Ceiling Attenuation Class

This is a rating value for the efficiency of the ceiling as a barrier to airborne sound transmission between adjacent rooms when the dividing wall doesn't connect with the structural ceiling.

35 is a typical CAC for offices.


A ceiling system with a CAC < 25 is consider low performance, whereas one with CAC > 35 is high performance.

Reference

ASTM E1007 Field Measurement of Tapping Machine Impact Sound Transmission through Floor-Ceiling Assemblies and Associated Support Structures

ASTM E1111 Measuring the Interzone Attenuation of Ceiling Systems

ASTM E1414 Airborne Sound Attenuation Between Rooms Sharing a Common Ceiling Plenum

ISO 140, Part 9 Laboratory Measurement of Room-to-Room Airborne Sound Insulation of a Suspended Ceiling with a Plenum Above

See also: Articulation Class, Sound Transmission Class.

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Subjects: Noise & Vibration