As will be seen later, in the description of the Durham plumbing system, whenever wrought-iron pipe is used for drainage purposes, the fittings used in connection with it should be of cast iron. They should be of the style known as extra heavy cast iron, recessed, and threaded drainage fittings. These fittings should also be used on main vent lines of wrought iron, although it is true that in many cases they are not used on such work. For fixture and branch vents of wrought iron it is permissible to use galvanized cast or malleable steam and water fittings. In the use of short nipples on either drainage or vent work, special care should be taken in order that they may not be split or crushed in any way. When the nipple is of such length that the distance between the two threaded ends, that is, the part unthreaded, is less than 1 inches, the nipple should be of "extra strong" pipe. The term "roughing-in" is applied to the plumbing system when it has reached the point where the first test is to be applied. The "roughing-in" includes the entire soil-pipe system, house drain, soil and waste stacks, main vent lines, all branch wastes and vents. In fact, the "roughing-in" includes the entire plumbing system with the exception of exposed work above the floor, that is, the fixture itself, its trap and waste to the floor, and the vent connection to the wall. Figs. 89 and 110 will give an idea of what is meant by "roughing-in." In roughing-in, wherever waste pipes are to be run of more than six feet in length, lead pipe should not be used. The use of lead for drainage and vent work is fast going out of date, cast and wrought iron and brass taking its place. The labor involved in lead work, properly constructed, is greater than in the use of other materials; it is less rigid; long lines of lead pipe are liable to sag and form traps; and lead pipe is sometimes subject to the attack of rats, the generally accepted idea being that in their attack they are attempting to reach the water which they hear flowing through the pipes. To such an extent has lead work been replaced in many parts of the country that the trade of the plumber of to-day has changed almost entirely from that which the old-time lead worker followed. There was a time not many years back when the plumber made his own traps, bends, etc., and a time when lead soil pipe was used. All that is now changed, and although the older plumbers may not agree to it, it would seem that this great change is for the better. In the running of horizontal soil, waste, and vent pipes, they should have a grade of at least one-quarter inch to the foot, and more than this amount is preferable. Wherever possible, each fixture should have a separate entrance into its stack. This is a practice which is by no means generally followed, and it certainly does not receive the attention which it deserves. Referring to Fig. 90, it will be noted that the bath tub and lavatory are served by the same line of lead waste pipe. This is not to be considered an unsanitary practice, and many times it would be almost impossible to construct the work otherwise. If the waste pipe should become stopped at any point between the lavatory connection and the stack, it may readily be seen that both lavatory and bath would be affected. If each had a separate connection the stoppage of one waste would not affect the other. It may be stated further that very often the plumber might obtain separate entrance for each fixture, but in a vast majority of cases the work is taken under contract, and the betterment of the work by making separate entrance would result in additional expense to him. In other instances the architect might easily lay out the work and make locations of pipes and fixtures such that separate entrances might easily be made. For instance, in the floor plan of Fig. 91, the relative locations of fixtures and stack are such that each fixture may waste independently into the stack, as will be seen in Fig. |