How to Make Deck Mud

by Roger

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.

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Bill Hewitt

Roger,

I’ve just finished my top coat in a custom shower 34″ x 90″. Quite a slope to the linear drain which sits 18″ off the back wall (pre-determined by the builder). Your notes, comments and hints have been spot on- everything worked perfectly. Thanks, you have been a great resource!

Bill

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Chris

Hi Rodger,
I’m pouring a mud deck as you instruct,. I’m also using red guard to waterproof all the durarock walls, is it ok to waterproof the mud deck as well? I do have a vinyl liner under the mud deck.

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Chris SANFORD

Hi Rodger,
I’m pouring a mud deck as you instruct,. I’m also using red guard to waterproof all the durarock walls, is it ok to waterproof the mud deck as well?

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Bill

I’m putting in a drain and shower in a basement that has a cement floor- can I use the deck mud as the final floor as long as I have put a water barrier under it? And do I need to add a sealer to the top?

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Rodney

Is it a must to have the metal lathe on the shower floor. Or could I just put a plastic vapor barrier and put the deck mud straight on that??

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Robert D Ganote

This is a great site!

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mike

Hi Roger,

Your patience must be without end to answer all these questions, much appreciated.
I was wondering if you have a jig or something to cut the metal tile edge strips that helps make the corner look good. Seem difficult to get a nice corner with the metal.

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Roger

Hi mike,

I use a small miter saw with a metal blade on it.

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Luke

I am still confused on the deck mud, I thought I could use type n mortar for a shower pan. I see I previous comment where it looks like you advise to use deck mud over the mortar. I’m sorry to best a dead horse but I could use clarification.

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Roger

Hi Luke,

The previous comment was likely about going over an existing preslope made from type N. Any and all layers of your shower floor should be constructed using deck mud.

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Luke

Thank you!

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Tim

I’m considering deck mud to level a 100+ year old concrete basement floor. We have a new french drain type drainage system in place, but the old slab is not flat – up to two inches of variation. Since I want to finish about 800 sq ft, self-leveling compund would be $$$$$ and a new slab of concrete seems like overkill.

Do you think dry mortar with a vapor barrier underneath would work in this situation? It’s just going to be covered with vinyl plank. It shouldn’t get wet, it’s low traffic and it’s not going anywhere.

I almost feel like I could fill with gravel and put down a layer of OSB, but i want something more stable.

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Roger

Hi Tim,

If by ‘dry mortar’ you mean deck mud then yes, it should work perfectly.

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Monique

Hi there
I have just purchased a property with a full tiled bathroom with a walk-in tiled shower.
I have found a leak in the bedroom next door which is coming from the shower next door – where the wall meets the floor.
I have taken the gib/wall liner off in the bedroom and done a water test to find this.
There is a gap between where the wall tiles meet the floor tiles (the height of the floor tiles is higher than the height of the foundation concrete floor in the bedroom and the rest of the house because of the tiles being stuck on top). Silicon has been stuffed in here but it’s obviously not working.
There is no liner or any sign of a waterproofing membrane.
After removing the wet silicon to dry the area out + remove and replace the bottom floor plate for the wall, I am able to push 10 pieces of paper through from the bathroom in to the bedroom through the gap.
I am not able to do a full bathroom renovation at this stage and need a solution to:-
1) fill the cavity/drop-off/gap so that water can no longer sit in here and roll under the timber framing and into the bedroom next door.
2) best waterproofing solution for this dodgy installation?
3) can I fit a shower box over the top of the tiles and stop any future leaking?
Please note that I do not know anything about tiles and if products are recommended I will have to go to a tile shop and get.
I can’t get anyone to come in and fix it due to extremely tight weather proofing regulations here in New Zealand now. Everyone’s recommendations is to rip the bathroom out and start again except I am not in a position to spend that kind of money right now.
Your advice would be much appreciated;-)
Email: monique@plantcare.nz

