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Section 5 - Installation
5.1.1 Hangers
5.1.1.1 Buildings of construction group I. -For requirements see Figs. 2A and 2B.
5.1.1.2 Buildings of construction group II. -Every other hanger supported from wood members shall be attached by two 1/4" diameter through bolts or clinched nails. The remaining hangers shall be attached as described above or by two 1/4" diameter barbed anchor nails 2 1/4" long with oval heads. All bolts and nails shall be at least 2 in. above the bottom of the wood members.
5.1.1.3 Spacing. -Hangers for carrying channels shall be spaced at most 4'6" on centers.
5.1.1.4 Minimum sizes and quality. -Hangers for suspending carrying channels shall be a minimum of 1/4" diameter galvanized steel rods or flat bars at least 1" x 1/8".
5.1.1.5 Use of existing hangers. -Existing hangers may not be used unless they comply, or are made to comply, with all the above provisions relating to hangers.
5.1.2 Carrying channels
5.1.2.1 Leveling requirements. -Carrying channels shall be installed so that they are level within 1/8 in. in 12 ft. leveling shall be performed with the supporting hangers taut. Local kinks or bends shall not be made in hangers as a means of leveling the carrying channels.
5.1.2.2 Attachment to hangers. -Carrying channels shall be attached to the hangers in a manner that will prevent any vertical movement or rotation.
(See Figure 2A and 2B)
5.1.3 Main runners
5.1.3.1 Leveling requirements. -Main runners shall be installed so that they are all level within 1/8" in 12 ft. Leveling shall be performed with the main runner in firm contact with the carrying channel.
5.1.3.2 Attachment to carrying channels. -Main runners shall be attached to the carrying channels in a manner that will prevent any vertical movement or rotation.
5.2 New suspended ceilings below existing suspended ceilings
5.2.1 Buildings of construction group I. -In buildings of construction group I not more than one existing suspended ceiling may be retained above the new suspended ceiling. All other existing ceilings must be removed. Where an existing ceiling is retained, the new main runners shall be supported directly from the carrying channels adjacent to the hangers.
5.2.2 Buildings of construcion group II. -In buildings of construction group II, all existing suspended ceilings shall be removed prior to installation of new suspended ceiling. 5.2.3 Existing hangers. -Existing hangers shall not be used for new suspended ceilings unless found to be in sound structural condition and comply with all the requirements of this standard relating to hangers.
5.3 Ceiling fixtures
5.3.1 General. -Fixtures installed in acoustical tile or lay-in panel ceilings shall be mounted in a manner that will not compromise ceiling performance. Figures 3A, 3B, and 3C are to be used as a guide.
5.3.2 Maximum fixture weights. -Fixtures exceeding 80 lbs. in weight shall be supported independent of ceiling suspension system. Fixtures wieghing 80 lbs. or less may be supported from the carrying channels. Fixtures weighing 50 lbs. or less may be supported from the main runners.
5.3.3 Eccentric loading. -Fixtures shall be installed so that the main runners or carrying channels will be eccentrically loaded unless suitable accessory devices (Figs. 3A, 3B, 3C) are employed and the main runner and/or carrying channel design provides for the torsional stresses.
5.3.4 Plans. -The plans shall show the necessary details of the acoustical ceiling to satisfactorily identify the number, size, spacing, location, weights, and types of fixtures and means employed to comply with this section.
Figure 2A.
Figure 2B.
Figure 3A.
Figure 3B.
Figure 3C.