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tns1 09-21-2013 03:43 PM

Bathroom tile - slab leveling & crack control
I am re-tiling my small bathroom (50sq ft). The old tile & grout had no cracks. After pulling up the old 12" tile I see that the concrete slab does have several thin but long cracks. Also the floor is out of level by about 1/2" max, mostly in one corner. Since I am planning on large format 16x32 tile, I want to address the slab cracks & level issues.

I see there are some 2-part crack epoxies such as Emecole 555 or Spall Hi-Tech, which I could apply first. I am sure it does not hurt to use them, but if I use a crack control membrane, are they really necessary?

As far as I can tell the old tile work did not use any membrane or crack control method other than maybe they used a flex-bond type mortar. I was thinking of either using flex-bond mortar with some crack control fabric just over the cracks I have, or using a full floor fabric such as Ditra with regular
thin-set (versa-bond). Does this seem reasonable?

For leveling, there are many posts that talk about using SLC, yet folks using it never seem to get a good result the first time. It always takes a 2nd pour, or they have to live with something that isn't really level. I know of a couple of tile guys that just start at the high point and carefully level each tile as it is placed using mortar. It is possible they use a flex-bond type mortar, but they claim to have no call backs for tile cracking. I don't want to make my small-area project more complicated than it needs to be, and using a mortar that give you lots of working time and can be done in sections, is more attractive than the "rush-rush or you're screwed" SLC method. I suppose it comes down to whether you feel more comfortable
leveling tiles as you set them or working with a new product that has a learning curve.

Your thoughts are welcome.

Fix'n it 09-22-2013 11:35 AM

I wouldn't worry a bit about the crack/s.

i would use tile setting mortar to level. do thin layers and work your way too level.
i have done this, and it worked well.

i have also leveled as i tiled. but its was kind of a pita.

Blondesense 09-24-2013 01:29 AM

Is that 16 inch by 32 inch?!? Good grief, that is a big tile!
Have you done much tiling?
With tiles of this size flat is essential or you will have problems.

I'm not too experienced, having done all of three tile jobs so I won't try to answer your other questions, but FWIW, I had minor lippage problems just setting 13'x13" tiles. People who are not experienced setting tile may think that the bigger tile would be easier, after all, there would be less of them, but the opposite is true. Smaller tiles are more forgiving.

Unless you are experienced, I would think twice about tiles that size. And if you have your mind made up, look into one of the tile leveling systems. LASH is one, Tuscan is another, there are others out there.

I would not touch that size tile without one of them.

Edited to add: There are some experienced tile guys here who could answer your questions, but I think they may miss this thread since it is in the flooring section. You might ask the mods to move it to the tiling forum.

wkearney99 09-24-2013 05:53 AM

Seriously, let's hope that's centimeters not inches. Otherwise just wrestling those tiles around is going to be a back-breaking adventure. I just had some 24x24" tiles laid and they were no small challenge. Lippage is definitely a concern depending on how you plan on laying them out.

If you're going to use a membrane then do the whole floor. Otherwise I'd think you're just asking for the trouble to move to wherever the membrane stops.

oh'mike 09-24-2013 07:14 AM

You will need to use a leveling system with big ties like that----

tns1 09-24-2013 01:05 PM

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Yes, that is 16" x 31" tile. I wish it was available smaller. It took a long time for the tile picker to make up her mind, so I'd like to make this work if I can. On the plus side, I would only need 16 tiles to cover the area (see pic). This tile has a mat finish with slight texture which I thought would help blend any non-level issues. As a diy project, we are not really after museum quality finish, I am more concerned about cracking.

I was not aware that larger tile would present a bigger lippage issue. The first step to controlling this is to level the floor, which I am working on. The Rubi or Tuscan systems look like good products. The downside is it looks like you have to do the entire floor in one session, and cannot cut & fit a few tiles at a time.

wkearney99 09-24-2013 01:43 PM

Not to complicate matters, but just WHAT is that tile that other solutions cannot be found?

Having just gone through picking tiles, accents, counters and stone for a house I can say I've seen QUITE a few selections. And seen many overlaps in styles and alternatives from different vendors.

