Tile prep: isolation membrane over painted and striped concrete
I'm in the process of prepping a concrete floor for ceramic tile. Floor is 50+ year old concrete that was previously painted (most likely with epoxy paint). I've used a chemical striper (water based) to remove most of the paint. There are areas that are very well adhered and still holding fast after multiple applications. Other areas where the paint was less well adhered that are now bare concrete. There is some cracking in the floor - mostly hairline to 1/16 with one crack that might be slightly wider. I'm looking for suggestions on crack isolation and prep. Most membranes out there donít allow application over chemically striped concrete. Unfortunately scarification is not an option - flooring is in a finished basement so dust and getting heavy machinery to the site would be a major issue if not completely prohibitive. Any suggestions on getting this area prepped? Do I even need a membrane or could I use a flexible thinset, eg Flexbond. I've heard a suggestion of embedding fiberglass to 6" to either side of the crack in the thinset would be enough.
Re: Tile prep: isolation membrane over painted and striped concrete
Personally since the underlying concrete is already in poor condition, would it be a possibility to do a concrete coating/epoxy in your weak areas prior to applying your thinset and mesh?