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.
Before placing a 1″ thick dry pack mud on my bathroom’s non-shower floor area, I need to install Nu-Heat’s electric heating cables to my 1/2″ plywood subfloor. Nu-Heat requires me to cover their cables with a 1/2″ layer of level-quik. So my question is – do I simply lay metal lath on the cured level-quik and proceed to pack on the mud? What about a de-coupling membrane such as roofing felt? What about nailing down the lathe thru the thin-set – or does it need to be anchored at all?
Hi Frank,
If you’re installing a mud bed you don’t need the slc. A decoupling membrane is (at least in the method in which you are referencing it) actually a cleavage membrane. It is in place under bonded mud beds to prevent the substrate from prematurely sucking moisture out of the mud bed thus weakening it. If it were mine I would install felt and fasten lath over it and install your mud bed and embed your heating wire in it. You can also do the felt and lath, install your cables, then the mud bed.
I can’t deviate from Nu-Heat’s instructions for fear of voiding the warranty. 50 square feet of wire cost me $555 and it follows a specific serpentine route wrapped around plastic anchors nailed to the plywood. So i guess i’ll do: latex primer, wire, level-quick 1/2″ thick, unfastened 15# felt paper, unfastened metal lath, 5:1 dry pack 1″ thick, thinset, tile.
Okay, then the proper way to bond the mud bed is not with felt paper and lath, once you get the slc down and cured use thinset over it as you set the mud bed. This will bond the deck to the slc. Be sure to keep a loudmouth or other continuity detector hooked up to your wires as you install.
sounds good to me Roger
I washed down my installed Hardiebacker 500 wall boards to remove all traces of dust. I was surprised how quickly it absorbed the water. Almost as fast as I applied it with a saturated sponge. Does this mean it will dehydrate my thinset and thus weaken it?
Hi Frank,
Yes it will if you don’t soak it down before installing thinset over it. Or you can skim coat it before your installation as well. Either will cut down the moisture absorption of the hardi.
What about using latex primer that you apply to substrates prior to pouring level-quick? I have some on hand.
That will work great. It gives it a really good bond without sucking the moisture out of the thinset. It works well.
My story of a drypack/mortar bed/screed/mud job/whatever you wish to call it failure this weekend:
I renovated my 11×6 upstairs bathroom in a framed house so I could relocate the tub to where the shower was. The idea being that it is impossible to have a clean shower stall. The glass walls and aluminum frames turn into a maintenance nightmare after a few years due to hard water mineral and soap scum buildup. And the kids are too lazy to spend 10 seconds misting the walls post-shower with that stuff that breaks down water tension. Therefore, a tub with a shower head and renewable curtains makes more sense. The orig tub was not able to receive a shower head since it was next to a window – besides, the Americast Princeton tub was too shallow for a normal soaking bath. This project required the rip-out of all walls and the tiled floor. The floor was 6×6 tiles set on a 1″ dry pack deck with 15# roofing felt and lath stapled to the 1/2″ plywood subfloor. The subfloor is 5/8″ out of level over a 6′ span. I never had a problem with the original tile / mud job. It was level, flat and rugged. Dropping a hammer from 4′ barely chipped the tile. It was even a pleasure to demo since it was not bonded to the subfloor. Therefore I was sold on the idea of replacing it in kind. In addition, that’s what all the union tile setters use at the big-city jobs I’m involved with. But then we heard somebody rave about their newly renovated bathroom’s floor being equipped with electric radiant heat. I had a pro tile guy stop by to give an estimate and he recommended the cable system vs. the mat system because the latter makes thinsetting the tile a hassle. (The mat gets thinsetted to the dry pack surface and the tile gets thinsetted to the mat). I also would not have to worry about damaging the mat if a tile cracked and had to be replaced – or if grout needs to be cut-out and replaced. So I ordered the cable and t-stat, but when I twice tried to schedule the contractor, I got no return call. So now I was forced to do the dry pack and tile myself. I did it as follows:
1. Secured any loose nails and added screws as needed to the plywood sub floor
2. Vacuumed, then washed all loose dust from same with sponge and bucket of water and let dry overnight
3. Applied one coat of Level Quik primer (~$10) diluted 50% and let dry overnight
4. Installed heat cable – making sure to test resistance before and after
5. Mixed a bag of Level Quik RS ($35) with a $12 paddle mixer in a clean spackle bucket and poured same. Repeated 2 more times to get the entire 43 square feet of floor covered to a thickness of about 3/8″ which embedded the cable and its plastic anchor strips. Note – I did not realize Level Quick would be so soupy as to drain thru the < 1/8" plywood joints. Next time I will caulk them before pouring. And no matter how nice the cured Level Quik looks from your standing position, try grazing it with a flashlight in a darkened room. I'm not an expert, but I believe the only way to truly achieve a flat and level plane with this stuff is to mix all bags at once in a cement mixer and pour it as quickly as possible in order to literally flood the entire floor in one fell swoop. My goal was only to encapsulate the cable – and cable mfg says Level Quik is the preferred method. Their other method is to trowel on a bed of thinset – but I guess the trowel could end up disturbing, or worse, nicking a cable. Another observation about Level Quik is that it developed hairline cracks after it cured. I'm not sure if they existed before I test- energized the cable 2 days after I placed the Level Quik. However, Level Quik does require lath to be used when plywood subfloors are involved. Obviously, I did not want to jeopardize the cable with metal lath. But again, the Level Quik was not used here for structural purposes.
