master 1/2 bath remodel

[ssim1s]

First time user to forums, so bear with me my learning curve is short.
First of all my wife decided we needed to redo the master half bath and as I know from many other remodels the cost can get out of hand if not properly organized.
Our 1/2 bath walls were already tiled with a baby blue 1962 4" tile that if we waited maybe 5 more years it would be back in style, but new granite on the floors and countertop and ceramic tile on the walls will better occupy my time during my next layoff.
First big question - rather than tearing down the sheetrock walls and starting with new greenboard or hardi board I was wondering what your thoughts were (since there is no shower or bath) to just applying kerdi over the walls and going for it. (As you can put 2&2 together I would like do as best of a job possible with the least added exspense).

[Rd Tile]

Are you asking if you can go over the old tile?

No shower or bath?, why Kerdi, I would rip it all out, install new drywall and go from there.

[cx]

Welcome, ssim1s. Please put a first name in a permanent signature line for us to use.

What Richie said.

I see no application at all for Kerdi.

I suppose a fella could tile over what he has if he can figger out a nice looking way to terminate it all.

I'd be inclined to tear out all the tile walls, sheetrock again, and start over.

My opinion; worth price charged.