Travertine Best Practice Wall Prep?

Hello,

I've been trying to find a basic guide to installing travertine tiles in a bathroom- without much success in finding something covering wall prep through to tile finishing.

I understand the following to be recommended for installing:

1) Use white/neutral adhesive/grout to avoid staining tiles
2) Butter the whole back of the tile to avoid discolouration spots from adhesive
3) Seal before and after grouting- several times, and every year.

What I'm not clear on is the wall preparation....do I need to tank the walls before putting tiles or or not? They are going on a shower wall which has good condition finishing plaster under the current tiles that are going to be removed. This is on the first floor of my house, one wall internal, one external on the other side to the bathroom.

I'm guessing I do, but trying to think it through logically, if a small amount of moisture does get through the tile or the grout, is it really a good thing to be trapping it between the tile and the wall?

If I do need tanking, then is it just a case of applying a liquid system such as BAL WP1 and using tape in the corners?

Many thanks in advance for your replies,

Pablo

My experience with travertine is they can be very heavy tiles.
Will your plastered walls hold the weight?
If its skim plaster probably not.

Personally I would use cement board like hardibacker and mechanically fix with screws.
Also I would use Bal cement based adhesive and grout.

I'm not a tiler.

Andy.