TM 5-805-4/AFJMAN 32-1090
Table 4-6. Transmission Loss (in dB) of Stud-Type Partitions. (Cont'd)
Improvement A.
1. These values may be added to TL of Type 1 or Type 3 partition if
l/2-in. thick fibrous "sound-deadening board" is installed between
studs and each layer of gypsum board.
2. These values may be added to TL of each type partition if resilient
spring clips or resilient metal channels are used to support one layer
of gypsum board on one side of the set of studs. (For Type 2, delete
the second layer of gypsum board on this side; keep two layers on opposite
side.) No significant additional benefit will result from combining
resilient supports and sound-deadening board under the same layer of
gypsum board.
Improvement B.
1. If full area 3-in. thick glass fiber or mineral wool is loosely sup-
ported inside the air cavity between walls, add these values to TL of
Type 1 or Type 2 partition. Acoustic absorption material must not
contact both interior surfaces of gypsum board (i.e., must not serve as
partial "sound bridge" between walls).
2. If minimum l-l/2-in. thick glass fiber or mineral wool is loosely
supported inside the air cavity, add these values to TL of Type 3 parti-
tion or add one half these values to TL of Type 1 or 2 partition. Follow
precautions of Step B.l above.
Regarding both Improvements A and B.
The combined TL benefits of one type A improvement and one type B improve-
ment can be applied to each of the partition types shown. More than two
of these improvements to one partition will result in no significant
additional TL benefit.
deflection requirement. The hanger system must
for the Type 3 acoustical material must be 0.65.
not have metal-to-metal short-circuit paths around
The estimated TL of a Type 3 floor-ceiling is given
the isolation material of the hanger. Where the
in table 4-14 for a few typical dimensions of
ceiling meets the vertical wall surface, the perime-
concrete floor slab thickness and air space.
ter edge of the ceiling must not make rigid contact
(4) Type 4 floor-ceiling. This floor-ceiling com-
with the wall member. A 1/4-inch open joint
bination consists of a concrete floor slab, an air
should be provided at this edge, which is tilled
space, and a resiliently supported plaster or gyp.
with a nonhardening caulking or mastic or fibrous
bd. ceiling. This combination is for use in critical
packing after the ceiling plaster is set.
situations where a high TL is required. The ceiling
(b) Critical locations. Critical locations re-
should have a minimum 12 lb/ft.2 surface weight
quire special care, Caution: This combination
and the plemum space should be at least 18 inches
should be used only in critical situations, and
high. The estimated TL of the Type 4 floor-ceiling
special care must be exercised to achieve the
combination is given in table 4-15 for a few
desired TL values: full vague floor weight and
typical dimensions of floor slab, air space, and
thickness, no holes through the floor, and com-
ceiling thicknesses.
pletely resiliently supported nonporous dense ceil-
(a) Resiliently supported ceiling. The ceiling
ing. If the plaster of gyp. bd. ceiling is not
should be supported on resilient ceiling hangers
supported resiliently, the TL value will fall about
that provide at least 1/10 inch static deflection
midway between the Type 3 and Type 4 values for
under load. Neoprene-in-shear or compressed glass
the corresponding dimensions and floor slab
fiber hangers can be used, or steel springs can be
weights.
used if they include a pad or disc of neoprene or
(5) Type 5 floor-ceiling. The "floating concrete
glass fiber in the mount. A thick felt pad hanger
floor", as shown on figure 4-4, is a variation that
arrangement can be used if it meets the static
4-12
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