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Monique

Can I:-
Staple some waterproof liner onto the back of the cement board that the tiles stick to from the bedroom side,
Then tuck this under the bottom of the tiles wall and flap it out over the edge of the tiles.
Then point a tile floor mortar into the cavity/gap from the bedroom (I would need to take the bottom wall frame off that I have just replaced which is fine as I have constructed this in 3 sections that I can currently move in and out for access purposes) and press the mortar up to the floor tiles so that the liner can be cut to curve and sit on top of the mortar and almost up to the level of the floor tile. The method to my madness is to create a barrier that encourages any water backninto the tiles and into the sloping drain.
Then waterproof membrane the tile mortar from the bedroom side and also through the gap in the bathroom by carefully lifting the liner.
Then use more waterproof tile floor mortar (what is epoxy grout and is it waterproof and could this be a substitute for the mortar?) as a grout on top of the liner and to seal up the front of the gap.
And last but not least, then put a liquid waterproofing liquid over the top (I am a landscape designer and we use a product over concrete to make it waterproof for fish ponds etc).
Last question: how do I protect the rest of the tiles if this all works? Do I just clean the grout and then spray a grout protector over the top of the grout lines? The shower looks fine, it’s just the dodgy workmanship underneath that you can’t see. Thank goodness the rot has all been replaced.

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Roger

NO. :D No matter how you waterproof that gap, it sounds as if nothing else below the tile floor is waterproofed. That means that the water you can see seeping out will simply find another place to leak out once you cut off that exit.

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Roger

Hi Monique,

The ONLY solution is to remove at least the floor and bottom row of wall tile and install a properly waterproofed base. Not sure what a ‘shower box’ is, I’m assuming an acrylic product which covers the walls? In any case replacing that floor with one that is properly waterproofed will be much cheaper than trying to do that.

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Jon Campbell

I did a preslope with Mortar mix at the recommendation of a big supply store employee now Im reading your stuff and am worried, should I proceed with my liner and just use the portland mix on the final mortar bed or maybe try a small layer of over the mortar mix bed? Any recommendations on proceeding?
Thanks!

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Roger

Hi Jon,

You should be fine with the preslope. Just use regular deck mud for the top deck.

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Roy

I poured and packed my shower pan 3 (using a 5:1 ratio) days ago, and it still has not cured? I know its cold in Michigan right now, so starting on the second day I began running a heater in the room. Today it is still not dry. Can you think of why?
Thanks,

roy

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Roger

Hi Roy,

Is it hard? I know that’s a weird question, but there’s a reason behind it. :D

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Loc

Hi I’m trying to pour the shower pan can I use 60 sakrete sand mix for topping and bedding plus 30 lbs of sand instead of the 60lbs quickrete plus 30 sand? Thank you very much for this website.

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Roger

Hi Loc,

Yes you can.

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Michael R

Will play sand work?

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Roger

Hi Michael,

Yes.

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Raffoul Ajami

HI Roger, I need to find a way to make my mud deck pre-slope (to be covered by a plumber liner) light in weight, its a a large shower that a builder hired us to do, and its on the 2nd floor with one (1) sheet of plywood over joists that are 24″ on center, (i know oh my God) and I cannot find any major setting material manufacturer that makes light weight shower mud, there’s dozens of light weight setting material on the market but not for mud deck, what ever you can help with it will be greatly appreciated and thank you for great articles.

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Roger

Hi Raffoul,

Oh my god! :D

Use perlite rather than sand.

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Nick

Hi Rodger can I or should I put a layer of waterproof membrane on top of my dried mud bed then tile and grout, or is it not needed. I will be using the kind you just roll onot with a paint roller

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Roger

Hi Nick,

If you don’t have a liner beneath your mud be then yes, you need to waterproof it. If you do, then no.

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Jose

Rojer, I’m a little confused about the ratio when mixing sand with Portland cement. When you say 5 to 1 ratio, do you mean for every 5 pounds of sand, one pound of Portland cement has to be mixed? Great website.

Thank you.

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Roger

Hi Jose,

That is correct.

