Sign In to join the community | Help

Best tool to remove thinset from concrete

I have a bunch of ceramic tiles that have lifted up on my pool lanai. I have cut the grout and lifted the tiles, and now I need to remove the old thinset from the concrete. The area is too large to do with a hammer and cold chisel. What tool should I use to remove the thinset, but not damage the concrete? I also noticed that there is a crack in the concrete; should I patch the crack before laying new thinset? If yes, what is the proper material to use?


Last question: I was able to salvage several of the tiles, and was hoping to reuse them. They all have some thinset stuck to them, and the tiles will break if I try to chisel it off. Can I lay the tiles with old thinset on top of new thinset and expect them to stick?




Not what you were looking for ? Try posting a question
Posted 2012-01-16T17:49:53+0000  by kravnh kravnh

Using a SDS roto-hammer such as a Bosch Bulldog with a Tile Chisel Scraper attachment should do the trick. Both items are sold at HD.  And using tiles with the thinset on the back shoudn't be a problem, even though some might say otherwise.  As long as the thinset is on there good; however you might have a little more trouble leveling out the tiles when installing them due to the thinset on the back, but applying thinset to the concrete and then "back buttering" the tiles (means applying thinset to the back of the tile too) should help you have a little more play/wiggle room when installing the tiles.  This method also ensures a better bond. Good luck with your project! -Mark

Posted 2012-01-17T04:45:05+0000  by mgonzo

Welcome to the community Keith.


I agree with Mark SDS roto hammer with a Tile Chisel attachment its the way to go. And also just like Mark I don’t see a problem using tile with the thinset on the back of it.


The only suggestions I would add here is that you might be better of setting your tile in the mud bed second time around. This will give you more "meat" to level the tile and also it is, in my opinion, better method of setting tile in exterior applications. Mud bed its basically a "dry" mix of portland cement, sand and water.


As far as the crack in concrete goes that is a little bit more complicated. If this is just a small crack at the corner or something than YES, you can just patch the crack before laying new thinset. If this is an expansion crack running across, full width of the slab, than you should cut something called a control joint. Simple patch it is not going to fix the crack, that same crack it’s going to show again on the surface of the tile in no time. Solution is to honor that same crack by cutting a control joint(s).We carry some great products made by Schluter Systems for joint movements. See attached PDF and notice the mud bed detail that I’ve talked about.

Joint profiles.JPG

Hope this helps.



Posted 2012-01-17T15:11:31+0000  by George_HD_CHI

Mark and George, thank you both for your replies. I'll first check to see if my local HD rents a roto-hammer, as it is something that I probably will not use often enough to warrant the purchase price. 


Is mud bed a pre-mixed product I can purchase, or do I need to buy portland cement and sand, and mix it myself?


Finally, the crack travels quite a distance along the surface of the concrete, and is related to the house settling (it is now 6 years old). My worry is that the settling is not finished, and I will see this problem recur. 



Posted 2012-01-17T17:41:11+0000  by kravnh

You are welcome Keith.


Is mud bed a pre-mixed product I can purchase, or do I need to buy portland cement and sand, and mix it myself?


Yes, premixed version it’s available and it is called a SAND/TOPPING mix. See attached PDF;



You can also make your own mix. Formula is three parts of sand to one part of portland cement.

I've used both and my own mix was always a little bit darker than premixed stuff. I don’t know the exact ingredients of the premixed stuff ,but I think my mix has a little bit more of portland cement in it.


Anyhow I think both of these are going to work just fine.



There are two methods you can use to set the tile down with this stuff. One, you can set them down tile by tile trying  to keep the tiles leveled (hard due to thickness of the material)  or you can spread  the mix down ,screed the area, and install tiles on top of the “bed”.


With the first method you would mix the material “wet” almost to like mortar mix consistency used to lay brick.

With the second method  trick is to mix the material dry that it can be packed and screed and on the other hand to be wet enough that it can stand on its own and accept the tile to be set in.

A garden hose misting attachment (pistol) comes handy when mixing “dry” mix.


Mud bed should not be less than 1” thick. I use chain link line posts (1-5/8”) or an electrical conduit to keep the uniform thickness of the “bed”. Basically you would lay the pipe down, I keep them parallel  about 4’ feet apart, (that’s how far my hands can reach) spread and pack the mix in between the pipes and remove excess by pulling  a straight piece of 1x6” lumber in back and forth motion on top of the pipes.

This is the only way to keep the area flat when you’re working on a large area. Keeping the area flat is crucial; ponding water is what’s making the tile separate from the substrate.


That’s not it.:)


You also need something called bonding agent.


I make my own by mixing straight portland cement and water to a milky consistency.


This bonding mixture it’s used to re wet the bed mix before you set the tile down.

Basically it reassures the good bond in between the mortar bed and the tile and it also makes easier laying the tile down.

Finally you are going to need a rubber mullet to set the tile in this “bed”, but once its set I don’t think you are going to have the same problem for a long time.



Posted 2012-01-17T20:23:11+0000  by George_HD_CHI



Thank you for the education on mud bed. Unfortunately, it will not work with this application. After removing the thinset, I will have less than 1" depth to work. I am not replacing tiles on the entire lanai; just a group of tiles that have come up. If I were re-tiling the entire surface, I could work with the mud bed and layer it as thick as needed.


This time around, I will reapply thinset, and back-butter the tiles, as Mark had suggested.


Thank you again for your help; I think this project is gonna be pretty easy .



Posted 2012-01-17T21:01:01+0000  by kravnh

That makes perfect sense Keith,


Good luck with your project and don’t forget to stop by the community once in a while.



Posted 2012-01-17T21:13:13+0000  by George_HD_CHI
Not what you were looking for ? Try posting a question