6. Applied a coat of undiluted Level Quik primer (this quart goes a long way) onto the Level Quik and let dry overnight. I did this in lieu of using felt paper. The tile forums claim the sole purpose of the felt paper is to prevent the substrate from wicking moisture from the hydrating dry pack. The primer acts as a wicking barrier. It actually gave the Level Quik a sheen after it dried. So, I had a choice – buy a $20 roll of felt and have its high excess sit in my shed for years without any further use, or use the primer which I already had in hand.
7. Cut 27" x 97" metal lath sheets (@$9) to size with an angle grinder and overlapped them 2". To prevent curl-up, I tucked the margins under the sheetrock wall boards which came within 3/8" from the Level Quik surface. I took this extra step for fear of the lath curling up as I walked on it. In hindsight, it was a waste of time because the sheets remained flat despite not being secured down. Lath was not secured because it did not want to risk piercing the expensive concealed cable system with the roofing nails. And I also want the drypack / tile slab to float on the substrate to mitigate cracking due to different expansion rates from the substrate. Although in reality, it seems to me that a 43 square foot floor is less prone to stress than say, a 100 sq. foot floor(I kept reading about de-coupling and cleavage membranes)
8. Using a pointed shovel, I blended a 60# bag of Sakrete and/or Quickrete sand and topping mix in a wheelbarrow with a half bag of 50# of play sand. I gradually added 11 cups of cold water to get the ratio that allowed me to make a "snowball" from which no water could be squeezed. In later batches I switched from Quickcrete to Sakrete play sand. The latter was very damp and I needed much less water. It was also easier to divide the 50# bag in half by slicing it down the middle, folding the 2 halves together and continuing to sever the bag. The dry sand spilled uncontrollable when I sliced the bag at midpoint.
9. I used my toilet flange as the base point for the elevation of the dry pack bed. I used spacer rings from a plumbing supply house to build up the adjustable flange to a height of 1" above the Level Quik. I packed mounds of dry pack in the room corners with a float. Using a straight 2×4 and 4' level with one end on the flange and the other on the mound, I tapped it down the 2×4 until level. I then packed down a ridge of dry pack with a 2×4 spanning the mounds. I then dumped and tamped dry pack between these 'screed rails" and used a 2×4 to screed it level. I went back over the screeded surface with a steel float – but got better results using a pat-down action rather than my amateur trowelling [floating] action. I don’t understand why I leave marks and ridges when floating with either my steel or aluminum trowel – after all, I consider my drywall taping damn near professional. When I got done placing and screeding the first of two main floor portions of my slightly L-shaped floor, I placed a straightedge across the dry pack surface 90 degrees opposite to the direction I had been working to do a cross-check of the surface. Unfortunately it was not nearly perfect. I had to spend half an hour re-screeding in different directions to get a better result. I know it's bad to disturb placed masonry because it weakens it – but I had no choice. In the future, I will not rely on simple dry pack screed rails. Instead I will improve them with temporary 1/2" thinwall conduit pressed flush into place. It has got to be more accurate for a novice to glide a 2×4 screed board across metal. And the screed board being a 2×4 is too heavy – you're probably better off with 5/4 poplar if you can't afford a set of aluminum or magnesium ones. When the dry pack installation was complete I skimmed the slab with a flashlight. It's amazing how many issues that reveals. I had to go back and smooth out the ridges and craters with a trowel by laying on a plank suspended from wall to wall. I read somewhere that there is a 30 to 45 minute open time (workability time) with 5:1 dry pack. My experience on that day proved it's easily double that. Weather was cool and damp outside – if that's a factor?
