Flooring Tile - Very Small uneven area

I have a very small guest bath room that I am putting travertine tile on. I ripped up all of the old linoleum and scrapped up 95 percent of the glue used to hold the lino. I removed the old vanity and found a patch job that the builder left about a 4 inch crevice. I filled this with a concrete patch kit used to fill large cracks. Now I have painte on REDGARD to just be safe. There was one very small hairline crack, other than that the concrete floor was pretty level. Except on very small area that when I lay the travertine for the dry run the travertine wobbles. The other areas of the floor are very level. Question, do I need to put down a some backerboard over the whole floor to level that one very small area? Use self leveler compund over the whole floor for that small area? Or can I use extra thinset to compensate for the wobble?

Thanks for your time,

Mark Beard

Are you saying you used redgard over the entire floor or just the area you patched? Its a good idea to use a crack isolation membrane like ditra over any concrete floor. It will help protect your travertine installation against any future minor horizontal cracking on the floor and the small horizontal crack you already have from telegraphing though to the tile. If the travertine is 12" x 12" or bigger you may want to use a medium bed mortar. It will be easier to get all the tiles on plane, and make up that minimal rocking over the small hump. Do not put cement board over a slab. It sounds like you are talking about a very minor "rocking", so the thinset or medium bed mortar should be able to compensate for this.

HJ

I used the redgard over the entire floor. However, I didn't notice the little uneven area until I dry laid the pattern. I just finished, I grinded the area a little and just tried to compensate with extra thinset. I appreciate your time and your response very much.