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Jonathan R Hammon

Or any other unit of measuring, teaspoon, cups, Oz, quarts, shovels, lierall5any type of a container. It’s 5 parts, whatsoever they are, sand to 1 parts cement

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Kevin Link

You mention the mud should be sand and regular portland cement. I heard that “Sharp” sand was the best, do you have a preference for sand type?

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Roger

Hi Kevin,

Sharp sand is best, but difficult to come by in some areas. I most often use the regular quikrete sand sold right next to the sand and topping mix.

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James_morrell

Hi. I have a space from the deck/base to the bottom of the wall. Do I do the deck mud first and come back after it is dry and fill in the wall space with deck mud

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Roger

Hi James,

You can if you want to.

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John

I only have 1/4 inch between my hardiebacker shower floor and the top of the bottom flange. This means that my preslope will only be 3/4 of an inch at the wall and 1/4 at the flange. Will that work?

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Roger

Hi John,

Yes, that will work fine.

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Jay

Do recommend “Play Sand” or “Multi-Purpose Sand” for the 30lb mixture ratio to the 60lb Sand Mix?

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Roger

Hi Jay,

The multi-purpose.

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CountriSquire

Hi Roger,

Plenty of You-Tube and just finding your site and it looks like the best yet across the baord.

Admittedly, I haven’t read the plethora of info yet, but can you take a quick jump to Chapter 10?

I’m doing tub to floor shower conversion on concrete slab home. I’ve removed concrete and dug well below to make the P-trap location 180 degrees opposite and the finished new shower drain will now be about two feet inward.

I’m thinking the surface of the flange that will be below the ‘membrane’ should be located about 1-1/2″ above existing slab floor when I plumb it.

1) Does that sound correct for ~ 3/4 thickness on pre-slope and the same for the mortar bed above. Or should I allow 2″ to 2-1/4″ to allow for thinset and tile thickness as well? Tile not yet selected.

2) When the plumbing is done and the hole back filled should I fill the entire slab opening thickness with concrete or mortar? Now aprox. 14″x 28″ or so – this includes old area where tub drain came up ~ 2″ out from sill plate.

3) If using bricks instead of 2×4’s for curb, how does one secure the membrane on the top and outside surfaces of the bricks?

Let’s leave it at those three for starters, but maybe more as read the pdf’s.

With all the bucks involved, a re-do is definitely notan option.

With the sincerest of thanks!

Reply

Roger

When you say the ‘surface of the flange which will be below the membrane’ I assume you’re speaking of the lower flange? I also assume you’re using a regular pvc membrane and a double layer shower floor? If so…

1. You want the lower flange to the the depth of your preslope. So 3/4″ high. The membrane gets sandwiched between the upper and lower flanges, then the barrel threads into the upper flange – that is what lowers or heightens your drain for the finished surface.

2. It can be concrete or deck mud, either one works.

3. You wrap the membrane over the curb, then bend wire lath in the shape of the bricks and fit that down over the top of it. The lath holds the membrane in place.

Reply

Tuan Huynh

Hi great site by the way !
I try to build my shower and I going to use schluter foam

I have 2 questions
1st can I cut down a schluter foam ?because I like it’s lower
2nd how do I make it bonds to the concrete ?

Reply

Roger

Hi Tuan,

Yes, you can cut it down but it will be difficult to get it consistent. It is installed with thinset.

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Tom

Now that mine is installed, what is wrong with not having a pre-slope between the liner and top layer? Hopefully not much! Thanks for your time.

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Roger

Hi Tom,

There will be a layer of water that sits below the drain itself. It will NEVER drain, and it will be there permanently. A cesspool for all sorts of nasty things to grow.

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Kamran

Can you elaborate on the preslope? What does it meant and where will the water sit? In our implementation we have plywood, then cement board, then shower liner and then the mud pan that is sloped. Does this work?

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Roger

Hi Kamran,

I already elaborated on it here: Shower floor for tile If your shower liner is flat on the cement board, without a slope beneath it, then no, it doesn’t work. You need a preslope beneath it.

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