10. Placed a sheet of poly, weighed down with boards at the perimeter, over the dry-pack to damp cure overnight.
11. 36 hours later I removed the poly and used a plastic bristled brush to remove the loose particles from the surface and found it alarmingly easy able to brush my way deep into the material. There was scarcely a hard surface anywhere! So I spent the rest of the morning removing the bad mud. The stuff crumbled easily and came up in large chunks despite being pressed into the lath. Material went thud instead of clink when struck with a steel tool. All that time wasted. Not very happy. So what went wrong Roger?
12. Something to take note of: When I asked for a 3:1 cement / sand verification on their sand & topping mix, Sakrete told me, "When doing a dry pack for tile applications we recommend the Sand Mix to be used as is, not to mix any additional sand with it. One of the most common applications with the Sakrete Sand Mix is for dry pack applications. Let me know if you need any additional information."
The workability time has more to do with the hydration rather than the actual ability to work with the mud. I believe that may have been part of your problem, as well as damp curing it. Do not damp cure mud beds. I have not, do not, nor does anyone I know, cover mud beds with poly. I don’t know whether that contributed to it or not. I do know working your mud for over an hour absolutely did.
If you want lath in your mud bed in that application it needs to be in the middle of the bed, otherwise it does absolutely nothing at all – nothing. When used over the substrate, under the mud, it is to bond the mud bed. If you want a bonded mud bed you need to use thinset over slc, as I stated above. I also do not know if that had any negative effects, I wouldn’t think so.
Hi Roger,
Just curious, what is the purpose to create the sand/cement ratio of 5:1? Why can we not just use sand/topping mix right from the bag at the 3:1 ratio? Is it for better for crack prevention, water drainage, ?
Final deck created last night. Making the curb today.
I purchased the ebooks, Traditional Shower Waterproofing and Tile Tips. Both very good with lots of great info! Thanks!
Hey Ed,
For both drainage and crack prevention. More sand means water can get through it more quickly and it can compensate for more movement in the substrate being dissipated through the thickness of the deck without transferring it through to the top layer where the tile is.
HI Roger
I like your forum and the advice I have read.I am in the process of demoing my bath for the second time in 15 years I plan to remove the Cast Iron tub and replace with just a shower which brings me to these three questions.
? When I begin to tile is their a way to avoid cutting the tile where the back wall meets the floor at the opposite end of the drain since this is at an angle due to the 1/4″ requirement ? is it better to tile the floor first than the walls or walls than floor .
? Can backerboard be used on the shower floor in place of of the deck mud and than use thinsit to set the tile.
Thanks
Hi David,
I don’t quite understand what you mean by ‘is there a way to avoid cutting the tile’ in that area? I prefer installing the floor tile first. No, you can not use backer in place of deck mud.
Roger,
Thanks for everything, but again newbie question, please define “beat the hell out of it” What tools would you use. Just with trowl?
Hey Adam,
You just want to ensure that it is packed tightly and there are no voids in it. You don’t need to stomp up and down on it, but if I phrase it as ‘beat the hell out of it’ people usually get it packed well enough.
I use a magnesium concrete float from Home Depot. With either that or a wooden float you’ll get the best finished surface on it.
Thanks for all the useful information you provide. I realized that I under calculated my drypack materials, and finished coverage of the area I was working on, and it has now setup. My question is this, can I now mix new batch and lay on top of what I have already put down so that I can propery scree and level area? Thanks in advance.
Hey Willie,
If you put down a layer of thinset first. You need to tie the new into the existing, deck mud over cured deck mud doesn’t do that well. Thinset will.
Does it matter if it’s modified or unmodified? Thanks again!!
Nope.
Hey Roger
Okay, I may be over thinking this, as I have the tendency to doing so, but the 5:1 ratio of sand to cement, is that weight or volume? If I take 3 five gallon buckets of sand and add 1 five gallon bucket of cement (and a little water of couse), would that be the proper mix for the deck mud??
Also, I have a 3’x4′ shower, so how much sand/cement will I need to do only the pre-slope if I use your suggested thickness of mud?
Sometime I just feel like such a rookie. Oh yeah, that’s right, I am one!
Hey Donald,
Both. Either. Whichever you want. The 5 : 1 is not anywhere close to an exact ratio. It varies from 4:1 to 6:1. Most guys just work it until they find the mix they like. I prefer the 4.8:1 ratio, I measure it by weight. A lot of guys do it by shovels-full – really.
