Framing a new closet door

[millinghill]

Hi, I'm framing a closet in my basement. The pre-hung door I bought says it needs 81.75" height for rough framing and I need to set the framing across the top of the door (the "header", I guess). Floor is currently concrete and I've yet to install:

1. Tile Membrane (i.e. Schluter Ditra) and any required adhesive for this
2. thinset mortar.
3. ceramic tile.

What's a reasonable thickness to assume for these three so that I can set the door header?

Many thanks Theodore

[Ed Pawlowski]

Id allow: thickness of known material + 1/4" for adhesive + 1/4" just in case. Gap at the base of a closet door is not a big deal and easier than having to trim the door later.