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Piney 10-13-2006 10:08 AM

Tile over Tile ??

Small bathroom remodel (4x6ft floor only).

Original tile is set over concrete floor. After several wacks with a hammer and chiisel, we determined moving it is going to be a huge pain !!

Sooooooo-- How does one go about installing new tile over old tile ?

One tile store said they would put down a layer of material (thinset of some sort) to level the existing tile, filling in the existing grout lines. Then lay thinset and new tile over this new surface.

Another store said they clean the existing tile, rough it with a sander, then just lay the new tile right over the old tile, with a slightly thicker layer of thinset (actually he used another term for a different setting material).

Comments ??

dougrus 10-13-2006 10:32 AM

Both suggestions are options...
First of all, you need to determine if it truly is a "concrete floor" the tile is set on...Is you house on a slab? If not then the floor you describe would be most likely a mortar bed, which may or may not be in good enough condition to tile over.
Second, although it is better not to tile over tile you can as long as you use good materials. Buy a GOOD modified thinset and either:

1. sand the surface of the old tile and lay the tile being sure to really "burn in" the thinset before you lay it with the flat side of other words, make sure you get the thinset really well adhered onto the old tile, then "comb" a layer in with the notched side of the trowel. and then be sure to "backbutter" the tile before you set it....
2. "Skim coat" the original tile with thinset, let it cure, and then thinset and tile over that after...the point is to level off the surface for the tile...

I have done a couple tile over tile in my house and one in my dads house...I just sanded the surface well and then just layed the tile...ALthough, If your floor is bumpy and has minor dips you can fill them with a skim coat.


Hope that helps....:)

J187 10-13-2006 12:39 PM

Piney, I very recently tiled over the old tile in bathroom. Two things to definitley consider

1. is the existing tile in good shape, are in any tiles loose?
2. how will the new height effect the room, ie you will probably need to extend the closet flange for the toilet, maybe cut the bottom of doors, raise vanities, and account for a new height difference at the transition point between the room and the hall.

I recently tiled over my old tile which was in perfect condition. I hope you didn't do any damage when you first tried to remove the old. I used a nice modified thinset and simply cleaned and scuffed the old tiles, applied my thinset like usual and tiled. I strongly recomend you get your tiles and thinset from a tile store rather than a big box home improvement store. The stronger tiles and better thinset will greatly aid your project.

LanterDan 10-13-2006 12:45 PM

If you did decide to take another crack at removing the old tile, I have heard (although not personally tried) that those air chisles that you can buy for under $20 work very well for this. This does require to you to have, or be able to borrow, an air compressor. Try to chisel underneath a tile and pop it up. Getting it started so you can do this will probably be the hardest part.

J187 10-13-2006 12:48 PM

If its a mortar bed, you'd have to be willing to do some work to that after removing the tiles, chances are pretty good something will need to be done. You may have better luck just going right over the old. If the old tiles are solid, its perfectly fine.

dougrus 10-13-2006 12:50 PM

Agreed on all points....

Changing all the heights can be a pain. Toilet flange you can get a flange extender but for thresholds and door casings, you have to do some cutting and/or removing.
Make sure you email back and let us know what is really under the floor and what condition the tiles are now in...As J187 said, tiling over a solid, non-moving floor is essential.
HD does have crappy tiles so go to a tile store as J187 said...
Although if you do need to buy modified thinset from there for whatever reason, the Versabond is a very good modified thinset.

dougrus 10-13-2006 12:55 PM

If it IS a mortar bed it would be somewhat difficult to get that tile up without cracking or damaging the bed and then, likely you will be looking at some serious demo to get that floor up...Ive done it a few times and it is no picnic.

Piney 10-13-2006 02:57 PM


Thanks for all the advise--

== The original tile IS on concrete slab flooring, as is the rest of the house.

== The original is definitely STUCK well-- none loose and quite difficult to chip loose. I tried this on a tile that would go under a new vanity-- no way its coming up with even moderate force.

Regarding problems with the additional height-- I can add an extension to the toilet flange. We're replacing the vanity anyway so that's not an issue.

DecksEtc 10-20-2006 09:41 PM


Originally Posted by LanterDan (Post 20723)
If you did decide to take another crack at removing the old tile, I have heard (although not personally tried) that those air chisles that you can buy for under $20 work very well for this. This does require to you to have, or be able to borrow, an air compressor. Try to chisel underneath a tile and pop it up. Getting it started so you can do this will probably be the hardest part.

