ceramic tiles on suspened timber floor

[skelton]

if laying ceramic tiles on suspended tiber floor, what type of ply and thickness

[weeal]

I found this on another forum:

Strengthen the floor by screwing down 1/2" flooring
grade plywood at 6" centres (12mm./150mm. in meteoric) Prime the floor with an appropriate bonding agent. Tile. You may also find you need to shorten the doors.

[The Builder]

......... also, best to use "flexible" latex adhesive............

[Clanad]

And.. for a truly long lasting tile job one should lay at least 1/2 inch thick cement board over the plywood... 3/4 inch would be even better.
The cement board,at least here in the U.S. is sold under a couple of brand names... I've used "Backerboard" on several applications. It's a little difficult to cut and fit since it is actually cement bonded to a covering material. One needs a special circular saw and jig-saw blade and even drill bits along with special zinc-coated screws. Having said that, it added only about 10% additional cost and maybe 5 or 6 hours extra labor time, but well worth it for a truly professional installation guaranteed not to de-bond and crack your tiles... We're in the U.S., but there's some good information that's universal in this site:

http://www.tileusa.com/

Good luck!