The angle at which pipes must fall The longest distance for lateral pipes And on and on and on through hundreds of pages When plumbers follow all the rules, they are able to create extremely reliable and safe plumbing systems. Over time new rules get added as people realize funny little quirks and nuances. These new rules prevent problems in the future, and each one makes the code a little bigger and better. This is all a nice way to say that, even though plumbing looks simple in this section, there are many subtleties and nuances dictated by code that plumbers know and neophytes generally do not. The same holds true for electrical systems, by the way.
Rough plumbing involves installing all of the water lines, sewer lines and the bathtubs.
A full tub is heavy. Therefore the tub is installed and filled so that the frame can settle quickly. This step prevents cracked walls and tile the first time someone uses the tub. Typically rough plumbing involves installing all sewer lines and vents as well as all water supply lines for each fixture. The tub is put in place and filled.