self leveling compound question

[Jackman]

I just removed the very old vinyl tile from my 1930s 400 sq/ft guesthouse. The floor has the black adhesive remaining. The floor is an old concrete slab with a few minor low spots. Is there any reason why I wouldn't want to pour a SLC on top of this or am I better off just skimming it with thinset? By the way I plan to lay tile for the new floor. Thanks.

[jadnashua]

Use a razor scraper to clean off as much of the adhesive as you can. Then carefully measure how extensive the dips you want to level are. Thinset is cheaper, slc is faster and more expensive, but it might be a wash when you add in your time and effort. Get a good handle on the extent of the problem first, though. A long straightedge will make fairly quick work of the investigation.

Pour some water on the surface and see if it is absorbed or beads up. If it beads up, you'll need to do some more work.