Stop overthinking it and build your shower!
Not an exact science (4.8:1)?
Thanks again for your advice and good humor!
Roger,
Laticrete has a video for their floor drain. They install the backer board first and then the mud deck up against it. I verified with them “LATICRETE Bonding.:Flange Drain, which can have the backer board installed first.” Do you have experience with this? Will this tie the walls to the floor and cause trouble?
Hey Jerry,
Yes, I have experience with that. It will cause no problems at all installing the backer first. It’s easier to tie in the floor and wall that way.
I have a quick one. I am remodeling an existing scratch built shower and i am wondering if I can run my deck mud right over my old tile floor? The base was built using deck mud, rubber membrane, more deck mud, then thinset and slate tiles. The slate is not going to come up easy, and I don’t want to redo the shower base. I was thinking about laying another layer of deck mud over the tiles. I have enough room for the drain to be raised up about 3/4″, so my layer of deck mud would be about 3/4-1″ thick. Will this work? Any other suggestions? Maybe just a skin coat of thinset? The slate was sealed at one time, but that was years ago. I can use a grinder or multi tool to score the surface of the slate if that will help adhesion.
Thanks!!
Hey Jeff,
As long as you have room for the drain you can sand or otherwise scarify the surface of the slate, install a layer of thinset to bond the deck mud, then install a new layer of deck mud on top. No problem with that.
Thanks for the reply Roger. This site has been Extremely helpful! I do have another question about your response. Would it be possible to tile directly over the layer of thinset that I put down over the old shower floor? The slope is still there, and the floor is certainly waterproof (rubber membrane sandwiched between previous pre-slope and mud deck). The reason for my hesitation on the additional layer of deck mud is that I don’t have a ton of room left in the drain, so the thickest I could lay the new deck mud would be about 1/2″. That seems pretty thin for that type of deck mud. Maybe I can eek out 3/4″, but that’s pushing my drain height. I could however build the deck mud a little thicker at the edges of my shower, and taper down to 1/2″ at the drain. This will probably increase my slope, but is there much harm in that? Basically my question is 1)Do I need to install more deck mud and 2)how thin is too thin for said deck mud.
Thanks!
PS. I love my dog!
You can go 1/2″ with deck mud if needed. You can not go over about 1/4″ with thinset without compromising it. You can do either, depends on the amount of room you have.
Hi, just found your website and have learned a lot already!
I did a small shower successfully, in the past, using premixed deck mud. Now I’m hoping to tackle something bigger. I have a large utility room I want to tile and slope to a floor drain in the middle. Approx 11′ x 9′. Can you tell me how to handle this in terms of set-up time and multiple batches of deck mud. I plan on using your sand topping mix and sand formula. Thanks!
Hey Wayne,
Same way as a great big shower. It’s really that simple. The best thing to do is make sure you have all of your lines marked out (height at the perimeter, etc.). If you have the tools and ability cut yourself some 1/4″ strips of plywood and set them on your floor at about two or three foot intervals with the proper slope to them – 1/4″ per foot. Find your perimeter height by measuring the farthest corner of the room from the drain and multiply 1/4″ per foot. Mark that line all the way around the room then, beginning at the drain, shim those strip up at the walls so the top of them are at that line. Do that all the way around the drain then fill it all in with deck mud, pound it down and screed the mud off using the strips as a guide. As you get the slope in each area finished, run a blade along each side of the strips and remove them, then fill in the gap. This will give you a perfectly sloped floor all the way from the perimeter to the drain.
Thanks Roger!
I really like the, 1/4″ strips of wood to help me keep the slope right, method.
Do I need to worry about multiple batches setting up at different times and it all adhering well enough together?
Not really. Just be sure to chop a new batch into the old as you work through different batches. In other words, don’t just end one batch at a straight line then begin another without chopping them together to mix the batches into one another. You can always spray the last batch with water before chopping in the new stuff, too, that will help it lock together.
Hi Rodger-great forum and advice. I’m in the process of building a mud bed for my 3′ x 4′ shower. I’m using a linear drain and wondering what you would suggest concerning plumbing the drain. The drain is 3′ long so I won’t be able to turn it once set in the drain pipe (on a threaded jacking collar) to adjust the height. Would it fly to set it in the dry pack mortar with the drain pipe going into a ridged PVC pipe w/out glue or a hose clamp (so I can adjust the height?
Also will I need to add material on top of the dry pack mortar or can I put thin set and tile directly on the mortar after it has cured for 24 hours?
