Re: Porcelain tile in bathroom (underlayment question)

Ok, so I think we're ready to go this weekend. I've picked out my tile
and the grout is on order! A few questions before I get started.
First, cement backer board. I haven't stripped out the old tile/
flooring yet so I'm not sure what I'll find, but assuming everything
is "average" what size should I use for backer board? Is 1/4"
sufficient or should I be using 1/2"? The cost difference is
negligible so that's not the issue here. I'm wondering about height
difference in the new floor. Also, while I've read quite a bit about
the installation and I think I have the basics down, there are some
"technical details" that most how to books/sites don't really touch
on...

- screws for the underlayment - what type of screws should I be using
and how many? I read somewhere that using thinset under the backer
board isn't really to secure it to the floor, but rather fill in any
slight irregularities in the subfloor. Thus, I would need adequate
numbers of screws to firmly secure it to the subfloor? Do the screw
head need to be covered with an additional layer of thinset (i.e.
cover them like you would on drywall and then apply thinset for laying
the tile)?

- fiberglass tape on the joints - is this the same "adhesive backed"
fiberglass tape they sell for drywall applications? I usually use
paper rolls for this, but I know I have a few rolls of the fiberglass
kicking around.

I'm sure there will be additional questions, but this is what is on my
mind right now. I'm pretty excited to tackle this project and very
excited to see the outcome. Thanks for all your help thus far.

Kevin

Floor must be rigid or the tiles and grout may crack as it flexes slightly
when walked on. It's typically necessary to stiffen floors with a additional
layers of plywood and propretary board such as Hardibacker board depending
on what it's like. Use a flexible adhesive and the right kind of spreader as
well.

I'm in the planning stages of redoing the bathroom, the major project
to be putting porcelain tile on the floor. The existing floor is vinyl
tile - you know those industrial looking things you find in every
supermarket, convenience store and school!). The tile was there at
move-in 6 years ago, although I don't know if they are original to the
house (1970's). I am assuming that once I remove the tiles, I will
find hard glue and some sort of plywood - 1/4 luan paneling maybe?!
Assuming that this is in good shape (not rotting), will this be a
suitable base for laying the tile, or will it be absolutely necessary
to remove it as well and replace with cement backer board??