PaPaPeng wrote:

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?

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 he

http://tinyurl.com/2nd7fa

--
Robert Allison
Rimshot, Inc.
Georgetown, TX