Ceramic tile question

[Daniel]

I'm finishing off a new bathroom in the basement, and am at the point where the ceramic tile flooring needs to go down.

I'm getting mixed answers to questions re whether to use floor leveler. My basement floor is level but uneven; in other words, it's not a smooth surface, is pock-marked and "grainy." It was also painted at one time, but most of the paint has worn off.

I'm inclined to put the floor leveler down to eliminate concerns about applying the tile to a level floor; however, I've had one "knowledgable" person tell me I'd have to etch the floor first or the leveler won't stick.

I've had a couple other people tell me the best foundation for ceramic tile IS concrete, and that the pock-marks won't be a problem if I just go ahead and fill them in with mortar.

So, at this point I'm wondering if there's any advantage at all in putting down the leveler. I want the job done right, but I must say my attitude goes south at the prospect of etching the concrete before I proceed.

Anyone put ceramic tile on a "rough" concrete floor? What were the results? Suggestions?

Thanks.

[Ed]

From National Floor Trends Magazine: "Prepping Concrete Slabs for Ceramic Tile Installation"

[Noozer]

If the concrete is level I'd just make sure that the paint was completely removed and coat the concrete with a bonding agent. Put tiles onto the concrete. The rough concrete with bonding agent will hold well.

[Robert Allison]

Will the tiles lay flat on the floor the way it is now? If they lay flat and don't have more than a quarter sized pock mark or nothing more than a 1/4" or less in depth, then forget the floor leveler. The floor leveler is to correct problem substrates that would give you a wavy floor or to fill depressions that could cause a void. I don't know what the standard for voids is, but I don't like voids that are larger than a fourth of the tile width. I don't even like them, but I just fill them with thinset.

A slight depression can be corrected by the way you lay the tile. If you use the correct notched trowel, it will give you a lot of room to wiggle. Be careful in the laying of the tiles and you will be fine.

[DaddyMonkey]

I would be more concerned about the paint on the floor than I would a rough, pockmarked surface.

A rough surface will give the thin-set mortar a little something to 'bite' into and actually give better holding than a concrete floor that's as smooth as glass.

Good luck, Dave

[SQLit]

I always etch with muratic acid and a lot of ventilation. Neutralize with baking soda in water and vacuum up the residue using a wet vac. Then using a roto hammer I purposely rough the floor area. Let dry then using thin-set and a notched trowel that will cover up the low spots not exceeding 1/2 of a inch: lay the tile. The thin set will bond to the etched concrete well as long as the paint is removed. If you use 1/2" of thin set, it could take a week or more depending on the temp and humidity. Using the thin set as a bed is a established method of leveling the finished floor tile.