From the IRC. (bold and underlining are mine)
- SECTION P2705
- - INSTALLATION
- - - P2705.1 General.
The installation of fixtures shall conform to
the following:
- - - - 1. Floor-outlet or floor-mounted fixtures shall be secured
to the drainage connection and to the floor, where so
designed, by screws, bolts, washers, nuts and similar fasteners
of copper, brass or other corrosion-resistant
material.
- - - - 2. Wall-hung fixtures shall be rigidly supported so that
strain is not transmitted to the plumbing system.
- - - - 3. Where fixtures come in contact with walls and floors, the
contact area shall be water tight.
- - - - 4. Plumbing fixtures shall be usable.
- - - - 5. The centerline of water closets or bidets shall not be less
than 15 inches (381 mm) from adjacent walls or partitions
or not less than 15 inches (381 mm)from the centerline
of a bidet to the outermost rim of an adjacent water
closet. There shall be at least 21 inches (533 mm) clearance
in front of the water closet, bidet or lavatory to any
wall, fixture or door.
- - - - 6. The location of piping, fixtures or equipment shall not
interfere with the operation of windows or doors.
- - - - 7. In areas prone to flooding as established by Table
R301.2(1), plumbing fixtures shall be located or installed
in accordance with Section R323.1.5.
- - - - 8. Integral fixture-fitting mounting surfaces on manufactured
plumbing fixtures or plumbing fixtures constructed
on site, shall meet the design requirements of
ASME A112.19.2 or ASME A112.19.3.
Also note that, for those times when a door hits a toilet or lavatory, 6. above applies and prohibits that.