After the location of the toilet room has been decided on, and it should be placed as centrally as possible to the floor area, the number of closets should be determined. It is usually found sufficient accommodation if one closet is allowed for twenty people. In planning the toilet room, it is essential, and generally required by law, that the room shall be located on the outside wall, so that windows will open directly into it. If the partitions between the compartments only extend part way toward the ceiling, it is not necessary that each compartment of the toilet room containing a closet should have a window. For instance, referring to Fig. 5, which is a typical arrangement of factory toilets, it is necessary only to provide the window opening into the outside space surrounding the enclosures around the closets. [Illustration: FIG. 5] =18. Material Used for Partitions.=—The partitions of both the compartments and the toilet room are, in factory construction, usually built of 1⅛-inch, yellow-pine, tongued-and-grooved, beaded ceiling, the corners of the partition being braced with 4" × 4" stop-chamfered yellow-pine posts rabbeted to receive the ceiling. In no instance should the partitions be constructed with an enclosed space or concealed work. For hygienic reasons, it is always advisable to provide toilet rooms with waterproof floors, and the brick walls that may partially surround the enclosure should be waterproofed for a distance of at least 1 foot from the floor. The waterproofing commonly employed for the floors is asphalt or _asbestolin_, the latter being a composition that is placed directly on the finished floor and forms a permanent covering about ¼ inch in thickness, and of the nature of the best cork linoleum. In waterproofing the walls, about the only practical method to employ is to give them several coats of an approved waterproof paint. [Illustration: FIG. 6] Fig. 6 illustrates a reasonably cheap and still excellent construction for toilet-room enclosures, the several details of the construction being sufficiently clear without further explanation. =19. Toilet-Room Fixtures.=—In selecting fixtures for the toilet rooms of a factory building, only the most serviceable kinds should be used. In standard work, iron-porcelain siphon-jet closets with overhead copper-lined flushing tanks are employed. The flushing is controlled automatically by the action of the seat, which is always raised by being provided with counterweights. Lids to the closets are never used in factory installation, from the fact that they are readily broken and generally out of order. TYPES OF MILL CONSTRUCTION GIRDER AND PLANK-ON-EDGE CONSTRUCTION