not. With careful planning and attention to detail you can create a shower that will last for years without any problems. Getting your mud mix correct is at the core of the proper method.
Hi Roger,
Well, this probably doesn’t qualify as snarky, but I have a 10.5 cu ft. quantity of pp-fiber screed to mix for a bath and trying to decide whether to rent a 5 cu ft mortar mixer and mix 3-4 loads, or get a mixing tub and use the paddle mixer and and end up with more loads. Either way I’m going to have to schlep buckets of the mix to the bath. About 1200 lbs of mix. What would you do? Hey, thanks a lot and keep up the great work.
Hi Kevin,
I would get one of these: bucket mortar mixer. It’s worth every penny. Since you have to haul buckets anyway you can use that and mix it right next to where you’re installing it. I mix up the dry ingredients in buckets and mix them right there in the bathroom.
Roger,
Thanks- I saw those things and they look well designed. I think I’ll run to Lowes or HD tomorrow and see if I can find a poly tub that will accommodate 1 full batch and use one of those mixers in the bath.
Given a 2″ bed thickness, I’m even wondering if the fiber ad-mix is even necessary- opinion?
I don’t use the admix for anything.
Guys,
I’m doing a 6′ x 5′ x 2 1/2″ shower floor, using your recommended 5:1 ratio, how many bags of sand topping mix & sand will I need ?
Thanks,
Bob.
Hi Bob,
You need about 10 80lb. bags of s&t mix and five 50lb. bags of sand.
Hi, I was building a small shower pan and messed up the deck mud mix. I used one 60lb. bag of sand topping mix and one 50lb. bag of play sand. The shower pan is 36×30 and some parts seem like they are not solid and the top is very sandy. Should i redo it with the proper ratio or will it be all right? Your help is appreciated.Thanks
Hi JP,
While a 6.3 : 1 ratio (What you currently have) can be used for your deck, it needs to be pounded and formed correctly to remain solid. If you have areas that don’t seem solid then they likely are not. I would remove it and do it with a proper ratio, which is much easier to work with.
how much mud will i need for a 46×27 shower floor 2 1/2 inches thick with a 5 parts sand to 1 part portland cement how many bags of each
Hi Dwayne,
Four bags of cement, two bags of sand. If by ‘bags of each’ you mean sand and topping mix and sand.
I love your site and leaned a lot, but I made a mistake and need your advise. I am redoing my shower stall from scratch using a “goof proof kit.” My problem is that in my haste to mix the first layer of mud for the base, I grabbed a bag of mortar (with polymer) instead of portland cement. I mixed it in about a 1-4-5 ratio and spread it out. It spread out fine, but I didn’t realize I used the wrong bag till I went to clean up.
Should I leave it, or rip it out and start over? I will be putting a 40mil shower liner on top of it and then more mud (mixed with portland cement this time!).
Please advise.
Chris
Hi Chris,
While obviously not ideal
it should be fine as your preslope provided it’s nice and solid.
Hi Roger,
Can you help a sista out! Yes I’m a girlie but I have ripped out toilets and sinks, replaced them, done the plumbing and tile so therefore thought tearing out this lumpy tile shower that pools water, doesn’t drain etc, etc in a house I bought would be fairly easily tackled….so wrong!
So here is what I’m dealing with. The guy who built the house must have been a boozer (nothing against that) just maybe not great when doing tile work. Tile issues everywhere. So, I’ve ripped up the old tile and the top layer of deck mud. Now I’m left with the pre-slope (if you can call it that) It’s got some rolling spots that I’m hoping you will tell me will be ok once I do the top deck mud application. I will be going over a black vinyl liner. Can I use your deck mud recipe and go directly on top of the liner. It will need to be about 1.5 inches. I was told NOT to do redguard as you NEVER want to have a membrane that close to another one as it may cause water to trap with nowhere to go. What-a-ya say to that? Do I really need another water proof application? Can I just use silicone where I’m re-doing the threshold with cement board and tile? It was never done right and had rotten wood, water damage, actually leaking through walls. I know, what a hack! I have been told I certainly cannot do this right and need to hire a pro but I’m no quitter, plus I live in Montana and don’t really trust that I can find anyone to do a better job.
