Kerdi over Blueboard or Plaster?

[preppucci]

My plasterer got carried away and blue-boarded and plastered the shower stall I'm doing instead of leaving it alone so I can board it with gypsum board or cement board. Has anyone ever used Kerdi over Blueboard and Plaster? I know the manual does not list this as a recommended substrate but I'm wondering if I can go over it with the Kerdi Band and sheets? Plaster is definitely a harder, more waterproof surface than gypsum board, which is a recommended substrate. I also have a section that is just Blue-board....can I use Kerdi Band over this?

I would hate to rip it out and replace with gypsum, but I will if I have to. Thanks in advance.

[scuttlebuttrp]

I would call Schluter and check with them.
By Blueboard do you mean Densarmor? or is this some fancy plaster stuff.

[preppucci]

Hmm, Blue-board to me is blueboard. It is gypsum covered with a blue paper...I guess makes the plaster adhere to it better. Here in the Northeast, typical wall finishes are either Blueboard with a thin coat of plaster over it......or drywall with taped seams and joint compound over the nails and seams. Plaster is a more durable, better finish and more water resistant than drywall.

[preppucci]

Just call technical support at Kerdi and the representative said I can go right over it with an unmodified thinset. Phew! Maybe since blueboard and plaster is cheaper and smoother than cement-board, I will do it this way from now on. That is if it comes out alright.