How do we remove thinset?

Mountain Lady

New Member
Feb 14, 2015
36
North Carolina
We pulled up the tile in front of our fireplace and found thinset laid over 66 year old oak floor and a concrete hearth. A hammer and pry bar seem to slowly chip it up where it was laid on thickly. In areas of thinner application the prybar seems to skip over the thinset. Have you any suggestions on getting the thinset up without harming the wood floor and hearth?

image.jpg
 

DougA

Minister of Fire
Dec 13, 2012
1,938
S. ON
I would use a belt sander or orbital sander to have the least damage to the wood.
 
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Supersurvey

Burning Hunk
Jan 25, 2015
169
New Jersey
We pulled up the tile in front of our fireplace and found thinset laid over 66 year old oak floor and a concrete hearth. A hammer and pry bar seem to slowly chip it up where it was laid on thickly. In areas of thinner application the prybar seems to skip over the thinset. Have you any suggestions on getting the thinset up without harming the wood floor and hearth?

View attachment 154469
You could try an angle grinder but would have to be very careful.
 

David.Ervin

Burning Hunk
Jan 17, 2014
243
O-H
Some really old mortar uses asbestos as a binder. You probably don't want to go at it with a belt sander unless you're sure it's NOT that kind.
 

jatoxico

Minister of Fire
Aug 8, 2011
4,067
Long Island NY
If there's a latex additive in the thinset the sandpaper can get gummed up. You can also clean the concrete (test it on the wood) with muriatic.
 

mstoelton

Feeling the Heat
Dec 16, 2013
486
SE michigan
You could use a demo hammer with a "blade" type bit and use a low angle of attack to just get the thinset (rental from HD). If you are concerned about any asbestos, wet the thinset to minimize dust and do not use a vacuum for clean-up if there is a possible asbestos problem.

If you are really concerned about any asbestos, you can have the thinset tested at a lab for less than $50.
 

bluedogz

Minister of Fire
Oct 9, 2011
1,247
NE Maryland
You could use a demo hammer with a "blade" type bit and use a low angle of attack to just get the thinset (rental from HD). If you are concerned about any asbestos, wet the thinset to minimize dust and do not use a vacuum for clean-up if there is a possible asbestos problem.

If you are really concerned about any asbestos, you can have the thinset tested at a lab for less than $50.
I rented an electric demo hammer for such a purpose. Quite easy to use.

Younger/cheaper me might try a chisel. But don't forget the thinset is much harder than the oak floor, so "getting it up without damage" might be a losing game.
 
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bholler

Chimney sweep
Staff member
Jan 14, 2014
18,384
central pa
There isn't much there i have a demo hammer but i would probably use a hammer and chisel to keep the damage to a minimum. Then sand the last little bit away.
 
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jatoxico

Minister of Fire
Aug 8, 2011
4,067
Long Island NY
Given the flooring is finished under the thinset this looks like relatively recent work to me. More likely latex than asbestos but who knows? I would do more chipping and scraping with a sharp scraper than sanding myself.
 
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TheRambler

Feeling the Heat
Jul 29, 2014
478
CT
If your really concerned about asbestos you can always rent or buy a respirator from a local hardware store. I also vote for hammer and chisel and a belt or orbital sander. If your just going to retile or similar then you may not have to go too crazy getting it off. You want thr vast majority of it off, but dont have to go crazy with it.
 

Typ0

Feeling the Heat
Dec 18, 2014
351
Central New York
When I first glanced I thought "oh chit look at that beautiful floor to save" but upon further inspection the problem is mostly on concrete.

How deep is that hearth? Why don't you just cut out that little bit of hardwood effected and the hearth then repour it a little larger? I don't know what your skills are and that sounds like major construction but it's going to be a lot easier and will yield better results in the end. Put on top of that the asbestos potential and that's the rout I would be considering. If you are on a slab I would think you can chip out that hearth and put some nice stone down....
 

simple.serf

Feeling the Heat
Dec 7, 2011
336
Sherman, NY
A bosch sds hammerdrill with a chisel at a low angle would handle that in no time. I used to repair ceramic tile in a large commercial setting in my previous position. If you are worried about asbestos, just keep it wet.
 

