Bead board - Above or Behind Tile Baseboard
 

We want to install cellular wood bead board planking in our bathroom. We also plan on using excess tile for a tile baseboard. Should the bead board be placed on the tile baseboard or should the tile baseboard cover the bead board?

The tile wants to be on something really stable. I would start with something like a 1x4 on the wall and tile to that and put the beadboard above that with a little cap molding of some kind.

I have had good results using tile for thebase board in bathroooms. However, they were set over a tile floor that had a concrete foundation and the walls were good and sound (no water damage/rot in bottom plate).
If you do put tile on the wall with a differant type of floor I would use a laytex modifier in the thinset and use a thin spacer to hold the tile off the floor while you set and grout. Then finish the small gap to the floor with some of that flexible grout in a tube for a calking gun.

your not going to want to put the tile on the beadboard, to many little grooves to deal with and beadboard is not stable enough. I would go with Nealtw's idea.