Thanks for the advice-yes I’ll buy your book too!
John
Hi John,
You attach the drain to the pipe, all glued and set, then create your mud deck to the height of the drain – not the other way around. You need waterproofing of some sort over your mud deck. This can be a liquid membrane like hydroban or redgard, or kerdi or similar sheet membrane. But you do need a waterproofing layer over it.
Hi Rodger
Thanks for the quick response. I’m using Redgard as a membrane over Hardi-backer board on the walls so it makes sense to use the same stuff on top of the dry pack mortar mix. My concern is getting my drain at the proper level so my tile (I’m using 1/2″ thick travertine) and the drain grate are level. So I’m scratching my head about how to get any water that gets thru the tile and grout to go into the drain-since the top of the dry pack mortar mix with the Redgard membrane will be 1/2″ + the thin set below the top of the drain.
Thanks in advance for suggesting a fix.
BTW my linear drain does not have weep holes. I’m installing the shower floor on a basement slab floor. I do have access to the pee trap and sub slab drain pipe due to a hole in the slab left by the last guy. Guess I could use a liner between the slab and dry pack mortar mix and let the water “weep” into the existing hole once I fill it with pea gravel? What do you think?
Linear drains do not have weep holes. They are topical drains. Do not allow the water to weep into the existing hole! The only liner in your shower floor should be the topical liner which goes over the deck and the top of the drain flange to completely waterproof your floor. The grate in the drain adjusts to the height of your tile. If you are not using a topical membrane on your shower floor then you can not use a linear drain.
Hey John,
You haven’t mentioned which linear drain you’re using. The three main brands (around here, anyway) are Schluter, Laticrete and Pro-Line. All of which have adjustable grate supports to raise or lower it to the height needed to be flush with the face of your tile floor. The drain is in two parts – the lower flange which is set flush with the top of the mudded floor, then the membrane placed over it, then the grate which simply covers the hole in the tile installation which will be flush with the tile. Do you have your drain yet?
Hi Rodger-Hope you had a good holiday.
I bought a Linear drain that I found on Amazon.com from the Vincent Buda Company. Frankly I could not bring myself to pay over $500 for a &^*%
drain! I paid around $270 and found a “drain kit” at Home Depot that will allow me to install the drain with a membrane that feeds the “weep holes” on the drain. These are all new concepts to me but I’m learning. Thanks for the help!
Your dry pak mix, will it bond well to poured concrete floor , in a commercial application.
for very large areas , 11′ X 30′ any suggestions on how to prevent swails or lower & higher points
Your response is much appreciated
Hey Clayton,
Dry pack, or deck mud, does not stick to anything. If you want it bonded to the concrete you need to install a layer of thinset beneath it. If screeded properly then it should be absolutely flat, it’s a skill, there are no secrets to it.
Just take your time with it and you should have a flat substrate when you’re finished.
To pour a 5 x 3 foot pitched base, I think I’ll need two 60 lb bags of Quikcrete topping/sand mix and 60 lbs of sand. Can you confirm that? Also, can I mix that in thirds so as not to overload the wheelbarrow (or me!), or should I combine all of the ingredients in one big mix to ensure they’re mixed consistently? Thanks so much for doing what you do!
Hey Mike,
Yup, two 60 lb. bags of S&T mix and one 50 lb. bag of sand. Yes, you can mix it in as small of batches as you need.
Thanks, Roger. I really appreciate the attention you give to all of us tile-expert-wannabes! The overall slope is toward the drain, but there’s a broad “lip” that would take a lot of sanding or scraping to let the few tablespoons of water flow to the drain that it is holding back. So, if I understand you, I’m fine? I have more questions about what size trowel notches to use for thinset under backerboard, but maybe I should post that in your flooring section!
Yup, you’re fine. You can post all your questions here. They all show up in the same place in the back room regardless of what post they are asked on. I actually prefer you ask it here, that way I can keep track of what you’ve asked and what I’ve answered for your particular project. I normally use 1/4″ x 1/4″ square-notched trowel under backer. That may be larger if your floor is wonky.
(Yes, wonky is a word. My daughter told me so…)
Roger, Thanks so much for that reassurance on the shower pan.
I’m haunted by your remark to “never” use pressure treated wood for the curb. I was planning to leave the pressure treated curb in place. It was there for over ten years. Can I figure it is done flexing?
