Basement Bathroom

[John28]

I'm now wanting to remove the old mosiac style tile from my basement bathroom floor and install larger tiles 6x6 or 8x8?

When I removed some of this tile, it was like a mastic of some sort? It would flake off in a plastic type consistency tan in color, where to totally remove, you'd have to grind it off, as little chunks stick just chiseling the tile off.

The subfloor is concrete, but the old tile adhesive is not a thinset, which is my concern, as the floor has some slight dips, that didn't effect the old mosiac tile, but not flat enough for larger tile.

As to use a leveler, I realize I'd have to grind all the old adhesive off for proper bond, for a true flat floor, but really hate to grind all this.

So my questions 1. Would thinset like Versabond stick to this surface considering the majority of the old adhesive would be chipped off, but with some remaining specks through out the surface?

2. Being the floor is not super flat, although not really that bad, considering if I could use thinset? Could I just knock the few high spots down, and overfill the low spots with thinset to get flat? I realize a thinset shouldn't be buit up that much, but it wouldn't take much extra then setting tiles if I knock the high spots down first. Just trying to avoid the mess of grinding, thanks

[cx]

1. A few specs won't hurt, but you gotta mechanically remove nearly all that old adhesive down to clean concrete.

2. We have no way of knowing what you might mean by "[b]eing the floor is not super flat, although not really that bad...," John. The industry requirement for flatness for the size tiles you plan to use is no deviation from intended plane of more than 1/4" in ten feet nor 1/16th" in any one foot. If your floor doesn't meet that flatness requirement, I recommend you correct it before tiling.

Grinding the high spots and filling the low spots is generally the way that's done. Thinset mortar is not an appropriate material for the flattening process, though. Every manufacturer of tile bonding mortars also makes patching and leveling products for your application.

My opinion; worth price charged.

[John28]

Thanks

1. Yes I can manually chisel the majority off, but reqiures a lot of chiseling, actually grazing the surface and scoring with the chisel over and over. But willing to put the extra work in vs. the messy grinding of the entire surface. Afterwards the specs are very minimal, but just wanted to check.

2. As for flatness, the overall surface is flat, but has some finishing dips, 1/4 max. Who ever finished it created a few trowel dips, and pushed this surface to create high spots next to the dips. Looking with a straight edge, knocking the few mounds down, the dips might then be very minimal. I'll go that route and use a patcher if needed. Realizing thinset is not for patching, but if the low spots end up minimal 1/16 or less, after knocking the high spots down, would it be accepatble to go a bit heavier in these spots with the thinset while setting to make a flat tile surface? thanks

[Davy]

I would want as much of that mastic removed. Some times just hitting it with a hammer will bust it off. I would look into getting a chipping hammer, Home Depot rents them. One of these would probably work.

[John28]

Thanks, I'll look into a chipping hammer, never saw one before.

[cx]

Originally Posted by John

...the overall surface is flat, but has some finishing dips, 1/4 max.

Now, John, you gotta come to grips with this. Your surface is either flat or it's not, eh?

See #2 in post #2. You have that?

[John28]

Yes, I'll have to check it better per #2, once all the mastic is off. As there are big globs in areas, that might have contributed to the high spots?

[John28]

As previously posted, what is the exact name of this chipping device? Searched the web for one and could not locate, need a more specific name.

This one looks like a set for a chipping hammer, and wonder if they also have manual ones just to hit with a hammer?, as it's not a very big bathroom, Thanks

[Houston Remodeler]

Yes John, they make manual ones but you'll wish you never used it. Rent a chipping hammer. They are waaaayyyyy cool.

[John28]

Yes, but do you know what that set is called? I'm guessing a concrete tenderizer?

[Houston Remodeler]

Its called a bushing tool.

I don't know why

[cx]

I, too, have no eye-dee why it's called a bushing tool, John, and I, and at least one other contractor known to me, have always called it the meat tenderizer. Tell your helper to fetch that and you'll always get the right tool.

[John28]

Bushing Tool? And a very expensive bushing tool, atleast the better carbide tipped ones? I agree, tenderizer would have been a better name for it, doesn't look like the bushing tools I'm familair with?

[cx]

I've never owned a carbide tipped version, John, and hope never to use one enough to justify buying one. The regular non-carbide ones will pulverize a whole gaggle of concrete surface.