SteveBell wrote:

My client wants ceramic or porcelain tile on her back porch. The
previous owner had glue-down green carpet/fake grass there. My
question is: Can I put thinset down on top of the remaining skim
layer of carpet glue?

An Internet search gives me advice all over the map: remove it with
solvents/don't use solvents because they soak into the concrete and
keep thinset from sticking; remove it with abrasives/don't because it
just melts and wastes time; remove and replace an obscenely thick
layer (1/4 - 1/2 inch) of concrete.

* The surface is smooth and even, and it is sloped properly.
* I power-washed it awhile back, and the glue washed off just
slightly.
* I plan on scraping with a 4" razor in any case.

The fact that the glue dissolved slightly makes me hopeful that
water-based bedding material will "bond" with it. On the other hand,
it makes me worry, also, that it won't.

I'll take any advice I can get.

I power-washed the surface thoroughly yesterday, and that got off all
the loose stuff. I asked about this issue when I ordered the tile
today, and the tile-store guy called the manufacturer for me. They say
their thinset will stick just fine, as long as I put down a complete
layer.

Huh. Who doesn't put down a complete layer?

I have some RedGard left in the garage, so I'm thinking of donating it
to this project to seal the glue. The tile-store guy said it's a good
idea, but he'd be happy to sell me his competing brand....

--
Steve Bell
New Life Home Improvement
Arlington, TX