Now for the toilet flange. Should I take it up so that the backerboard and tile can go under it? (Thus covering more plywood and protecting it from possible leaks?) Or leave it where it is and work around it? (Thus raising the toilet, and leaving less of the bolts sticking up through the base of the toilet, not to mention having more gap for the wax ring to fill between the toilet and flange.)
Another thing: after I put the liner in, shim the studs and add a vapor barrier, my preference is to put the backerboard almost to the pre-slope so the upper layer of deck mud holds it to the wall, as you say. Does that create an issue with wicking?
And another one I lose sleep over…”How flush is ‘flush’?” When I screw those nifty screws with the ribbed heads into backerboard, they nearly always remain a little above the surface by 1/16th of an inch or so. What I call “flush” when working with drywall means you could swipe a putty knife over the spot without it contacting the screw head at all. The only way I can sink the special screws into the backboard like that is to back the screw out again, lift the backerboard in the air, and spin the screw in the backerboard until the head is flush, and then lay it down and attach it to the floor. The Hardiebacker website, I think it was, said if you can’t get the screws flush, use roofing nails–but they stick up, too!
Another problem I have with the 1-1/4 inch screws is that when I screw the backerboard to furring strips, the screw hits the concrete or concrete block just before the head is flush, and acts like a jack to lift the furring strip off the wall. Not good. My big box store doesn’t have a 1-inch screw. What do you suggest?
I would suggest two things: A stronger drill and larger (thicker) furring strips. You didn’t say what type of backer you’re using but there are two different types of those screws. One for the hardibacker type boards (layered) and one for durock type boards (chunky). Hardi screws work with durock, not the other way around. You can also order shorter screws online.
Nope. Any backerboard will wick to some extent, but it will not cause a problem. The weight of the water in the backer above it (that gets behind your tile) flushes it down and through your shower with every use.
You can figure it’s done flexing. Whether or not is actually is…well, that’s a crap-shoot.
You can either take it up above the backer or use a thicker wax ring, either one works fine.
You convinced me, Roger. I took out the old curb and put in a new one. Wonder of wonders! The old one had a bit of wobble and “give” to it. The new one is solid! Thanks for the hint!
As for the screws, it turns out I had the Durock screws instead of the Hardiebacker ones. I haven’t tried them yet, but my hopes are high again! Thanks!!!
My wife and I had our hearts set on using 20 inch tiles in the shower floor and walls, to match the ones on the master bath floor (and have less grout to keep clean). Having put in the pre-slope, I’m realizing the geometry doesn’t work out to have things line up the way they can with small tiles. It seems you either sacrifice the level edge at the wall, or else have the tiles at different levels and angles where they meet. But a tile store told us we could use the 20 inch tiles. How bad will it look on a 3×6 shower floor with the drain in the middle but off-center? Can you direct me to any pictures of something like that?
I don’t have any pictures like that. You can not use large format tiles on a shower floor with a center drain. It must be a flat plane sloped to one side or the other (linear drain). The perimeter of the shower should still be level all the way around, no need to sacrifice a level edge. It’s apparent that if they did not tell you that you’ll need a linear drain to utilize large format tile on your shower floor that they have no idea what the hell they’re talking about.
Or…I’ve misunderstood your question and I have no idea what the hell I’m talking about.
What I was thinking of was having four planes meet at the center drain, each with a 1/4-inch-per-foot slope. In a 3×6 shower, the slopes to the side would be 1.5 feet each, but the slopes to the ends would be 3 feet each, making the ends 3/4 inch higher than the middle of the sides. for the last foot and a half towards the end of each side, the sides would slope up to meet the ends. It would mean the tiles on the shower walls would have to be trimmed to fit, but how bad could it look if it was all symetrical? Since the four planes all have the required slope, it should be within code, shouldn’t it?
(Oh, and I tried the correct screws. Way better, but unfortunately, still not truly flush. Very slightly raised above the surface.)
Oh.
Yes, it will work. HOWEVER! it is a tremendous pain in the ass to get the geometry correct. I do not have a photo of the ones I’ve done (I’ve only done two of those). But yeah, it works.
Your reply to Mike makes me think the way to tackle this “little challenge” (in addition to careful planning and making of screeds for each plane) is to mix a small batch of mud, do one plane, then mix then next and do another until it’s done. Would you do it differently if you were going for a third one to please the love of your life? (Of course, if I screw it up, and take a few more weeks to get it right, mine might not be so pleased!)
To be honest I would likely cut the tiles before I created the mudbed, form the mudbed as closely as I could by eye leaving it a bit over-filled, then use the cut pieces and work them down so you have a flat plane beneath the tile, then remove the tile and let the mud cure.
