My first post here and I need some advice.

I wish to tile the floor in our en-suite bathroom. The current floor is t+g floorboards, there is no movement in the floor joists (span between the two walls is about 900mm)
I originally thought of screwing hardboard down to even the floor out but was advised by my tile supplier not to use it but to use plywood instead.
I do not want to raise the floor much as there will be carpet in the bedroom and that would mean a small step into the en-suite.

Another question I have is do I tile the walls before the floor? or the other way around.

Thankyou,
Mark.

would use 6mm cement boards if your trying to keep the height down and there is little or no deflection,it doesn't really matter if you do the wall or floor first unless you are following the grout line from wall to floor then it's probably better to do the floor first,if not i would baton the room level 1 cut tile from the bottom,complete the walls do the floor then put the last cut in so you get it exact

Can I just screw the cement boards to the floor?
What about the joins, any special sealants for in between them?

Thanks again.

This should give you the information required http://www.jameshardie.co.uk/pdf/ins...eBacker250.pdf

use 9mm ply screwed every 200-250mm with 1 inch screws.use a flexible adhesive and grout on the floor.

As above. However, if you are using "No More Ply", they advise sticking down with their branded polyeurethane adhesive, as well as a bead between edges, then screw down.

I agree that 6mm cement boards are the way to go, but check install details with supplier / manufacturer.

As long as your T&G flooring is soild (NO movement) and you are concerned about the height - Go with the Hardie tile backer boards.
You fix them with the same fast set flexible adhesive as you fix the tiles and compliment it with 25mm screws in the positions detailed on the boards. The joints are taped and screeded again with the adhesive. The sheets come in sizes of 900x1500mm.
Always tend to tile the walls first but leave the bottom tile/cut off then do the floor and the cut/tile last. Check to see if you can bond the wall and floor tile joints.