The house drain is that part of the horizontal soil piping of the drainage system which receives all soil, waste, and drainage pipes of the house. In Fig. 72 is shown a plan view of a house drain, with its various connections, which may be referred to in relation to some of the following considerations.
As previously stated, it connects with the house sewer at a point 5 to 10 feet outside the foundation walls. This provision is made in order that in the event of the breaking of the house sewer, which is generally of earthenware pipe, sewage may not be able to leech back through the foundation walls into the basement or cellar. The house drain should never be of earthenware pipe, the proper material for this work being either cast or wrought iron pipe. Wherever the house drain is run underground nothing but extra heavy cast-iron pipe should be used, wrought iron being especially susceptible to chemical action and decomposition when used underground. Special provision should be made in constructing the foundation wall, to allow a passage through for the house drain. This is a point, the importance of which seems to be but little appreciated. The settling of the foundation walls is liable to crush or crack the pipe at this point unless the danger is guarded against. Figs. 73 and 74 show the proper method of construction. The opening should be constructed with a capstone across the top, and with space on all sides of the pipe.
Fig. 73. - House Drain through Cellar Wall.
If the drainage system is to be provided with a main house trap it is best to place it as close to the point where the house drain passes through the foundation wall as possible. There is much to be said for and against the use of the main trap, the subject being of such importance that a special chapter will be devoted to its consideration. The house drain should have a grade of one half inch to the foot wherever possible, but in no case should it be less than one quarter inch. This provision applies to all soil and waste pipes also.
Fig. 74. - House Drain through Cellar Wall.
In running the house drain and, in fact, all other cellar or basement piping, it is always better practice to hang the piping from the timbers, exposed to view, than to run it underground. The running and supporting of soil piping thus installed may be seen in Fig. 75, the supporting of such lines being made by means of straps and hangers firmly secured to timbers, and by means of brick or stone piers resting securely on the cellar bottom.
This, of course, cannot always be done, especially if fixtures are located in the basement or cellar. Some cities require all underground drainage pipes to be inclosed in a boxing of chestnut planking. This requirement is a good one, but it may be said that it is followed in comparatively few cases. Into the house drain are connected not only the soil and waste stacks but also cellar drainage pipes, rain leaders, yard drains, etc., unless separate sewers are provided for surface and subsoil water, in which case the three last-named pipes would enter the surface-water house drain.
Fig. 75. - Running and Supporting of Exposed Cellar Piping.
In Fig. 76 is shown an illustration of the house drain, with the several lines of soil and drainage pipes entering it. All branches leading into the house drain should be made by means of Ys. Tees should never be used for this purpose, and T-Ys are objectionable on horizontal piping. The Y is preferable, for the reason that waste is carried into the house drain by means of it in a less abrupt manner, obviating to a large extent the splashing of the waste against the sides of the pipe opposite the entrance. The splashing naturally causes substances in the waste to collect about the entrance of the branch, which will result in impeding the flow not only in the branch but in the house drain as well. Wherever right-angle turns are made in the piping, whether it be on horizontal or vertical lines, the change in direction is made by means of a Y branch and one-eighth bend.
In Fig. 77 are shown several examples of the proper methods of making changes in direction in running soil pipe, and in Fig.
Fig. 76. - The House Drain and Pipes Discharging Into It.
78 are to be seen examples of similar work, in which changes in direction are improperly made. The reasons for considering the connections in Fig. 77 preferable to those in Fig. 78, are those which have been given above.
In Fig. 76 the connections of the waste and soil stacks into the house drain are examples of the methods of connection of Fig. 77. A cleanout should be used at the end of each horizontal run, as seen in Fig. 76.
The supporting of soil piping is a very important matter, one of those points, by the way, which is very liable to be overlooked, both by the plumber and by the architect. It is not an uncommon thing to see the house drain supported from the cellar timbers by rope and wire, or run on the face of the foundation walls with no other support than wooden pins driven into the crevices. Such methods are entirely wrong. Under each vertical line of soil or waste pipe, at the point where it enters the house drain, a firm foundation of brick or stone should be provided to sustain the weight, which in the case of high buildings is often very great. Vertical lines should be supported at each floor by means of wrought-iron bands placed under the pipe hubs, and securely screwed to the timbers. Another method of supporting vertical lines is shown in Fig. 79, from which it will be seen that the pipe is so cut that at each floor it rests upon a hub. Entire dependence for support should not be made upon this method, however.
Fig. 77. - Correct Methods of Making Changes in Direction in Soil Piping.
Fig. 78. - Wrong Methods of Making Changes in Direction in Soil Piping.