Feeling lucky to have found such a good forum and library of tips. I have a couple of questions that I have not found answered here...

I am in the demo stage of re-tiling a typical late 60s bathroom on second floor. I am looking for advice on what types of underlayment are suggested for replacement. Tiles have been removed from the tub/shower surround to reveal a 1/2 inch thick mud bed over metal lath. This surface appears to be in good shape and plumb. I have considered waterproofing and just tiling over the old mud. New tile will be standard 3X6 inch subway ceramic. Although, I might need to remove the wet wall covering to inspect and upgrade the older fixtures. Should I proceed with gutting the entire surround and start over, if there are no visible cracks in the existing mud job (to be safe)? What is the best practice for installing new tub surround underlayment? Can you point me to another post, if this is covered elsewhere?

The thick mud job on the floor was cracked in multiple places (no wire lath and a bunch of tile and trash in the mix), which had propogated thru the original tile. I have removed the substrate down to solid 1/2 inch plywood and have 2.75 inches to build up before new finished marble mosaic floor. Gotta love the 3 pound sledge! Assuming everything is level, what is the best way to build up the floor with plywood and CBU (and maybe isolation membrane)? I need to get pretty close to this build up on underlayment, as the tub is now substantially raised above the subfloor. the tub sits on a built up wood platform. I am hoping to avoid a new mud job unless there's an area I have not yet found that is significantly out of level.

Also, there was a 4-foot high tile waiscotting around the entire room. Outside of the shower surround, I want to replace this with a wood wainscotting on the walls. Any tips on demoing the mud and wire lath from the walls here and, if necessary, around the tub?

Thank you in advance for any help and guidance,
Berkley

I've been thinking about how I might best increase the underlayment stack on the floor. The plywood box the tub sits on is 2.25 inches from the existing plywood subfloor and sets my minimum underlyament build up height. I plan to keep the existing cast iron tub, which is in good shape. What about adding two layers of 3/4 inch plywood, guled and screwed to the existing subfloor. Top that with 1/2 inch CBU set in thinset. That would give me two total inches of underlayment with a quarter inch in gule and mastic. Any thoughts?

Thanks much,
Berkley