# large tile 16"+



## MinConst (Oct 16, 2004)

I read something here the other day right after I tiles a small bathroom slab floor with 16" tiles. I don't do allot of tile floors so I have much to learn. I hear hollow under a couple tiles. I tried leveling the floor with the thinset the best I could but I don't think it was good enough. The slab wasn't off by much. But this hollow sound bothers me. I walked the tiles and jumped on the hollow sounding spots no cracks or anything.
I guess I need to know how to overcome this sort of issue. This floor will be in my mind for years now :sad:


----------



## JazMan (Feb 16, 2007)

You overcome it by starting with a flat floor, doesn't have to be level, but flat. Once it's plane is within 1/4" in 10 ft. you need to make sure you're using the proper notched trowel for the particular characteristics of the tiles. *What trowel did you use?* You should always double check for thinset transfer every once in a while, especially in the start. You want at least 85% transfer for interior tilling. 

Next you must make sure that the thinset in mixed to the right consistency. Nice and thick, but workable. It's got to hold its ridges once troweled without drooping. You need to 'burn' the thinset into the substrate with the flat side of the trowel, then spread more and comb the notched to leave the proper amount. The final notched should all go in one direction, (east & west) then when you set your tiles, you push and pull the tiles about 1/4" (north & south) to flatten the ridges. Doing it this way gives the best coverage.

And don't forget the thinset itself. *Which did you use?* For tiles of that size you should use a 'medium bed' thinset mortar type. The formulation is different and can also be applied thicker to help flatten the floor.

Jaz


----------



## MinConst (Oct 16, 2004)

I used a 1/4" trowel but premixed thinset. I do burn it in and then use the notch. I didn't lay a straight edge on the floor first but I don't think it was off by more than 1/4" in 10'. When I set the tile I twist it. Next time I will try north and south. That makes sense. I do run the notch east and west.


----------



## Forry (Feb 12, 2007)

By premixed "thinset", do you mean mastic? Mastic is no good, and especially for larger tiles... it can take months to completely dry.


----------



## JazMan (Feb 16, 2007)

Paul,

DO NOT sell any more tile jobs until you learn to use the right materials and tools.:thumbsup: First off as mentioned you cannot us anything that comes in a pail. Gotta use thinset mortar which only comes in powder. The people that make 'pre-mixed thinset' are lying. Be definition, thinset has to contain Portland. It is impossible to store mixed Portland in a pail. It is mastic and NO GOOD for floors or damp/wet areas. You can get away with using that stuff on dry wall areas. such as a kitchen backsplash. 

Also that trowel you used (1/4"), is not even close. Depending on its thickness and the texture of the backs, I recommend min. 1/4x3/8x1/4 but probably 1/4x1/2 or 1/2x1/2.:thumbup:

Jaz


----------



## MinConst (Oct 16, 2004)

JazMan said:


> Paul,
> 
> DO NOT sell any more tile jobs until you learn to use the right materials and toolsJaz


Thats why I asked the question, to learn. In my business I need to do what I need to do.


----------



## JazMan (Feb 16, 2007)

Yup, that's the way it is in almost every business. I'm sure you'll do very well in the future. Is there any chance of replacing those few tiles and re-setting them?

Part of the problem is the place you buy your materials I think. Probably one of the big box stores, where you're not likely to find anyone that knows much. Glad to see that you noticed the problem and want to learn how to avoid the same. I recommend you hang around here and read about products at their websites. Might be a good idea to get a TCNA (Tile Council of North America) handbook too. 

Jaz


----------



## MattCoops (Apr 7, 2006)

JazMan said:


> Gotta use thinset mortar which only comes in powder. The people that make 'pre-mixed thinset' are lying. Be definition, thinset has to contain Portland. It is impossible to store mixed Portland in a pail. It is mastic and NO GOOD for floors or damp/wet areas.
> 
> Jaz


I agree 100%.
I wish they didn't sell mastic.
I see no point in it for any kind of tile installation at all.
If it ever gets wet, even after the month it takes to dry, it will loosen and cause a mess.
To use it on a floor is ridiculous.
It takes no time at all to mix up a batch of thinset.
And it's cheaper to mix the proper thinset yourself.


To the original poster,
Your hollow sounding tiles are not covered 100% in thinset.
When you start to lay your tiles, slap one down and lift it up. Is it covered 100% in thinset? You may need to use a larger size trowel.
Being a 16" tile I probably would have started with a 1/4" x 3/16" notched trowel and see what the coverage was.

