The necessity of subflooring?

[PaPaPeng]

I have a 28 year old house. The linoleum need to be replaced in the bathrooms and the front door landing. I intend to use 13" x 13" ceramic tiles. A neighbor who had already done his recommends that I add a plywwod subfloor so that the base will be rigid. This is to prevent the tile cracking. I would prefer to glue the tiles directly to the existing floor. 1. to keep the floor thickness low, 2. skip a lot of extra work, 3. In 28 years the floor seems very stable and does not creak or "bounce."

Is a subfloor absolutely necessary? If so how does one fasten this subfloor to the existing floor - glue, nail or screws?

[Robert Allison]

Not knowing the age of your home, I will assume that it is of recent vintage. If so, then the floor is probably 3/4 inches thick. That is too thin for tile. Even though you may not notice any flexing, it does flex. And it will flex too much for tile.

You need to add the additional 1/2" both screwed and glued to the existing flooring for a total of 1-1/4". This should give your floor the stability it needs for tile.

If you don't, then the tiles or the grout or both will probably crack.

Look here:

[Steve Barker]

If you use your existing floor, just use a portland cement based tile adhesive. Not the cheap crap that comes in a tub. You'll have no cracking.

s

[Big_Jake]

If he has 24" OC floor framing, he can use the $50 / bag thin-set, and still have big issues.

JK