Tile Over Concrete

stringblade

Just recently purchased a new home its a single story slab house.
I am interested in putting ceramic tile in a few areas i have never done tiling directly over concrete before ive always used hardi backer. my concerns are there were vinal tiles used all throughout the house, ive scraped them off there is still a glue residue left on the floor. does this have to come off? what is the best way to go about this? what type of thinset do i use when applying tiles directly to concrete slab?

Thanks just want to do things right the first time.....

R&D Tile

Seeing it's a new home, doubt it's cutback adhesive, it's not black is it?

In any case try some hot water on the glue and see if it softens up any and scrape up what you can, do not use and chemical strippers, as long as the slab is flat and has no cracks, you can use a good modified thinset for this, Flexbond from HD is easy to get and works fine for this.

A crack isolation membrane cost more to install first, but that's up to you, just added insurance in case any cracks develop in the future in that slab.

Floorwizard

I would even venture to say "When the cracks occur"

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Teetorbilt

Ditto on the cracks. All too common anymore.

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stringblade

it is a black adhesive what does this mean?? do i want to know??

R&D Tile

How old is this new home?

stringblade

about 50 years

Bill_Vincent

Not really. Most likely, it contains asbestos. Now for the good news-- asbestos is only dangerous if it becomes airborn, and all you really need to do is with a 4" razor scraper, scrape as much as you can off the concrete, and then use a high latex content modified thinset to set your tile. Although it's not very probable that you'll put any asbestos into the air by scraping it, I would still highly advise that you use a filter respirator and gloves, just to be safe.

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ee3

also you can keep the dust down with water if possible.

R&D Tile

Those 9" tile you scraped up had most of the asbestos.

Anyway, don't grind this stuff, hit any thick spots with the back of a hammer or masons hammer or chisle, if it doesn't chip up just leave it and do as Bill said.

Flexbond works well over cutback adhesive and is easy to get at HD.

Any cracks in the slab?

If so, ee3 will advise on which membrane to use over this.

R&D Tile

Does the floor look like this?, that's cutback.

Attached Thumbnails

 

stringblade

Yes R/D the adhesive does look exactly like that in the picture. they had tiled and sheet rocked the entire house then framed the walls. makes it a real pain in the ass to work with.
thanks for your help

Zero Punch

Take it for what it's worth. When I was an apprentice about 40 years ago, one of the journeymen told of being given 2 lot numbers and told to tile those two homes. When he arrived there were two slabs with Asphalt tile, cutback, and a diagram sitting in a pile in the carport. He swept them spread them both up tiled them and was done by noon. I always though it was BS, but ???? That 1/8 Asphalt and even VAT over cutback would cover a multitude of sins.

Bill_Vincent

This copied and pasted from my website in response to the last post:

This is a subject that's very hotly debated within the industry. It seems every manufacturer has a thinset that they say can be used over resilient flooring (sheet vinyl) or vinyl tile. The problem with that is twofold. With all the different types of vinyl flooring out now, it's tough to know which ones can, and which ones can't be tiled over. Cushioned vinyl's are out. They can compress, causing voids under the tile, ultimately causing failure. Also, not all sheet vinyl is glued solid to the floor. A lot of times, vinyl installers will only glue the edges and spot glue in the center, and if you thinset the tile to it, it won't stay very long. In my opinion, vinyl tiles are out, as well, due to the fact that the thinset bond is only as good as the bond of the surface under it, and I've seen vinyl tiles ( especially peel and stick) let go way too easily. The same is also true for sheet vinyl. The second problem with tiling over vinyl is the underlayments used for vinyl installation. Normally, in woodframe construction, there are one of several underlayments used-- luan, 1/4" particle board, 1/4" plywood, and sometimes even MDF (medium density fiberboard). ANY of those in a tile subfloor is a guaranteed failure. 1/4" plywood has a nasty habit of delaminating (the layers come apart). Luan has the same problem, plus it can compress to 1/2 its original thickness from normal residential foot traffic (I've seen this happen). Particle board (as well as MDF), just from humidity, can expand enough to pop tile loose. Any of those can cause failure, and unless you pull the vinyl, you don't know for sure whether the vinyl installer just went over the existing subfloor, or added one of the underlayments mentioned. All in all, it's an extremely risky installation, and my question is why, when spending the money it costs for a tile installation, would you want to gamble on it?

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"Whether you think you can, or you think you can't, you're probably right."

http://www.creativeceramicandmarble.com

Floorwizard

good post.
it says EVERYTHING.

__________________
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"in 20 years you will regret more what you did not do than what you did"