Those tiles probably will be fine over the years. Except for the annoying hollow sound. 
In any case, I would tear them out and set them down right after back-buttering the tile.


----------



## MinConst (Oct 16, 2004)

I will probably pull the two tiles and reset them this week. I have the time as the house is empty and there is plenty of time.
Thanks for the help. I will also checkout the TCNA handbook.


----------



## MattCoops (Apr 7, 2006)

TCA handbook is a must to have as a tile contractor


----------



## kevjob (Aug 14, 2006)

for more information try john bridge tile forum tell em' kevjob sent ya. You will learn more in one week with theses guys than weeks searching for yourself. :thumbsup:


----------



## MinConst (Oct 16, 2004)

I sent in an order for the TCA Handbook.
Will be stopping by the john bridge tile forum next. :thumbup:


----------



## Floordude (Aug 30, 2007)

I don't want to slam the guy, but this is what gives floorguys a bad rep.

When doing large format tiles, you better make darn sure the substrate is flat as a pane of glass.

Buy a good modified thinset. Flexbond work great for my needs.

I wouldn't use anything but a ½x½ notching on the trowel, and key it in real good.

Keep your comb lines all one direction, so when you plop the tile, all the air is expelled. You may bust a tile trying to get it out of the suction created, if you need to get the tile back out.

Invest in the Tuscon Leveling System, and never have a lipped tile job again.


----------



## Rich Turley (Apr 9, 2005)

Something I haven't seen anyone ask it the condition of the slab. If it had any kind of coating (paint, sealer, or anything) that could be interferring with the bond. You could've done everything else right (use thinset, back butter and all) and still have hollow tiles if the concrete is coated.


Rich

Just say no to mas...... I can't even type that word.


----------



## JazMan (Feb 16, 2007)

Hey Matt, you mentioning a 1/4x3/16 trowel surely must be a typo? 

Jaz


----------



## MinConst (Oct 16, 2004)

Rich Turley said:


> Something I haven't seen anyone ask it the condition of the slab. If it had any kind of coating (paint, sealer, or anything) that could be interferring with the bond. You could've done everything else right (use thinset, back butter and all) and still have hollow tiles if the concrete is coated.


 This brings up another question. I will be doing a small entryway in our own home. Not sure of tile size or type yet but I stained the floor last year with HC silicone acrylic stain. 2 coats. Do I need to strip this off before setting tile on the slab? I would imagine I will need to at least ruff it up. What steps should I take. Also I see using smaller tiles seems to cause less issues.
Thanks for the help here.
BTW I tested this bathroom slab by sprinkling water on the slab no beading just soaked in quickly.


----------



## MattCoops (Apr 7, 2006)

1/4 x *3/8*


----------



## Rich Turley (Apr 9, 2005)

Paul--

Kevjob's advice about TYW is right on, best place on the web to ask tile questions.

For your entry slab, yes get rid of the sealer. Much better to use mechanical means rather than strippers, which leave residue that can also interfer with the thinset bond. I'll use either a stiff wire brush wheel on my grinder or a concrete grinding wheel, particularly if any leveling needs to be done. 

Smaller tiles are easier to set and have less installation issues over large format tiles (to a point, mosiacs are a whole other issue), but added grout lines can be more of an issue down the road, particularly if you are using cement based grout. 

Rich


----------



## css (Jun 26, 2007)

MinConst said:


> I read something here the other day right after I tiles a small bathroom slab floor with 16" tiles. I don't do allot of tile floors so I have much to learn. I hear hollow under a couple tiles. I tried leveling the floor with the thinset the best I could but I don't think it was good enough. The slab wasn't off by much. But this hollow sound bothers me. I walked the tiles and jumped on the hollow sounding spots no cracks or anything.
> I guess I need to know how to overcome this sort of issue. This floor will be in my mind for years now :sad:


Again even if you did everything right (trowel size, backbutter,modified thinset, ) I have replaced several installations (not of my own) where the only interferance of the bond was a smooth troweled concrete. Even a modified thinset will release from a smooth troweled concrete over time.
Best choices are fracture membrane (ditra probably best. red gaurd ?,) My prefered method is bead blast or grinding to roughen surface. Might consider mega lite however not sure about that.


----------



## MinConst (Oct 16, 2004)

*Update on second bath*

I did the other bathroom today in he same 14" tile. Much better thanks to all the information I have gathered from you guys. I think the back buttering and east-west did the best. :clap:
Thanks. :notworthy


----------

