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Unread 08-10-2004, 08:35 AM   #1
Matthew T
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Join Date: Aug 2004
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More Sheet Vinyl Removal and Slab Floor Prep Issues

We are in the demolition phase of removing sheet vinyl and replacing it with large ceramic tiles.

Before starting the demolition, I read the archieved Advice Forum regarding installing “Ceramic over sheet vinyl ?”.

We tore up the sheet vinyl this weekend and opened a can of worms.

As the sheet vinyl came up, so did large chunks of skim coat or leveling product. The builder tried to level the floor on several occasions because the products vary in color from red to gray. In some cases, it was close to ½” thick. In other areas the felt backing stuck to the slab or has stuck to what is left of the skim coat. Underneath the removed skim coat, we discovered cracks in the slab. They could be described as the “hairline” variety (1/16” or less), but they are cracks nonetheless.

In sum, the floor surface is a mixture of surface textures and heights. Where the skim coat came up we have large depressions, but “clean” concrete. Where the skim coat is thinner it appears to have adhered to the slab securely, but we are unsure because it is covered with felt paper. In other areas the felt paper covers a mixture of floor leveling products. We tried soaking the paper with water and scraping it up, but that reactivated the underlying leveling product. When we tried scraping it up, we were removing as much of the leveling product as we were the felt paper causing more “unevenness” in the floor.

I’ve also read the archieved string regarding “Slab floor prep, after vinyl removal”, but I still have a few questions.

1. What products, if any, should be used to span the cracks to avoid transference to the tiles ?
2. Should those products be applied to the cracks before I use a leveling product ?
3. To build up the depressions in the slab I plan on using a self leveling product, but can those products be used in areas where felt paper remains ? The pervious forum on slab floor prep indicated that modern thin sets can adhere to felt paper, but what about self leveling products ?
4. Prior to using leveling products does some type of bonding agent need to be applied to the exposed slab ?
5. Based on all the variables (textures, heights etc.) with the floor surface, should I rent a floor grinder and start from the bottom up ?

I not giving up, but a floating floor system laid on top of the old sheet vinyl sounds really appealing right now. I just wondering what my next step should be ?
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Unread 08-10-2004, 08:41 AM   #2
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You need to get down to base concrete before you do anything else. The floor grinder's probably a good idea. The vinyl leveler has gotta come out. Once you got the concrete exposed, we can decide on the next step.
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Unread 08-23-2004, 06:37 PM   #3
Matthew T
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Alright, after the hurricane blew through Orlando I got back to our project.

We used a waterless grinder and removed all the old floor leveling compound and felt paper backing that was stuck to it.

Now we have to deal with the cracks and the depressions. The cracks are about 1/8" but run 10' and 25' long.

I looked at two products at the local HD. The first was Redgard. The guy at HD recommended it over the second product which was a crack protection kit from AFM. It involved using a patch that spanned the crack.

What products have worked best for you ?

After the cracks are patched what products do you suggest using to refill the depressions ?
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Unread 08-24-2004, 05:47 AM   #4
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Redgard is a better waterproofer than it is a antifracture membrane. Go with the membrane kit.

How deep are the depressions/dips?
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Unread 08-24-2004, 10:22 AM   #5
Matthew T
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The biggest depressions are 1/4" to 3/8" over about a 4' span.
You can feel them when you walk the surface.

As a related issue. I plan on using a variety of tile sizes the largest being 18" x 18". Is there a rule of thumb that I need follow for tolerances of the floor surface ?
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Unread 08-24-2004, 06:55 PM   #6
John Bridge
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Hi Matt, Welcome aboard.

You did not open a can of worms. You did what you needed to do to get a screwed up floor prepared for a tile installation. Your floor would have failed in short order had you installed the tiles over the vinyl.

Since you have so many cracks, and because they seem to be quite wide and long, I would recommend using a membrane over the entire area to be tiled. I know it's expensive, but that's what I would do. Use the self-leveling cement first -- get everything smoothed out -- and then install the membrane on top. Finally, the tile. Use the primer that is recommended by the manufacturer of the SLC.

I'm a Schluter man, so I recommend Schluter Ditra as the membrane. But a friend of mine who happens to be a high mucky muck at the Noble Company hangs around here too. His name is Eric, and he'll recommend his product, Nobleseal, which is also good.


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Unread 08-24-2004, 07:27 PM   #7
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followin' John

Evenin' Matt,

It's pretty tough to follow one of John's posts with anything really insightful but from thirty years of designing concrete stuff in chemical plants I will agree that you want to get down to good bare concrete. !/8" cracks are pretty good size but could probably be handled with a 12" wide strip membrane like Protecto Wrap, but this does create a bit of a bump to tile over. Using a membrane over the whole area after a leveling compound will give you what 18" tiles will unforgivingly scream for, flatness. I thought my floors were real flat until I layed several 18"sq tiles down and watched them rock or lip-up. This was not noticable with 12"sq tiles. As far as the added expense, picture youself months down the road, with many many many hours invested, looking at cracks in the tile or grout or both and thinking maybe if I'da just gone ahead and......

Good luck,

Mike Moran

"If it ain't broke......
You don't have grandkids"

major life achievments-
"accidently epoxied a cat to the garage floor"
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