I will greatly appreciate your advice. I’ve been pondering, reading and trying to figure this out for a few weeks now. You’re the only one that has mentioned beating the hell out of the deck mud which makes perfectly good sense. Looking forward to that.
Thanks-A-Mil
PS, sorry, one more question…once the deck mudd is set with the sandy surface if I don’t redguard do I do my thinset and lay tile or should I do an initial thin skim of thinset, let it cure then do my thinset and tile application?
Hi Reecie,
Provided the liner does not leak then yes, you can go right over it with deck mud. I do not have any idea what you mean by ‘can I just use silicone where I’m redoing the threshold’. Do you mean the curb? Because if so, then no. The liner needs to be wrapped up and over the curb (that’s what waterproofs it) then mud is formed over that, tile bonded directly to it. If that’s not what you’re talking about then you need to let me know. You do not want to use redgard over it, you need the traditional liner (what you have now) or a topical (redgard) – one or the other, never both. Once the deck mud is set you can either bond tile directly to it or skim-coat it if you want. Either works just fine.
Hi i took out an old metal shower in my basement and will be putting in a neo angle tile shower. The plumber came in and redid the drain. Seems he only left me about a 1/4″ lip from the concrete to the top of the drain. Will this cause a problem with my pre-slope. I will be putting down thinset to adhere the deck mud to the concrete floor. Since the edge by the drain will will only be 1/4″ should i use a latex additive in the deck mud rather than just water to make the deck mud more stable. In order to make the the pre-slope level around the wall, I was thinking about putting in a 1/4″ piece of wood around the wall and curb if order to use it as a gauge/screed to make the slope (instead of marking a line). Is this a bad idea. thanks
Hey Bob,
The 1/4″ at the drain will be just fine for the pre-slope. The 1/4″ piece of wood is just fine.
Hi Floor Elf –
Again great website – I keep coming back to it anytime I run into a issue on my shower remodel.
Im following your pdf on building a shower – Topical – Liquid – With backboard – I plan on doing the shower floor with pre-slope of deck mud with liquid (RedGard)
I just built the shower curb using quikrete deck mud following the mixing directions- removed the form 24 hours later and it has been siting 2 days – it seems solid – kind of sandy and flacky though. Couple of questions if you have time
What are your thoughts on Quikcrete Deck Mud?
Is that normal to be sandy and flakey?
Should I put thinset on top and let it sit before tiling or just use redgard on top of it then tile?
Thanks for any help – appreciate it.
Charley
Hi Charley,
Quickrete deck mud is good stuff. Yes, it will be sandy and flaky. It is easier to skim-coat it with thinset, let it cure, then redgard it.
Roger – thanks for the advice on the deck mud curb – next step I am going to put down the pre-slope using quikrete deck mud – any thoughts on how long that should cure before going to the next step of painting on the redguard?
Thanks Again
Charley
Hi Charley,
You need to wait three days before redgard installation on deck mud. I know it sucks, but more beer drinking time.
Hi Roger,
I am buiding a 32″x32″ shower pan on a concrete slab. Can I use deck mud about 0.5″ thick for a pre-slope? It will be covered by a PVC liner and another layer of deck mud about 1-1/4″ – 1-1/2″ thick. I’m just curious whether the pre-slope would be stable enough (perhaps I should use S type mortar?)
Thank you
Victor
Hi Victor,
Yes, you can. Yes it will be stable enough. No, do not use type s mortar.
Hi Roger,
I really appreciate the great resource you provide through your website.
It’s fantastic. I wish I found it earlier in my project.
This past weekend, I attempted my preslope mud bed for my shower remodel I’m attempting by myself. Where I am in the spectrum of handiness, I’m not sure. I’m certainly not the most handy of the weekend warrior handymen, but I like to think I’m not completely worthless. But, we’ll see.
Anyway, from your site and another online resource, I found the recipe for
the 5:1 deck mud. So, I bought a 60lb bag of quickrete sand topping mix,
and added half a 50lb bag of sand. I thought I had the mix just wet
enough, but maybe it was too dry (I added just over 3 quarts of water). Or
maybe I worked on the bed too long. It looked good when I was done though. The perimeter was level, and it sloped nicely down to the drain.
