Hey, I'm looking for advice.

I'm in SLC helping a friend with her bathroom. We are removing floor tile and will replace it with new tile. I'm using a RotoZip with a blade attachment to cut the tile, then I tap it and remove it. It comes out fairly easily with this method. Underneath the tile is about a 1" concrete(?) subfloor. I have been scoring the subfloor when I cut the tile. Here are my questions:
1. Can I use the tile's thinset to fil those score lines?
2. If not, can I use floor leveler?
3. If not, do I have to take out the whole subfloor?

She wants to remove the subfloor. I really don't think it's necessary. It's going to be VERY time consuming, and we'll need to match the thickness of the old subfloor so that doors, cabinets, tub, etc... line up.

Gimme your advice, I'll appreciate it no matter which direction it makes us go.

Thanks!

Ok,
so you cut into the sub floor which is a poured concrete?
The first layer of floor is the sub floor.
the upper layer is underlayment, we will talk about the underlayment, or the poured concrete underlayment.

How thick is it?
How far did you cut.
What type of tile will you be using?
What type of mastic will you be using?

Now I will try to answer based upon some assumptions, but I think you should also run this by Trekkor. Go hnt him down on the other board, he does tile for a living.

If you use the correct type of mastic to set the tiles, it will be grey and look like mortar, but have the consistency of mayo that was left out...so just on the edge of soupy.
I would take a small amount of that out of the container, and dump it into another container, like a paint bucket.
Now add some water, or the "moose milk" additive that comes with it to make it a consistency of a milk shake, or a frap.

Make sure the floor is all clean, no bumps, and old adhesive, and cover the whole floor with it, but only paper thin.
Push hard with a flat masory trowel to fill all the cuts, and crack you made. Make sure you go over those several times, and lean hard on the trowel to squeeze it in the crack.

You can tell her this.
The mastic will stick to pretty much anything.
Its waterproof, and is masonry based, so it works great with the mortar underlayment.
The original mortar underlayment was just a dry mixture of the adhesive that was used to lay the tiles, at least it typically is.

It is how you do it.

If you broke a section of the floor, you need to get masonry mortar, or there is probably some special stuff in the tile isle at HD.
Its a simple mortar, mixed pretty dry, and again, trowel with lots of weight to pack it down and get all the air out.

Now, let it all dry.
Next day, you can lay floor.
If you just need to put on the skim coat to fill small cracks, by the time you clean up the mess from putting the skim coat down, you can lay tile with the thicker mastic.

In the future, rent a small hammer drill with the chisel attachments, or use an air chisel, it takes alot less time.
When removing tile, WHEN the underlayment gets damaged, just fill it in and keep going, provided it has not lost its grip to the subfloor

Rich

Fixall or quikrete patch should do the job, neather of them shrink while drying. Fill the

scores and let dry, make sure your repairs are flush with the rest of the floor.

Set the tile.