Good afternoon,

I have tiles installed over concrete through a good portion of the first floor of my house. I recently found out the unpleasant way that the original installation job was less than optimal and the tiles had no adhesion to the concrete in the kitchen area. The original tile shop suggested that the installers probably cut corners during the installation and overspray from the kitchen cabinets effectively sealed the concrete and prevented a bond but 12 years after the fact they care very little. Sure enough the mortar attached firmly to the tiles but not at all to the areas of concrete that are stained brown. I would say the installers did scrape the varnish off, except fot the bits they missed, but did not get the stain out. The tiles in other ares are stuck down very well and are taking more effort than I though possible to remove. I have decided to use this event as the jumping point to install glue down engineered wood floorring.

So to the first round of questions

1. Is wood stain sufficient to break the mortar bond? If so will it also break the leveler/moisture barrier/glue bond?
2. Assuming it will, is there a chemical treatment that will leech the stain out of the concrete and open the surface for a skim coat?
3. If not, how much of the surface should I grind away? Is it enough to rough the surface up?
4. For this and the high spot grinding process I am planning on using a diamond cup (4" - It’s a DIY job); probably several. Can anyone recommend a brand or style (single row, dual row, turbo)? What about grit grade?
5. What is the life expectancy in grinding minutes (?) of the diamond cups that people have used.

Thank you,
Kevin Shore
Austin, TX.

Unfortunately, if the amount of overspray cause failure of the mortar bond then it will most likely be sufficient to break the bond for any leveling compound. As to a moisture membrane, or wood glue. These bonds might or might not be affected.


I purchased a single and a double row dry diamond grinding cup and the have lasted for ever. the double row cup cuts a bit faster. If you can find a grinder with dust collection capabilities you will be happier. I found a reconditioned porter cable with a dust port. I paid an arm and a leg but it is virtually dust free when hooked to a shop vac equiped with a super fine vacuum bag.

As far as how much to take off. When you put drops of water on the concrete they should absorb not bead up.

Barquios,

Thank you for the reply. Unless someone can tell me about a chemical treatment I will grind the surface. The dust created by the tile removal has already covered everything in my house and I'm only about 10% finished with that phase so a little more dust from grinding will not be a big ussue.

Thanks,
Kevin Shore
Austin, TX.

No, don't use a chemical. It will become a bond breaker for the new adhesive.