The next day the bed appeared sandy; but it kinda looked crumbly too.
There was one noticable spot that was a little high. On another site, I
read you could sand down high spots. So, i started with sand paper and
then onto a sanding screen. The dark brown look that it was (and I see in
most photos online) changed to a grey concrete type look. As I worked
around, I noticed some low points too (where it looks like flakes had
popped out). so, I ended up “sanding” the whole area.
The area is now generally smooth, but the texture is bumpy. There are
still a few small, shallow divots. Is this still good enough to put the
pan membrane on top of? Or does it need some fixing (thinset)? Or should
I chisel it out of there and start over?
https://plus.google.com/photos/100989272976998882362/albums/5939865502243979057?authkey=CKeuv6zc2sHnag
I will gladly buy you a hot chocolate tomorrow for some advice today.
Sincerely,
Keith
Hi Keith,
It’s fine the way it is, you can go ahead and put the liner over it. With your top mud deck pound it harder – beat the hell out of it.
I stumbled across you blog while researching deck mud mixes and here is my concern. We are installing precast pavers (20″ x 20″ x 2″) around a pool and spa. Apparently code requires the pavers to be bonded to the deck within 4 feet of the pool/spa perimeter. The thickness of our mortar bed will average 4-7/8″ and we intend to use a 4″ WWM for reinforcement. The mortar bed will be installed directly over 4″ Dow Plazamate insulation (60 PSI)/drainage composite/120 mils fabric reinforced CFA waterproofing. The 1/8″ joints between the pavers will be grouted upon completion. Have you had any experience with similar installations over insulation board? My concerns have mostly to do with cracking of the mortar bed as it bridges adjacent sheets of the insulation, and that movement being transferred up through the narrow grout joints. The only provision that currently exists for expansion/contraction is a caulk joint around the perimeter of the pool/spa coping. Thoughts or suggestion would be appreciated.
Hi ‘concerned’,
Deck mud mix is blended in order to dissipate movement from below the deck to the tile lamination, that’s why there is so much sand in it. The transference of movement or shifts is dissipated throughout the mud bed before it reaches the surface. I’m not familiar with the particular insulated board you are speaking of, but I am very familiar with deck mud. One of the reasons for the 1 1/4″ minimum in larger floor installations is to give it the depth to dissipate considerable movement from the substrate before reaching the surface. With almost five inches it is no concern at all.
Elf,
So I poured my final deck mud yesterday an I feel it came out pretty good. I will have to do some fine tuning in a few small places. Here’s my question (s), can I do the minor filling with deck mud in some of these areas if need be just like the pre-slope?. Secondly, I did not pour the curb because I wanted to focus on the shower floor and get it right. Can you give me an idea for the mixture just for the curb?.
1 concern I have is that once I got the floor all done I removed the drain and I noticed some deck mud got into the the weepholes. I used a plastic weephole protector that I bought with the Goof Proof Shower kit. I know these should be clear but how oncerned should I be about this?.
Thanks Roger
Hey Scott,
Wet mud mix is 4 parts sand, 1 part cement, 1/2 part masonry lime.
As long as they aren’t completely jammed full of mud they’ll be fine.
Thanks Roger. If need be can I fine tune spots in the final shower pan with regular deck mud if I find any?. With thinset between of course…
Hey Scott,
If they are less than 1/2″ or so you can just float them out with thinset. If they are larger than that then yes, thinset with more deck mud.
I now have a perfect deck mud shower floor (5×8) ready to apply kerdi waterproofing membrane to. The problem is the whole thing is a half inch too low. What product can i put over deck mud to raise it up a half inch?
Hi Ed,
Thinset and 1/2″ layer of deck mud.
Roger,
Thanks. I thought a 1/2″ deck mud would be too weak.
Bought your Schluter Kerdi waterproofing for shower base and walls eBook. Good info.
Ed
1/2″ layer of deck mud over deck mud it just fine. Use thinset between the layers so the top bonds to the bottom.
What would you allow for thinset, kerdi, thinset, total height wise?
I will be using pebble tile
Hi Ed,
5/16″ – 3/8″ typically.
