Use plywood behind tile backer board?

[jonhamil]

So I'm about to box in some pipes and tile over them - I understand that tiling directly onto ply is bad obvs - just wondered if it's advisable to box in with ply and then overboard with tile backer board or do most tilers just go with board directly?

 

[Steve6690]

Jackoboard, Schluter and others actually make a pipe boxing board assembly, or you could get some board and knock up your own.

XPS pipe cover