I am planning to tile a backsplash over drywall from which older tile will be removed. In another area, the outer paper is almost entirely gone.

What do I need to do to prep the drywall for the new tile? So far I've only started with new, intact surfaces. Any advice will be appreciated.

If possible I would cut the damages drywall out, replace with new drywall, rough tape and mud the seams and then tile over it.

I was afraid of that. I'm not sure how possible it is because I'm working around cabinets and other things that are already in place. The old tile goes right up to the cabinets. Im replacing the countertops, so that helps. I'll have to do study it and see what is possible without causing even bigger problems.

Can you post a couple pics of the area to be worked?

I re did our backsplash and had to replace damaged drywall from pulling out the countertops and old backsplash. In a couple areas it went right up to the bottom of the cabinet (about a 1/4 inch below) I'm not sure if it was kosher, but I just didn't tape and mud that area. I got as tight a fit as I could, put a little spackle in the seam and then tiled over it. Came out fine

Outer paper, I'd probably use 1/4" hardibacker. Chunks gone, I'd look into replacing it in areas.

As the Fife, Hardie backer and move on.

I wouldn't worry about the paper being gone but if you're going to tile over drywall, I'd strongly recommend using a waterproof backing.

Sully- please post some pictures so we can see how big of an area is damaged and how bad the pitting is. You're getting advice from folks who haven't seen the problem. Depending on size and severity, you may be able to repair satisfactorily without replacing. Please also confirm whether this is a kitchen or bath backslash.

Thanks everyone. I got tied up yesterday and almost forgot about this thread. I'll see if I can get pictures and post them this evening. This is a kitchen backsplash.

When I posted, I hadn't removed the old tile yet. Now I have and the damage isn't as bad as I feared, but there is definitely some. There is a small place where I got too aggressive with my bar and put a hole in it, but otherwise the damage isn't too bad. However, there are places where the paper is torn, other places with residual mastick and the old tile goes over a horizontal seam in the drywall and there are places where the old mud tore out. So, its all pretty rough.

The other issue is the area behind the stove, where a previous owner had glued laminate to the drywall. Removing that completely, tore off the outer paper layer of the drywall. Also, the old counter top is a standard premade laminate with the built in 4-5 inch backsplash, and that was glued to the wall as well, so removing it removed the paper as well.

I like the idea of the hardi board. If I smooth the existing wall as much as possible and then put up 1/4 inch hardi board would that solve my problems?

If it's just the paper you should be okay with perhaps floating those areas. Once chunks of drywall start coming out then it needs to be replaced.

Hardi isn't necessary for kitchen backsplashes and would be overkill. Installing 1/4" Hardi over the damaged sheetrock might work, you would need to use a tile selection that had a bullnose version or install small tile returns or a wood trim to cover the edge. I'd just patch the damaged sections instead.

Just float it out for an even surface and get busy