Re: Help with tiling in bathroom!!
Toilets are set on top of tile all the time. Where the problem comes in is that the toilets are not properly set or maintained, which then causes the leak. When setting a toilet on tile, the tile is flush with the flange (drain under the toilet ). It is imperative that both the flange and toilet base be as clean as possible so that the wax ring sticks and creates a good seal. I personally like the wax rings with the plastic flange insert, it just adds one more "anti-leak" measure to the equation. The toilet is then gently wiggled into place so that the wax ring is crushed evenly and the toilet sits firmly on the floor. Add nylon shims around the perimeter of the toilet if the tile is uneven enough to cause the toilet to wobble. The hold down nuts are then tightened just until snug, if they're over tightened you can break the base of the toilet. After one to two weeks, go back and check the hold down nuts again to make sure the toilet hasn't further settled into the wax ring and become loose. One of the reasons to fully tile under the toilet is that it seals the floor to the flange so that if any leak occurs, it will weep out from under the toilet and be seen (as long as it's not been caulked to the floor). It's also a cleaner, neater, more professional look than trying to notch and grout around the base of the toilet.
I've never seen tile go under a tub/shower, and IMHO it shouldn't because it will create height issues with drains and possibly support issues depending on the type of tile, installation method, and tile base (underlayment of the tile ). Another reason is that during construction, the tub/showers are usually installed during the plumbing rough-in and rough framing and flooring is one of the last items to be installed, so as a matter of timing, you'll be hard pressed to find finished flooring of any type under a tub/shower.
Whether you tile around or under a cabinet is personal preference, both methods have their merits. If you've got a pedestal sink, tile under the sink area first, then install the sink. The pedestal slides into place after the sink is set (attached to wall) and you'll need to be able to remove the pedestal for access to the sink drain and supply lines. Like the toilet, it will also be a cleaner, more professional look to have the pedestal on top of the tile, rather than the tile butted to it.
Hope this helps.
I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!