320
Ceiling: Dimensions
323
DIMENSIONS (Figure 320-7)
There are only a few generalized rules concerning the dimensions of the
ceiling subsystem. Many of these have already been described in
connection with the basic design; they are summarized in this section for
convenience.
323.1
HEIGHT OF FUNCTIONAL ZONE
The height of the platform above the floor is constant at least in each fire
section and preferably throughout each floor. The functional zone (i.e.,
finished floor to finished ceiling) varies from a recommended height of nine
feet (mainly in the nursing areas) to a recommended height of ten feet in
the support areas of the hospital.
323.2
HEIGHT OF SERVICE ZONE
The platform is suspended below the structural slab at a sufficient
distance to create a service zone approximately eight feet high. (See
Figure 220-6.)
323.3
DEPTH OF CEILING STRUCTURE
A design which minimizes the overall depth of the ceiling structure is
preferred. A depth of 4" excluding the supporting framework is assumed
for preliminary planning purposes. (See Figure 220-6.)
323.4
MODULE
There is no planning grid to which the ceiling subsystem must conform;
partitions can be attached to any point of the platform, though the location
of structural beams presents some constraint. (See Section 333.4.) Their
location will also be limited by the structural grid of the ceiling subsystem
which will make certain portions impenetrable by services. For this
reason, the dimensions of the ceiling structure should be coordinated with
those of the structural beams where possible. (See Section 322.1.1,
Paragraph 3.)
323.5
HANGER SPACING AND DIAGONAL BRACING
Each hanger supports a maximum of approximately fifty to sixty square
feet of platform. The structural beams will determine the hanger spacing in
one direction. This spacing will be 4'6", 5'7-1/2", or 7'6". The width of
secondary subzones for service distribution will probably determine the
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