Toldja, pain in the ass.
hi Roger i am having a problem i have layed my mud deck with self leveler and it has now dried (24 hours) my slope is not slopped enough can i just add then set to the corners or what can i do to have more of a pre slope thank you for helping all of us DIYers who would love to know what there doing is right lol!
also i can see cracks in it slightly not bad
Hi Anderia,
Why on earth would you lay a mud deck with self-leveler??? As I described above the sand and cement mixture is the proper product, self-leveler does not belong there. It is not sloped because it’s now leveled, the self-leveler did that all by itself. It’s right there in the name.
Ready for the bad news? That needs to be removed and replaced with ONLY the sand and cement mixture I described above. Read through this before continuing (all five of them):
im stumped is there any other way i dont see how im going to beable to get it out its pretty solid i cant just put thin set in the corners for my slope
i have read your site for days but was stupid enough to relay on the guys at the home improvment center to guide me wrong and it was in the tiling dept. too and as you probly know it was on the high side cement and sand would have been easier on the pocket. i do plan on using the red gard system so glad your here for us diyers i do thank you
You can but I honestly don’t know if it will hold up long-term. Sand is in the deck mud mix so it can shift around to compensate for regular structural movement. Cured SLC will not do that. The fact that you see cracks in it already (from shrinking as it cured) is indicative of a bed which is too dense to compensate for movement. That movement is going to end up moving your tile, which may crack your tile or grout.
one more question can i use redgard on floor before liner or will it cause mold
and also can i just put the deck mud mix over what i already have my curb is 6 inches high made with cement blocks over built there maybe for good reason ok beer needed and prob no sleep tonight thank you so very much
lol sorry about being a misfit ive learned my lesson
you rock!!!
You can put wet mud there. It’s deck mud with one additional part of powdered mason’s lime. It makes it sticky.
Redgard won’t do any good on the floor. You have no way to tie it into the drain. And yes, it may cause mold.
i finished the deck mud today it looks really good as good as mud can look
will start on liner and top deck mud tomarrow thanks for all you do we really do need you lol thanks again roger 
Hi Roger,
I’ve been doing a lot of reading on your site and have learned a lot. I’m getting ready to make deck mud and I was able to get a bag of portland cement, but I’m having a problem finding sharp sand in my small town. The hardware stores do not have sand/topping mix they only have play sand and silica sand in different grits. I can get plaster sand or concrete sand in bulk at a local supply company. What sand would be best to make deck mud with?
Thanks,
Jason
Hey Jason,
Fine silica sand works very well. After that the plaster sand works well also. Either is fine.
Roger,
Why do we want to use fine silica sand? I thought the sand had to be course to allow water to penetrate it. Given you are the expert what size do you recommend?
Thanks,
Jason
I prefer the way it works with the mud. Makes it easier to pack and form. Any sand you put in there will allow water to penetrate it easily. Provided you get the proper ratios the size of sand is not extremely relevant.
The Sakrete sand mix says its is for slabs 1/2 inch to 2 inches thick. (I’m mixing in 30 lbs sand per 60 lb bag to make deck mud.) There’s a slight slope to my plywood floor which means I’m 1-1/2 inches at one end and 2-1/4 at the other too get a level pre-slope bowl. Is that too deep for the deck mud? Or should I screw down a half inch of concrete board under the metal lath at the deep end to keep it under 2 inches?
Hey Kenneth,
You can have a six-inch deep mud bed if want. 2 1/4 inches will not be a problem at all.
Thanks. Now that the preslope is in, I found I was short a bit of mud, so there are a couple of shallow ponds about 1/4 to 3/8 out of the line from corner to drain. Is that close enough for the pre-slope? Or should I mix some more deck mud and fill in? If it needs a thinset slurry to bond, can you give the recipe or direct me to it?
Hi Kenneth,
As long as it slopes towards the drain and no part of it slopes towards the wall you’re fine.
Hello Roger,
I wanted to know how long a deck mud must dry or cure before applying redguard. Thanks so much.
Hi Dominick,
48 – 72 hours is what redgard requires.
Roger
Hey I hade a couple of questions. Im gonna lay 1500 sq feet of tile out side and I want to level the floor with dry pack. What do I use to bond the dry pack to the concrete and should I apply red guard over the dry pack leveled floor?