Roger,
You said
“1/2″ layer of deck mud over deck mud it just fine. Use thinset between the layers so the top bonds to the bottom”
What would be the minimum height of deck mud over deck mud you could use in this way?
Thanks
You can feather it down to about 1/4″ or so, the balance can be skim-floated with thinset.
Hello, my girlfriend and I are tiling a portion of our house with 6×24 wood plank porcelain tiles. After a couple of days we realize that we can only do it in sections ourselves since we both work full time. My question is can we grout in sections and come back and grout the next section? I understand that grout must be mixed precisely the same every time to achieve color consistency, and it is black grout next to dark brown tiles so will we see much of a difference in the newer areas? I am posting pics in the upload site now.
Hey Todd,
Provided you know how the grout must be mixed it should be fine. If you blend the new in with the old (run the new grout line over the old about a foot and wash it all the way over when cleaning) you shouldn’t notice any difference at all.
I have just enough knowledge about tile shower floor installation to be dangerous. Broke my hand so I had to hire someone to take over for me. He tore most of the old shower out, but his start on the re-installation was disturbing enough for me to ask him to stop. First, he decided to reuse the old membrane (including nail holes from previous use) because “it was already well attached to the drain”. Then he poured self-leveling product onto the membrane, but it was not quite enough to cover the entire space so he plans to pour another layer over that, repeatedly saying this was the product he planned to use to build up the whole shower base. When I questioned the lack of anything under the membrane, he said he used PL adhesive under the membrane to adhere it to the subfloor. When I questioned the use of self-leveling product he said now he would use a high polymer concrete after he gets the floor level. When I asked about creating a slope to the drain, he said he planned to do it in the mortar layer as he lays the tiles. I haven’t seen any of this done in my limited experience nor do I find it anywhere in online sites or from the store I bought my tile. He tells me he’s done this dozens of times on much more expensive homes than mine and that he’ll stand behind his work but only if he does it his way. Should I have end his part in this project here and tear it back to the subfloor to start over or accept there is more than one legitimate way to do this and stay out of the bathroom?
Hi Suke,
EVERYTHING about what he is doing is incorrect. No pre-slope, reusing the liner (really???), slc for a shower floor…I just can’t comprehend how anyone would think that’s proper. And the old ‘I’ve done it this way….’ is my BIGGEST pet peeve with hacks who have no idea what they’re doing.
Get rid of him. He obviously is not interested in doing it correctly, don’t let him ruin your home due to his lack of knowledge.
Great information. Thank you so much for sharing it.
Hello to all,
I’m doing a complete bathroom reno in a 1954 house. The original floor was concrete slab, 1.5″ deck mud, 1.5″ (looked like mortar to me but maybe it was also mud) with embedded copper pipe for radiant heat followed by ceramic mosaic tile. My intention is to put it back with either a 1.5″ layer of concrete followed by a 1.5″ layer of mud with new pex tubing for the heat and finishing with new tile. The room is about 40 sq ft. is this a reasonable way to go about getting my floor back up to the necessary height and preserve my radiant heat? the old one stayed intact for nearly 60 years…gutted the room due to water leaks from other sources. thanks!!
oops…sorry. I didn’t complete the thought (so much for proofreading) my thought is to either do the 1st layer in concrete followed by tubing/mud/tile…OR to do a layer of mud followed by the tubing/mud/tile.
Hi Scott,
I would do 3″ of deck mud, but the concrete in the lower half will work as well.
Thanks so much…I decided to take your advice for 3 reasons. An all mud floor will be a 1 step install so to speak rather than doing 2 different substrates; it will be a little cheaper to do all mud; and lastly, my radiant heat lines come thru the wall at the vanity just above the mud layer so rather than bury the lines, I’m going to add 2 small hot water baseboard units…again cheaper and it keeps my plumbing accessible. Thanks again!
Elfman,
Finally getting back to my shower and need advice on quantities. My pan is 42″X 45″and I am using lathe and screening up to 1 1/2″. I bought your books but I can’t find anything that says how much mud to mix. I am mixing the Portland and sand myself as here is no premix around.
Thanks
Hey Chris,
About 25 lbs. of Portland cement and 125 lbs. of sand.
