Dry pack mortar question: shower pain

[Jake20]

Greetings,

I appreciate the posts and advice I've perused since discovering the site some time ago -- excellent, high - yield info.

I'm a new DIYer; bought a house that turned into a money pit, thus, I'm attempting many of the renovations myself. My focus is on the master bathroom; specifically, the shower pain ("pan,"a Freudian slip).

I forwent the out of the box shower pans given the cost, placement of the shower drain, and the high likelihood I'd mangle it from the getgo. A mortar bed seemed to be the way to go...or so I thought.

I scrapped my latest (third attempt) pan this morning. The first 2 tries were unmitigated disasters and not worth mentioning, third seemed promising. I'm using Quikrete Sand Topping mix admixed with the acrylic fortifier the company recommends. After what I believe the appropriate consistency was achieved I went to work: formed the screeds and then filled in the rest of the floor for the preslope. I then left it alone for 2 days.

I came back to the moon: craters, cracks, and very brittle mortar. The perimeter was intact and solid but the rest was garbage.

I feel like I'm not packing the mortar as tightly as I should, in the center of the pan, resulting in the failure. I formed the perimeter via hammering a 2x4 to pack the mud. The packing was not as robust for the rest of the pan. Am I on the right track in implicating my technique for the lousy pan? Thank you.

Jake

[jadnashua]

First, don't use the acrylic admix! That can make it sticky and harder to screed to the desired shape plus, at least on the top layer, it NEEDS to be porous so it can drain. The admix will tend to make it less pervious and create problems.

You may be mixing it too wet as well, and many prefer the mix to be a bit leaner. I think that one out of the bag is 4:1, but a 5:1 mix is easier to work with (that's sand:cement ratio). It needs to be wet enough so if you grab a handful and squeeze it like making a snowball, it sticks together. It shouldn't drip.

Working with it is sort of like wet beach sand, not putty, or concrete.

[Tiger Mountain Tile Inc]

Don't use the admix. If you're doing a mud pan then you want water to absorb and run through your pan down to the waterproof liner.

If you're using Quickcrete sand/topping mix from a hardware store then the mixture on it is 3:1. Ideally, you want to be 4 or 5 to 1 which means adding some sand to the mixture.

I forget which kind is best. Seems to me it's the play sand? Maybe CX or Davy can correct that if it's wrong.

I'm thinking you may not be adding enough water if you are getting craters. What would happen if you vacuumed the surface?

Do you have pictures of what you have right now?

Additionally, you if you can upload some photos of how your liner is done, now would be the time to get some second opinions.

Did you do a flood test on it to make sure it's water tight?

[cx]

I think we've decided that the Play Sand is usually the best choice in the Quikrete products, Jim, but that stuff varies rather dramatically in different regions. A fella just hasta find what's best in her area.

My opinion; worth price charged.

[John Bridge]

Hi Jake,

We have a short article on making deck mud from sand topping mix: https://www.johnbridge.com/how-to/deck-mud/

[Davy]

When I mix dry pack from scratch, I try to find the Qwicrete all purpose sand. It has multiple sizes of grit from very fine to pebbles up to about 1/8. But like Cx said, that may vary in different regions.

I usually notch a lattice stick about the thickness of the tiles like in this picture. That way the mud is left a little lower than the drain. Then I go over the mud with a flat steel trowel to slick it down. This gives it a crust on top that helps avoid erosion. It's not concrete so protect the surface.

[Jake20]

Thank you for the replies. I used the acrylic fortifier on the pre slope so hoping it won’t make much of a difference. I’ll hold it with the 2nd mortar bed and will make the recommended changes to the mortar mix. I have yet to place the liner.

The latest iteration of the pre slope seems to have gone better, much more sound. Instead of building the central pan from the floor up I dumped a substantial amount of mortar, higher than the screeds, and really packed it tightly. I then used 2x4’s to carve the appropriate slope; should’ve looked through the prior threads more carefully as that seemed to have helped that person.

[cx]

Originally Posted by Jake

I then used 2x4’s to carve the appropriate slope

Jake, I think you'll find your life a whole lot better if you'll find something smaller/thinner than 2x4 lumber to use as your screed tool for shaping your mortar bed. Even a 1x with nice sharp edges. If you can gain access to some aluminum or magnesium screeds, you'll be even happier. Five-gallon bucket paint stir sticks work well for the final touch-up or/and shorter runs.

Your mortar wants to be firmly packed, but you do not need/want to beat it into submission. The perimeter screeds want to be packed maybe a bit more than the field, but you still don't need to overwork those. Very firm on the perimeter where your screed sticks will "ride"; firm in the field.

My opinion; worth price charged.

[Jake20]

Thank you, appreciate it.

Just out of curiosity, why do we add the extra sand to the sand topping mix? I plan on doing this for the 2nd mortar bed based on the above responses.

[Tool Guy - Kg]

To improve its workability. It’ll screed off nicer when it’s leaned-out and less sticky/clumpy.

[cx]

And be more porous.

My opinion; worth price charged.

[Jake20]

Is #6 accurate? I’m doing a shower floor and probably wouldn’t have gotten to the tiling anyway within that window.

[Jake20]

Guess the image didn’t upload. It was from the Sakrete site, stating that “tiling should begin within 16 hours of mortar bed installation. After 24 hours the mortar bed enters a “green state” and cannot have tile adhered for 28 days.”

[cx]

Jake, it'll help if you'll keep all your project questions on one thread so folks can see what you're working on and what's been previously asked and answered. A moderator can give it a more generic title any time you'd like to suggest one.

I'm not sure just what Sackrete product you're using nor just what they might mean by that wording. Perhaps you could provide a link to the product?

[Jake20]

Sorry about that. Will do for next time with the thread.

Here's the link:

https://www.sakrete.com/project-guid...-a-shower-pan/

I'm using Quikrete Sand Topping Mix. I didn't know if this was a general rule or specific to the Sakrete product. It's #6 at the very bottom.

Thank you.