Tile over brick?
 

I have a brick hearth/bench and half-high wall with my fireplace in the middle. If the wall-long bench is flat enough, can I just set the flagstone tile over it w/o laying down a backer board first?

What about the face of the brick wall? Do I need to place a backer board there first? Thanks.

You can tile on brick but you need to skim coat it with thinset first ( like you would drywall ) then key it in with at least a 1/4 x 1/4 trowel. Use VersaBond Flex thinset, you can get it at Home Depot

:)

Yeah TileGuy is right, just cover it with the thinset mortar and it will hold on there. Here's some info on it:

http://www.floorstransformed.com/choosethinset.html