Shari

Minister of Fire
Oct 31, 2008
2,327
Wisconsin
According to your avatar, you had one tile width out on your hearth before you started. Assuming that tile was a 12" tile you will have to widen your hearth for any new install (18" is code just about anywhere I believe) - so - forget about getting the thinset off as you will just be covering it up when you install the new hearth anyway.
 
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David.Ervin

Burning Hunk
Jan 17, 2014
243
O-H
forget about getting the thinset off as you will just be covering it up when you install the new hearth anyway.
Seconding this - if you can get the surrounding floor level-ish, drop some micore or durock on that as a base for your hearth and pretend the thinset doesn't exist.
 
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jb6l6gc

Minister of Fire
Feb 26, 2015
820
Cayuga, Ontario, Canada
I would try a oscillating tool, mine came with all sorts of cutter and scraper blades, as well as sanding pads all for $25
 

begreen

Mooderator
Staff member
Nov 18, 2005
78,080
South Puget Sound, WA
According to your avatar, you had one tile width out on your hearth before you started. Assuming that tile was a 12" tile you will have to widen your hearth for any new install (18" is code just about anywhere I believe) - so - forget about getting the thinset off as you will just be covering it up when you install the new hearth anyway.
Agreed. If the hearth is being extended for the stove and the floor surface is truly flush with the hearth, cover it with Durock and then tile. If it is not level then you may need to build up one surface or the other to get it to that point.
 

Mountain Lady

New Member
Feb 14, 2015
36
North Carolina
Hi All!

We found a few tools in the basement after seeing that our sander wasn't making a dent in the thinset. A putty knife did a nice job in some areas. A caulk remover is even better than a putty knife. My conclusion: a hammer and chisel is the best approach.

We believe that the tiling job is recent because there were barcodes on the back of the wood trim. They were in great shape. So, we assume no asbestos.

The installation plan is sorta in limbo right now. We wanted to go through the wall above the mantle, through the thimble that is there. Depending on whether we get single or double liner, we have to cut our wall around the thimble. It would be 18" around the thimble if we do single and ??" out from the thimble if we do a double walled liner. We only have 16 inches from the thimble to the ceiling and 16 inches from the thimble to the top of the mantle. We really would enjoy the radiant heat from a single walled liner AND it is more affordable. But, we would most love to avoid framing out the opening. And, really, covering the opening with cement board sounds like it will look out of place. So... We are waiting to hear if we can vent through the fireplace. The opening is 30" high so we are waiting to hear back if the F45 can be vented through a 30" high opening when sitting on a hearth pad.

Here is one of the quotes. We need to add a thimble to it since ours is busted. I'll post the other estimate later.
image.jpg
 
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begreen

Mooderator
Staff member
Nov 18, 2005
78,080
South Puget Sound, WA
Screen Shot 2015-02-26 at 2.49.28 PM.png
 

Mountain Lady

New Member
Feb 14, 2015
36
North Carolina
Here is the side where I've been working. This side had thinner thinset and it was hard to get a toe hold with the chisel. Again, sorry for the flipped view.
image.jpg
 
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Mountain Lady

New Member
Feb 14, 2015
36
North Carolina
image.jpg
Begreen, it says "hearth mount installation only" on that diagram. Our stove will be on a heart pad out in front of the fireplace opening. Thats why our tiles had to come up, to make the floor level. Is that a hearth mount?

Sorry for the flipped picture.
 
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begreen

Mooderator
Staff member
Nov 18, 2005
78,080
South Puget Sound, WA
No, hearth mount means the stove placed on the fireplace hearth. I wasn't sure if you were going to have the stove in the fireplace or not. It looks like there will be a problem then because the thickness of the height added due to the hearthpad thickness.
 
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