We are preparing our concrete floor to install ceramic tiles. Our problem is one-half of the concrete slab was once covered with indoor/outdoor carpet that was glued to the concrete. We have scraped off as much as we can; however, we feel the concrete should be clean for the thin-set to adhere. Is there a easy, non-toxic way to remove the residual adhesive?

As ong as the floor is smooth dont worry about any glue stain or if a thin layer is left behind. It should not be so high that it interferes with the tile lying flat. Get a good modified thinset that is rated for going over "cutback", the glue we are talking about. It will say so on the back of the bag. Make ther salesman show you it says that, dont take his word for it. Expect to pay about $20+ per 50lb bag. Mapei, Tec, Laticrete, Custom, and other names, all make specific thinsets that can do the job, but not every thinset in their product lines is rated to go over cutback.

make sure u get up all the loose glue, the thinset is only as good as what its glued to, so if the glue from the carpet is coming off easily the tiles will not have a strong bond.

also you might want to wet the glue and see f the glue breaks down, if it does make sure u get it all up before you tile over it or your thinset wont be doing sh!t

Thank you both for your suggestions. We tried a number of non-toxic solvents; however, ended up using Klen-Strip Adhesive remover. It was messy but I feel more confident about applying the thin set to the cleaned concrete.

TileGuyBob: I will check our thin set package for covering "cutback". It helps to know these things.

Have a great day.