Is it possible? I have not seen much written on this, but I would really like to do it. I just don't understand why it would be a problem with an under-mount considering all the waterproof membrane stuff they have out. If I used this on walls coming down and onto the lip of tub, and put a slight 1/8" pitch into tub. I am only looking to have 6" of tile around the tub horizontally.

Sure you can. I don't know if I would use the word undermount but there's nothing wrong with having a horizontal area around a tub that also has a shower. You don't even have to slant the 6" in towards the tub.

If you are concerned about resale: seems the entire US wants a separate tub and separate shower these days.

Hi Mikect05...

Basically, there are 3 types of tubs: 1. Self-Rimming, 2. Tile-To and 3.Tile-Over. You are asking about the Tile-Over tub.

Tile-Over tub installs directly on to wood framing (pedestal). Backing board ( or light concrete ) is than installed on flat areas surrounding tub and finished with tile ( or stone ) overlapping edge of the tub.

It is a common way of installing tubs. However, with Tile-Over tubs, people usually don't use shower heads mounted high on the wall. Shower is usually mounted on side of the tub or on the flat, horizontal surface around the tub.

Now if you want to install shower high on the wall than you have to deal with it as with regular shower: you have to water proof vertical and horizontal areas around the tub. In my area of operation we prefer to use hot mop method of waterproofing but some installers prefer to use PVC liners with same results.

As you already mentioned - slope all horizontal pieces at at least 1/8" per foot towards the tub. Test the slope for proper run-off. If capillary action occurs than add to the slope.

Hope that helps... Milo