Worked like a charm. Thankee. Next up is kerdi on the pan and redgard on the walls. Can I use “Fibatape” in the wall corners (which have been siliconed) to bed the redgard? I have both flavors; alkali resistant and regular sheetrock type. Thats all I could find in these parts.
Also, I should have enough kerdi leftover to use it in my niche, instead of the redgard. I siliconed all the niche seams, just in case. Did I mess up? Will the thinset still adhere to the silicone or should I now redgard the niche?
Hey Chris,
Yes, you can use the fibatape. The thinset will not bond to the silicone, but it doesn’t need to, kerdi will still work just fine. I actually prefer using liquid membranes on my niches when given the option, it’s faster and easier. You can use whichever you want, either will work just fine.
Sheetrock fibatape or alkali resistant? Any dif?
Thanks….
alkali resistant. I thought you meant the fibatape made by customs, which is alkali-resistant.
Customs (Fibatape) makes both types, I have both. These days so many new products react adversely with each other, I wanted to be sure. Sorry to be a pain.
Once I used protectowrap on vinyl flashing – no prob, right? WRONG!!! No bitumin based products on polyvinyl chlroride or they melt, omg…..
I have an off tile question, but you have helped me before so I figured I would pick your brain. I have seen a website where the people are doing a faux concrete countertop with a product called Ardex featherlite- it looks like it came out O.K.- but I was just wondering if you have any experience with concrete countertops or have seen this method used before. Just trying to see if its worth a try or not and thought I would get a professional opinion before I embarked on a DIY “journey”. Thanks! P. Walsh
Hi Pat,
I have done concrete countertops but they are actually a very, very involved installation. Ardex featherlite is a good product too, although I’ve never done a countertop with it.
I am wanting to create a guest shower using concrete instead of tile. I have already followed your instructions on creating the preslope bed and waterproof membrane. What ratio of sand and portland cement would you recommend and will several coats of penetrative sealant be enough? I want concrete for theaestheitc appeal. I realize that it will require more upkeep (reapplying sealant) than tile.
Hi David,
You need to use straight concrete or hydrophobic (?) concrete in that application, and unfortunately I don’t know much at all about that type of installation. I do know that concrete or deck mud (definitely NOT deck mud) with sealer will not be sufficient for an application such as that.
Your post is GREAT!!! I am doing a bed for the bathroom floor, which is enlevel about 2 1/2 inches. Is wire required underneath to hold it together (on a 3/4 wood plank floor)?
Hi John,
If your mud bed will be thicker than 1 1/2 – 2 inches then yes, you should use wire lath to strengthen it.
Say, I’m working on making shower on an already cured concrete floor. I’m wondering what is the thinest amount of drypack mortar you should have above the waterproof membrane to keep it from breaking up?
Hey Brad,
3/4″ is minimum, 1 1/4″ is ideal.
Hi Mr Elf,
Thanks for sharing your experience with the world. It’s very generous of you and I wish more folks studied your site before embarking on a shower. I recently tore out a poorly installed membrane, and now that I can see the preslope ,well, it needs a fixin’ too. I know I can just scrape down the high spots, but is there anything I can do about the low spots ? If I mix up a small batch of mud can I just fill in, and then kind of ‘skim coat’ the whole rest of the deck, or do I need to chip it all out and start from scratch again ? I honestly don’t know if cement will properly adhere to itself.
Thanks, tip o’ the can to ya
Hi Natty,
You can as long as you put thinset over it first. Deck mud does not bond well to already cured deck mud, thinset will bond it.
Thank you kindly sir !! I’ll fix that up tonight, and resume my journey to having a bathroom back. Can’t thank you enough for all your help. If you have a paypal link (or similar) I’d like to drop something in the tip jar.
No worries Natty, thanks. Go out and get yourself a new rubber ducky.
How long do I have to wait before applying kerdi on top of the deck mud that I used to extend my kerdi pan?
Thank you
24 hours.
Hello! Do we need to apply a layer of thinset before the deck mud on the pre slope if we have a wood (not concrete) floor? We have the metal lath on top of the vapor barrier already in place. Thanks!
Hi Amanda,
Nope, just the lath.