Flooring Tile - Is Mastic Removal Necessary before Tiling?

We will be tiling the bathroom floor in the near future and understand that we can't leave the vinyl flooring under the ceramic tile. There are two layers of vinyl over a concreted slab and we are assuming the vinyl was installed with mastic glue. Is is necessary to get all this off the concrete slab before putting down the thinset? If so, what product is made for this job since I doubt a putty knife will work?

Any help you can provide will be most appreciated since this will be our first effort at this. Thanks!

A 4" razor scraper and some warm water will work. Chemical adhesive removers can cause bond failure of any future flooring installed in the area in question.

A 4" razor scraper and some warm water will work. Chemical adhesive removers can cause bond failure of any future flooring installed in the area in question.

I have 2 thoughts on this:

Be very sure about your assumption "assuming the vinyl was installed with mastic glue". Some glues like old black cutback adhesive typically contain asbestos. Scraping an asbestos adhesive incorrectly will put you and your family at risk.

While it's true about the chemical bond issue, I used Sentinel 747 on a slab I'm going to tile and then tested concrete absorption be seeing how fast water saturates. I haven't laid the tiles yet, but I'm confident that in my case there is no chemical adhesion issue.

Good luck! :thumbup:

When we faced that situation, we used a flat shovel (this can even be sharpened) to scrape away the old tile adhesive. I believe there are also tools for this purpose that can be rented. It's much faster than using a small bladed tool. Plus, its easier on the back since it elimates most of the kneeling. Beware of asbestos if the original flooring was older than 20 years or so.