How To Prep For Ceramic Where VCT Was

jimb317

I removed some old VCT from a concrete floor and it left some of the backing down. What is required to clean, prep the floor to lay new ceramic. There is also a crack in the concrete where the floor rose a 1/8" .

Mike Costello

VCT doesnt have a backing. Do you mean black adhesive residue?

R&D Tile

Is this crack even on each side, in other words, is the floor higher on one side of the crack?

jimb317

Yes black adhesive residue. I would assume you have to remove this so the ceramic has a good bond to the concrete.
The crack is a bit higher on one side, about an 1/8"-1/4" what is the best way to level this?

Bud Cline

How long has that crack been like that (higher on one side)?

A crack and upheival like that would have been easily noticeable through the vinyl tile. Chances are there is no fixing it to suit ceramic tile.

jimb317

I dont know how long the crack has been there. It's at a friends house that they just bought, they removed a carpet in a breezeway and want to put ceramic down. When we lifted the carpet we found the VCT and the crack. The VCT was removed with a scraper and left behind the black adhesive residue.
I was thinking he could put some floor leveler down and then just hope it is a few years until the tile cracks if the floor moves more.
What is our best bet with the residue?
What do we do with the crack issue?

Tileworks

Physically removing all the residue is the most reliable way to make sure you have an appropriate surface to which to bond tile. However, old "cut-back" adhesive can be very difficult to remove. Nowadays, most mortar manufacturers make a thinset which will bond to "cut back" adhesive.

Scrape the adhesive so the tile is not sitting on ridges. The "cut-back" adhesive also must made from asphaltic material and therefore not soften when exposed to water. So, throw a wet towel on an area and keep it wet for several hours and see if the material softens up. If the adhesive is softened by water, it's got to be removed entirely.

In regards to the crack, you can make up the difference with the thinset, perhaps even floating it out a day ahead of time if it makes you feel more comfortable. Use mesh tape at the very least over it, but as Bud Cline indicated, there will be nothing you can really do to prevent the tile above it from cracking should it decide to move again.

- Bob

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Classic Tileworks
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Ohio Tile and Stone Installation Contractor in the Akron area serving Summit, Portage, Medina, Stark, & Cuyahoga counties in Northeast Ohio

Mike Costello

That is an awsome idea with the towel.

jimb317

I will try the towel Idea. Thanks.
I assume you put the mesh down with the thinset.

Tileworks

Yes. You can do it ahead of time or as your tiling.

- Bob

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Classic Tileworks
http://www.classictileworks.com
Ohio Tile and Stone Installation Contractor in the Akron area serving Summit, Portage, Medina, Stark, & Cuyahoga counties in Northeast Ohio

jamestrd

they gots membrane for cracks,,

heres an easy idea.. shoot down 3/8 plywood or HB/durockand forget about cutback and crack..

the slab aint going nowhere anymore..it already moved and was probably due to ground water pressure., or the slab wasnt set properly, no drainage...

Floordude

Hehehe, Don't tell them what you removed was ASBESTOS VAT tiles, not VCT tiles, Don't tell them that the black adhesive is ASBESTOS cutback adhesive!!!! Don't tell them that the home is now contaminated with ASBESTOS dust!!!


Hehehehe!

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