Hey Mike,
Regular thinset can give you a bonded mud deck. Just spread as much as you’re working over at a time. Unless you want the floor waterproofed there’s really no need for the redgard, a mud deck has plenty of compensation capability for regular movement (provided it is at least the minimum thickness) so you don’t need crack isolation.
Hi Roger!
Got your book and am working on a small 36×36 shower pan. I couldn’t find the premix product that you mentioned and ended up with this stuff called Rapid Set Concrete All. The problem is they don’t tell you what the concrete:sand ratio is so I have no clue how much sand to add to get near-or-around the 5:1 ratio. Any suggestions?
James
Sorry… It’s “Cement All”… Not concrete all.
Hi James,
You don’t want to use that. It is a cement ‘grout’ repair product. Your best bet is just to get regular portland cement and mix it with sand at a ratio of 5:1.
Hi Rogers,
thank you for that useful and good information.
Can I use the same mud system to float a floor for tiling? Does the mixture have to be different?
Hey Richard,
Nope, same mixture for a mud floor.
Hi Roger, I have been reading your site for weeks now. Thank you for all of the good information. We did our first mortar bed over the weekend. But I noticed in one section it is crumbling on top and the shop vac can pull out quite a bit and it leaves divits about a half to one inch deep in places. We mixed the ratio as you said and beat the heck out of it. Even smashed my finger with the sledge hammer for proof of that. Do we have to start over or can we thinset it and move on to installing the Kerdi wrap? Thank you in advance. Marie
Hi Marie,
You can thinset it and go ahead with your kerdi with no problem.
Roger,
I’m sure you hear this a lot, but you have a great website and it is an excellent source of information for DIYer’s like myself. With that said, Thank you.
I’ve just had a first time no-go with my pre-slope deck mud mix and the entire bed was sucked out with my shop vac. With that being said, I took a 50lbs bag of quikrete sand and mixed 10lbs of portland cement into it, mixed it with a little less than a half gallon of water (37″x44″ shower pan) and packet it in. The shop vac was able to pull everything out the next day. So, now I’m ready to execute the 2nd attempt….. I bought a quart of Quikrete Concerete Acrylic Fortifier from HD and planned on using a few ounces of that in my mix, I also think more water and concrete would improve the bond and adhesion. Have you ever used any of these aditives? Your input would be greatly appreciated.
Hi Mark,
Your mix is correct – it sounds like it wasn’t packed hard enough. You really have to beat the hell out of it. I have used the additive and the only difference I’ve really noticed is that it makes my deck mud more difficult to work with. I haven’t noticed any difference in a regular residential shower. It won’t hurt anything to use it, though, it will help your deck mud hold together better. You need more than a few ounces, though. If you use it mix your mud about 1/2 and 1/2 with the admix and water or with just admix instead of water. A few ounces won’t do much for you.
And beat the hell out of it.
Thanks Roger,
Now can I buy that in a store or do I have to buy it online? I am in Canada and havnt seen any noble products anywhere.
You’ll need to get that online. Even the places around here that have noble don’t have that. You can get it from Contractor’s Direct, but you may be able to find it elsewhere cheaper. I really don’t know what the normal pricing is, I don’t use them. Contractor’s direct is usually right in line with most of their stuff.
Awesome write up! I am about to make my shower bed and would like to use a ”normal pvc drain” with kerdi membraine over my deck mud. is this possable? I read about the divot but dont know how to do it. Can I just bond the kerdi to the bottom flange and clamp it with the top like you would with rubber membraine, then thinset tiles to top flange ignoreing the weep holes?
Hey Aaron,
You can, but you’ll need to use NobleFlex Drain Flashing. (It’s at the very bottom of the page) It is essentially bonding the flashing to the bottom flange and clamping it down – you can’t do it with just the kerdi, though, it’ll fold up all weird and you can’t get it flat. I know – I’ve tried.
You’ll still be utilizing the weep holes, they will be above the flashing. The divot is just filled with mud then the tile installed directly to it.
Roger,
Thanks for your blog. I had a framer that said he could do the dry pack bed for my basement remodel. He laid a membrane first on the wood floor than the dry pack with mortar. I can suck up most of the pan with a vacuum it is so dry. I believe after reading your answers above the i need to take out the dry pack and start over. But the other question i have is that the membrane was installed below the dry pack. I was plan on laying thin set and tiles over the dry pack. is this correct?
Thanks
Yes, it should be removed. That is waaaaaay too dry. More importantly, however, is the lack of pre-slope beneath the liner. Yes, the tile is bonded directly to the mud deck. You can read about the proper way to build a shower floor here: How to build a shower floor for tile