is inappropriate to have high CAC rating for
ceilings if walls nullify acoustical benefit.
Where room partitions do not extend to floor or roof
deck above, ceiling plenum path may prevent
acoustical privacy between rooms. Where required to
provide adequate room to room sound attenuation,
entire ceiling assembly including air terminals and
light fixtures should have appropriate Ceiling
Attenuation Class (CAC). Any penetration of ceiling
assembly will destroy integrity of ceiling in this
regard. Verify that other specification sections
and drawings include appropriate data to ensure that
these requirements are met for air terminals and
light fixtures. For standard applications, specify
CAC range of 35 - 39. A ceiling CAC range of 40-44
is recommended for all spaces where speech privacy
is required and that are surrounded or sub-divided
by partitions which do not extend to underside of
floor or roof deck above. For classified conference
rooms, executive offices, teleconferencing rooms and
other occupancies requiring the highest degree of
speech privacy, sound attenuation requirements will
have to be achieved by other means, most likely by
high sound transmission class (STC) partition
extending to the underside of floor or roof deck
above.
**************************************************************************
The ceiling attenuation class (CAC) of the ceiling system shall be [_____]
for [_____] [and _____ for _____] when determined in accordance with ASTM E
1414. Provide fixture attenuators over light fixtures and other ceiling
penetrations, and provide acoustical blanket insulation adjacent to
partitions, as required to achieve the specified CAC. Test ceiling shall
be continuous at the partition and shall be assembled in the suspension
system in the same manner that the ceiling will be installed on the project.
1.3.3
Ceiling Sound Absorption
Determine the NRC in accordance with ASTM C 423 Method of Test.
1.3.4
Light Reflectance
Determine light reflectance factor in accordance with ASTM E 1477 Test
Method.
1.4
DELIVERY AND STORAGE
Materials shall be delivered to the site in the manufacturer's original
unopened containers with brand name and type clearly marked. Materials
shall be carefully handled and stored in dry, watertight enclosures.
Immediately before installation, acoustical units shall be stored for not
less than 24 hours at the same temperature and relative humidity as the
space where they will be installed in order to assure proper temperature
and moisture acclimation.
SECTION 09510
Page 9
Previous Page
