On Jun 3, 1:44*pm, CB wrote:
So we're redoing our bathroom and it's out to the studs.

snip

I have just hung kraft faced insulation, so my question is with
greenboard....do I use it in combination with the kraft faced
insulation (r13)? *Some out there say to not use greenboard if you've
already got kraft faced insulation up b/c then there's 2 vapor
barriers and the moisture could get trapped in between the layers.

Yes, greenboard is OK. It is a so-so vapor barrier, but its basic
important property is moisture resistance. Best used with setting type
compounds and fiberglass tapes for best water resistance.

Second question - greenboard on the ceiling or no? *Some say it sags.

Definite NO according to one customer service query years ago at a
major drywall maker. Maybe not as important with some of the newer
types of drywall (mold resistant, etc.) now on the market.

FWIW - the drywall I took down was 30 yr old normal gypsum board, and
the insulation behind it was in decent shape, although poorly
installed. *The painted walls appeared decent for a 30yr old bathroom,
although there was some moisture/drip lines from shower steam.

Likely your project will turn out quite well. Good luck.

Joe