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scanale42 03-05-2012 12:20 PM

Tiling over old adhesive
So we have a house from the 50's that had 4 floors in the kitchen. the top layer was a floating floor that was installed by me about 10 years ago when I was inexperienced. The next to levels were a vinyl tile that just had a sticky back that came up relatively easy. The last layer was a diamond shaped tile that looks like it was installed when the house was built that has a black tar like adhesive over the concrete slab.

Ultimately, I'd like to install a ceramic tile on top of the slab. To compound the issue, I have a raised area in the center of the floor that appears to be somehow be caused by the concrete and not the adhesive layers.

My thought was to apply a SLC to level, and then use one of those thinsets that is supposed to be good over cutback adhesive(I've done some research and heard this term used, but I'm not sure if this is cutback adhesive or not). But I have concerns about the SLC not sticking to the adhesive.

If this isn't possible, could I just run a straight line across the floor taking account the height that I want the tile to be and the low spots, and just put in more mortar in the low spots?

Lastly, I'm also considering having someone else take care of this for me, but I was wondering if anyone knew what the labor would cost to have someone reliably lay about 200 sq feet of tile on this floor of mine so that it ultimately level? I understand it can vary, so ball park is fine.

JazMan 03-05-2012 06:33 PM

You might be able to lower the peak instead of raising the entire valley. Using SLC is usually not the right answer in cases like yours.

You need to analyze the contours of your floor and how much higher the high spots is. Let's start with a good description of that.


JetSwet 03-05-2012 07:13 PM

Post up a photo if you can.
You mentioned this is a slab correct?
If so there will be next to nothing that you can do about the center being higher, how much of a dip on the sides is there?
If the sides aren't that off from the top maybe a slc or you can morter the sides to level.

scanale42 03-06-2012 12:36 PM

Thanks for the responses. I'll try and take a couple of pictures later tonight and post them. I'll get a close up of the adhesive and where it meets the concrete, and I'll get one with a level on the uneven portion and measure the lowest valley.

Essentially what we have is a 20x10 foot space. About half of it is dedicated to the kitchen area. About 10 feet to the right, we have a small room that hides the furnace, and the laundry room on the far side.

So the main kitchen area is primarily contained in a 10'x10' space and the uneveness is pretty much only located there.

There is a peak running perpendicular to the doorway to the kitchen that seems to run about 6 feet long before leveling out, and a valley on either side of it. The edges of the kitchen, on either side of the valleys level out again. So as a crude layout, it would look something like this:


So the L's are level, the V's are valleys, and the P's are the peak. Like I said, I'll try and get a couple of pictures

JazMan 03-06-2012 03:23 PM

Forget the level, we don't care about level that much, the tile cares about flat not level. A 4' level isn't long enough to be of much help.

Get a long straight edge to determine how to proceed. I would say a 10' straight edge is good enough. Otherwise you can use string or laser.

Waiting for the pics and another description.


JetSwet 03-06-2012 04:28 PM

And just as what the op has posted with the p,v and L the floor is not flat by any means.

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