Plumbing plans show only the quantity, extent and layout of the work, but give no indication as to the character of the goods to be used or the quality or make of the fixtures; consequently a description or specification must accompany the plans to make clear the requirements not shown or indicated. For instance, where water-closets are shown on plans, in the absence of an express description of what kind of closet is to be used, any fixture, from the cheapest hopper to the most expensive syphon jet, would comply with the requirements.
In the case of the foregoing plans of a hotel, used as an example, there is nothing on the drawings to show the location of the ground work, or grade at which the pipes will be run. The symbols show that cast-iron hub and spigot pipe is to be used, but give no indication as to its weight or grade, whether coated or uncoated, or how the lengths will be made tight. Nothing is shown either on the plans or details which will throw any-light upon the manner in which pipes, both the horizontal drains buried in the ground and the vertical stacks of soil, waste and vent pipes, will be supported; how they will be made tight where they pass through the roof; what means will be employed to connect lead pipe to the cast-iron stacks; the manner or kind of yard drains to use, and whether the drainage system is to be water and gas tight. A "fosa moura" is shown, but there is nothing to indicate what it is made of, how constructed, or by what contractor the work will be performed.
By referring to the following specifications, which were prepared to accompany the plans, all these points are made clear, and by studying the layout on the plans, carefully, in connection with the specifications, it will be found that there is no question which can arise regarding the system of drain pipes or water supply that is not answered in the specifications. That is the crucial test in specification writing. If there is any uncertainty as to what material will be required to install the plumbing system, or any doubt as to the quality of materials or method of installing the work, something is lacking either on the drawings or in the specifications, and the layout should be studied until the lacking element is discovered and incorporated where it belongs.
The layout of pipes in the bathrooms shows unmistakably the two-pipe system of plumbing with syphon traps, and indicates in what manner the several pipes are to be run; also, their several sizes. There is nothing on the drawings to show what weight of lead pipe will be used, how the joints shall be made and how the closets and slop sinks will be connected to the drainage system. These several points, however, are fully covered in the specifications, so that, so far as the drainage system is concerned, there is nothing which an estimator or contractor cannot learn by a reference to the plans and specifications, and nothing is left to be done "according to the direction of the architect," a provision which cannot intelligently be estimated on.
It will be observed that, while the water-supply pipes can be traced on the plans from where the service pipe enters the building to where the various fixture branches are connected to the fixtures, there is nothing on the drawings to indicate whether the pipes and fittings shall be iron, copper, brass or nickel-steel; what weight of pipes shall be used; how the joints shall be made; where the pipes on the ground floor will be located; what sizes shall be used; how they will be supported and at what grades. Meters and a filter are shown, but the kinds or makes are not indicated. The suction tank is outlined, but whether of wood, iron or other material cannot be learned from the plans, nor can the size, capacity and make of pump, hot-water tank or water heater. Valves are indicated, but the kind of valves to use cannot be ascertained from the plans, nor can the kind of house tank to be used on the roof be fully told from the details, although a fair idea may be obtained. All this information which is lacking in the drawings should be incorporated in the specifications, and in the following example of specifications which accompanied the plans, these points are fully covered, as may be seen by a careful reading. The fact cannot be too forcibly pointed out that a contractor estimates only on what is shown on the drawings or mentioned in the specifications. He is justified in believing that the one who laid out the plumbing plans and wrote the specifications was competent, knew what he wanted, and had incorporated everything in his drawings and specifications; and if anything which might be considered essential to the work be omitted, he is justified in believing that the omission was intentional, and in estimating accordingly.
If, however, there is an indication either in the plans or specifications which leads the estimator to believe that something was intended, although not fully mentioned, he is put upon inquiry, and should make sure before proceeding with his tender. The architect, on the other hand, when called upon to verbally explain something in either the drawings or specifications which is not clear, or which when construed together do not explain the point, must know that something is lacking and should correct the plans and specifications to make clear the lacking or ambiguous requirements.