Flooring Tile - tiling a bathroom

I would like to install tile on our bathroom floor and tub walls. I have 3/4" plywood over 2x10 joists 16" o.c.. Floor joists are in good condition. The span of the joists is 14' but there is a support beam in the middle of the span and the bathroom is mostly on one side of the beam. I would like to know what else I need to do to the floor before I lay tile. Do I need to install additional plywood then a cement backerboard, or can I just proceed with the backer board. What thickness cement board should I use in either case. Also, what type of "adhesive" do you recommend for the floor and the walls. I have always heard of thinset, but the tile store recommended bonding mortar so I didn't know which to buy. Any help would be greatly appreciated.

The structure is more than sufficient.

Spread thinset over the plywood and screw down 1/2" cementboard, using a zillion screws. Do the seams with cementboard mesh tape and more thinset. Leave 1/8" gaps between sheets and between the cementboard and the walls.

For floors, you have no choice of adhesive. You must use thinset (and not the premixed stuff). Go to Home Depot and buy a bag of "Versabond".

In dry situations, you are allowed to use mastic as the adhesive for walls, but I'd strongly suggest using the same Versabond you used on the floor.

P.S. Versabond is a "bonding mortar". But it's also called thinset. So both you and the tile guy were correct.

Thank you John for your help, I will proceed as directed.

I should have been more clear for the tub walls, actually they will be shower walls, with a tub. My plans are to wrap the studs with 15# roofing felt, then 1/2" backerboard, then the tiles. This is how I was directed, is this the correct procedure. Thank you in advance for your assistance.

take the same mesh tape and tape the joints and corners in the shower as well,take a little thinset on the trowel and with the flat side skim ov er the tape and let dry:cool:

Well, its been a long time coming, (I had some other obligations to fulfill) but I have layed the tile on our bathroom floor, and I must say, for the first time I have done tile I think it went pretty well. Thank you for your help. What I am wondering is do I need to put anything between the toilet and the tile floor? It seem that to me that you shouldn't have such hard surfaces directly in contact with each other? Thank you for your help.

It's done different ways by different people, but I like to run a bead of silicone caulk around the bottom of the bowl before I set it on the floor. Let the caulk set up before using the toilet. This does two things good and two thing bad.

Good: (1) It cushions the bowl a little accommodating slight unevenness of the floor. (2) It keeps water spilled on the floor (e.g., from an overflow) from running under the toilet. This may bive you a couple of extra minutes to wipe it up before it ruins the ceiling below.

Bad: (1) If the toilet leaks at the wax seal, you won't get that wet spot on the floor to let you know. (2) When you replace the toilet, you'll need to slide a knife under there to cut the bowl free.

In my opinion, the good outweighs the bad.