I made it a habit to have a specific idea in mind but then run it past the salesmen and installers to weigh in on the cost-effectiveness and installability of it. For a few I switched to either a much more cost-effective choice or one that would be a lot less hassle to install. As in, in-stock glass pencils vs imported Sicis tiles. Or an overstock of a large format instead of a similar 12x12". The end results looked very much the same but at a savings of around $3k in materials alone.

The important question to ask about that tile is whether it's rectified, as that will reduce (but not eliminate) some lippage issues. But also ask how thick each piece averages. Larger tiles are often a lot thicker and this can pose problems for making clean transitions at entries. This really matter when you start putting heated flooring under it along with membrane.

tns1 09-24-2013 03:36 PM

The tile is Eramosa Avorio.
It is porcelain but the sample I have has a formed edge, so not rectified I think. I do see another Eramosa porcelain in 12x24" white color. A similar pattern, but since it is a different factory, I'd have to get a sample to know about color & texture. As I said I'm not the tile picker in this. I have the whip marks to show where I fit in the grand scheme.

True Eramosa would be cut stone, so taking the 40x80cm & cutting it into quarters would actually be a closer facsimile to the real thing, and make it easier to work with. A lot of cutting though.

oh'mike 09-24-2013 03:42 PM

Take a straight edge and check the tile for flatness--You will be renting a bridge saw for this one?

tns1 10-08-2013 07:27 PM

I have leveled the floor using thinset. I was able to form a few criss-crossing dikes of material that I sanded until level. I used these to screed on thinset in layers. Sliding an aluminum straight edge on the dried surface marked the high spots that I hand sanded with 60 grit. It was only took about 1 bag, but took several days due to necessary drying time and number of layers. I believe the flatness matches what I would have achieved as a first time SLC user.

The tile sample I have is only a partial, so I can't judge the flatness. I am told there is a bow to each tile that favors a stagger pattern of no more than 25%. With my layout, it looks like all the cut edges would be up against the wall & covered with baseboard or other trim even if I didn't have perfect edges.

The saw I am using is a 24" rolling table style. For longer cuts it looks like I could just flip the tile, but since I have few unique cuts I was thinking I could just make a wooden table-top for the saw with a fence. That way, I should be able to saw any length as long as I have a way to catch the water. What other advantage does a bridge saw have anyway?

tns1 11-16-2013 11:50 PM

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I ended up changing the tile pattern to 45deg with 50% overlap. This presented some difficulties when setting the tile, but actually made it easier to cut. I attached a large piece of plywood to my tile saw to support the larger tiles. I laid another piece of plywood on top of this to act as a sliding surface. I used a fixed 45deg fence on top to get the tile at the proper angle. I was able to saw more than half way thru the tile, spin it 180 and saw the rest of the way. It worked well, and saved me from renting a bigger saw.

For setting the tile, I planned on using the LASH straps, but I only had 9 full tiles to set plus several half tiles. I expected to work very slowly and it didn't look like the leveling system would work very well unless I could set all the field tiles at once. I was also put off by the large curve on the bases, which is not going to allow final mortar height until the wedges are cinched down. I didn't use them.

I mixed and set 2 or 3 tiles at a time, using the Megalite mortar, and checked frequently for flatness & alignment. It is hard to do a good troweling job when all you have are triangular areas up against a wall. Anyway, I am satisfied with the result. There is some lippage where the centers of the long tiles are next to the corners of adjacent tiles, but I knew that might happen. With 3/16 grout lines and textured tiles, I think it will not be noticeable.

Is it more common to grout the joints near the wall, or is caulk used for expansion? These areas will be covered with baseboard.

Fix'n it 11-17-2013 08:41 AM


Originally Posted by tns1 (Post 1267533)

Is it more common to grout the joints near the wall, or is caulk used for expansion? These areas will be covered with baseboard.

if under baseboard/whatever. don't bother putting anything.

tns1 11-17-2013 12:14 PM

I am thinking since it is a bathroom, I'd want the grout lines near the wall filled with something to help keep spilled water from going into the wall. Yes, I do plan to use caulk on the baseboard, but figured this would be extra protection.

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