An air chisel works well for this type of problem. It's a slow process but it does work.

dre2142 10-22-2006 10:03 AM

Getting under the 1st tile is the hardest part. After that, if you get under the tiles and theyll all pop up....once we got to that point, we realized taht if we went down to the bottom, an entire portion would pop up all at once.

Lucky for us, we had this at our disposle.

Piney 12-10-2006 07:27 PM


I"ve been able to get most all of the vinyl adhesive off via scraping and paint thinner and elbow grease (and a little:censored: )

Folks have said to sand the tile so that the new adhesive/mastic will stick to it under the new tile.

QUESTION-- About sanding. I took my belt sander and put on a #80 belt rated for tile/cement. It dulled the surface some, but not a lot IMO.
How much of a rough surface is needed ?
Should I use a grinder or something similar ?

QUESTION-- About cleaning. I used paint thinner to dissolve the glue. How clean does the tile surface need to be.
Should I go over the surface with some other cleaner ?

THanks !!

joefrog 08-06-2011 03:12 PM

Hey guys,

I'm doing the same project. The tile is in a small bathroom on the second floor, and it IS on a mortar bed.

I'm not sure what to do either! Break up the mortar bed, or lay right over this tile?

oh'mike 08-06-2011 06:53 PM

This topic was discussed in two recent posts---Tile can be installed over existing tile if the tile is stable and properly installed---Clean and scuff the old tile--an angle grinder fitted with 30 grit sand paper works well

Best to use an unmodified thinset mixed with liquid latex to set the new tiles--Kerabond and Keralastic is a good example of this.

morlaine 11-17-2011 08:08 PM

Installing Tile over Tile with Plasterbond
I need some help here. I've done some small decorative tile jobs around doorways that turned out pretty well. However, I've never done any floor tile. First I should tell you that I live in Costa Rica and choices of products to use are EXTREMELY limited. Think 1950. I had new tile installed about three years ago. The guy installed it over the old tile which I didn't realize he was going to do until it was half finished. Now there is a 10 x 12 section in the center of my living room that has come loose. It started out being about 7 x 9 but today I removed all the loose tiles and removed extra back to where the remaining tiles are firmly attached to the tile underneath. It looks like this guy put about a tablespoon of thinset or whatever he used under the tiles which is probably why they came loose. The tile I'm having to replace has been discontinued, of course. So I am opting to put down tile of a different color so it looks like a large area rug design. But I still have to lay it over the original tile.

I'm thinking of doing this job myself because I can't find competent workers here, whether it's tile, plumbling, electrical, or anything else.
Another thing that makes it difficult is that all conversations are in Spanish which I'm not fluent in. So that makes it difficult to ask these questions of anyone in a tile store.

So here is what I'm thinking of doing. Please point out any mistakes I'm making. Like I said, I've never done this before.
1. I've removed all the loose tiles.
2. I still need to remove some remaining stubborn hardened thinset, but trust me, there isn't much of that. I'm using a hammer and screwdriver, very tedious.
3. Should I clean the original tile with muriatic acid or something harsh like that? I want to make sure I don't have this problem again. I don't want to have to sand it as I would have to do that by hand.
4. Then from what people at the tile place said I need to put down a coat of Plasterbond. It's blue stuff with a consistency about like salad dressing in a bottle. Has anyone used it before? Does it need to dry before I put the thinset down? I haven't found a reference on the internet to it being used for tile but it seems to be commonly used here.
5. From reading on the internet I'm confused about what is Modified and Unmodified thinset. Can someone explain that to me? And which should I be using and why? I can't guarantee I'll be able to find it, but I'll look.
6. Sorry, I'm such a novice but do I just spread the thinset on the back of the tile like frosting a cake or do I have to put the streaks through it? Is that called combing? And what is the purpose of that?
7. And I cover the entire tile, right? Not just the center or the edges?
8. Then I put the tile down on the floor, right? Do I wiggle it around and press it down at the same time to get a good connection?
9. If you don't want to answer all these questions, is there a website where they could give me a detailed step by step procedure?
Thanks for any help you can give me. Carole (morlaine)

oh'mike 11-17-2011 08:56 PM

"Mud" What Is It? - Kitchen & Bath Remodeling - DIY Chatroom - DIY Home Improvement Forum

This explains thinset very well---in a nutshell--unmodified=just cement and sand--surface must be ideal to use this--

Modified--has powdered latex in the bag and sticks very well over most surfaces

Liquid latex added to unmodified ===stickiest of the three--best for tile over tile--

Muriatic acid---do not do that---the acid will clean the face of the tile---but --if it gets under the tile it will weaken the old thinset and could cause a failure of the old tile--

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