I understand that the layers under bathroom tile go (from bottom to
top):

Kerdi membrane
Chicken wire
Hardboard
Tile
What is the purpose of the chicken wire?

Chicken wire is used as a reinforcement in a custom mud bed shower pan.
Expanded metal lath, or metal hardware cloth would be better choices if
you can get them.

If you're just tiling a bathroom floor, you can skip the Kerdi and
chicken wire. Just install the backerboard, then tile directly over that.

If you're building a custom shower pan with a mud bed, you would normally
install a layer of roofing felt or rosin paper on the subfloor. This acts
as an isolation membrane, and prevents the subfloor from sucking the
moisture out of the mortar before it cures.

Then you would install your reinforcing wire, and build up your mud bed.
Hardibacker board is used on the walls.

Then you can install your Kerdi waterproofing membrane on the shower pan
and up the walls.

Finally, you can install your tile, and grout it once the thinset has
cured.

Of course, this is just a basic overview. There are a lot of details you
should research first. I recommend you visit the John Bridge tile forum
and study Kerdi shower pan installations:

http://www.johnbridge.com/vbulletin/

You can also see how I handled the different situations in our two
bathrooms at:

http://www.johnbridge.com/vbulletin/...ad.php?t=12876

Take care,

Anthony Watson
www.watsondiy.com
www.mountainsoftware.com