Introduction to Acoustics

408 Part C Architectural Acoustics
Part C 11.5
Angle
restraint
CMU
Set studs 1.3cm
from structure
above
Metal studs
Sound
attenuation
blanket
1 layer GWB
2.5cm min.
air gap
Provide a continuous
bead of acoustical
sealant around ceiling
and floor perimeters
of partition
Fig. 11.30 Cross section of a floor to structural ceiling
double-wall design with a CMU wall
Compressible
filler
Structure
Angle restraint
Sealant or firestop
system at perimeter
on both sides
(as necessary)
Resilient element
Metal channel
One layer GWB
CMU – solid grout
Sealant at perimeter
Floor structure
Structure
Acoustical sealant
at deck flutes where
required
Ceiling
Sound attenuation
blanket
Metal studs
2 layers GWB per side
Provide a continuous
bead of acoustical
sealant around
ceiling and floor
perimeters of partition
Floor structure
Fig. 11.32 Cross section of a single-studded sound insulating
wall meeting a fluted metal structural deck
control is an issue, the STC rating does not address
that and larger air spaces between wall components will
increase the low-frequency noise control effectiveness.
Double-wall constructions are often impractical because
of space restrictions. In these cases, an alternative
to the CMU construction in Fig. 11.30 would be that
shown in Fig. 11.31, in which the air space is replaced
by a resilient element.
When working with gypsum board, Fig. 11.32 shows
a design concept that will provide an STC of at least 50 as
long as it is sealed properly. Note that a fluted structural
deck may provide air gaps at the top of the wall that
would need to be sealed to preserve the noise reduction
effectiveness of the system.
When a room needs to be isolated from the building
structure (which would be the case when structureborne
vibrations cause unwanted noise and vibration
in certain rooms in which sensitive activities are tak-
Fig. 11.31 Cross section of alternate construction to
a double-wall design in Fig. 11.30