dry pack mud vs. wet concrete

[Mike W.]

I'm sure this has been covered but, if you have the time to allow concrete to cure, why not use wet mud for a shower floor? I feel more confident shaping the bowl for pitch to the drain and getting the height just right at the perimeter of the shower and at the drain so as to accept the tile for a nice flush installation. Clearly, I'm not a tile contractor. I know they all use dry pack mud. But, I'm a carpenter and I *think* I can control the media better with wet. More time to work it and you can "cut it" down with a screed easily and then trowel it. If the only down side to wet is shrinkage BUT you have plenty of time for it to cure (I'll do other stuff for a few days) then why not? Thanks for any advice that comes my way.

[wilobe]

What type drain and water proofing are you intending to use?

[cx]

Welcome, Mike.

Shrinkage, cracking, too dense to allow moisture to pass through readily but porous enough to allow it to become saturated, much, much more difficult to shape into a flat slope, more difficult to create the accurate height at both drain and perimeter, are a few of the reasons that spring to my mind.

Even aside from the functionality of the two materials, I'd hafta bet against you every time and in favor of a good deck mud man as to the accuracy and flatness of your respective sloped floors.

But I've bet wrong before.

[Art of Stone]

I think you're taking a very safe bet there CX.

I am led to believe you have not had the fortunate opportunity, to learn the art of making exactly what you want from a good mud man, Mike. There is no comparison to being able to "sculpt" the planes you want versus pouring and troweling. Once you know how to properly work a dry mud bed planes, shapes and contours are done easily.

For wet areas a dry bed is a much safer way to ensure proper drainage of moisture.

If you focus much of your efforts and income towards tile, to fully understand the answers to your question, would serve you well.

I'd suggest learning more about the NTCA and what they have to offer and/or, finding a "Good" mud man to work with and learn from. What you would come to learn would likely open a new realm of the tile world to you.

Just my 2 cents.

[jadnashua]

In a conventional shower pan, concrete would be very problematic - it is too dense, even if you could shape it the way you want. Neither the tile nor the grout are waterproof, and moisture will get beneath it. Deck mud is porous, and will allow that moisture to flow down the slope to the weep holes of the drain...concrete won't. Once the concrete gets wet, it will stay that way unless you do not use the shower for a very long time, leading to wet grout lines, and the potential for them to now grow mold and mildew (mold takes three things, cut off any one and you stop it: moisture, food, and the spores - the only one easily controlled is moisture). If you were using a surface applied bonded membrane, you might get away with it, but deck mud would still be easier and cheaper.

Deck mud is sort of like playing with wet beach sand...you place it where you want it, compact it, and can still 'shave' a bit off for final shape refinement.

[lou432]

I must admit 30 plus years in the flooring trades and when I started to truly learn tile 20 plus years ago I was introduced to deck mud and the 100 plus showers i did prior to that was all wet concrete cause the guy that I was working with only knew wet concrete so thats what I knew . then i wanted to separate myself from him and others in my area doing it the same way so I started to educate myself and did a stint down at the CTEF and learned a bit of everything including deck mud.
What a difference and I must concur with all reply`s Deck Mud is so much easier and better for the application!!!
Deck Mud all the way!!

[Art of Stone]

I believe there is higher risk of efflorescence and/or grout lines that are not uniform in color when using a wet set, as well.

[Jim Cordes]

Its not about letting it set for a few days..unless by a "few" you mean 28 days?

All the above as for good reasons.. and trust me there are still more goods reasons not mentioned yet. Now is there even one good reason to not use deck mud?

Try it out, it really is not that hard, if you can do concrete you can do deck mud, its is inherently different but in a easy way..just like playing with sand at the beach.

[jwmezzanotte]

Im a Carpenter as well, but have lots of experience placing finishin concrete. Have done many pours into the thousands of sqft on my own (onviously with helpers) and have worked alongside other crews doing 5-10,000 sqft pours.

Im pretty comfortable with concrete.
Shaping deck mud is easier, no comparasin.

And if your concerned that it wont be strong enough (i was at first) try a sample, check it out the next day. You'll see, will be plenty hard.

Just make sure its mixed evenly (no sand clumps) and packed well. Give it a pass with a steel trowel when your done shaping. You'll never look back.

Also if your going to do a lot of pans, get a bucket mortar mixer. You'll love it, perfect for shower pans! Easy/clean/quick mixing.