Hush Isolation Board


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Hush Isolation Board & Return Air Silencers

When office spaces share a common plenum, most often the walls do not continue all the way to the floor/ceiling structure above. Regardless of the acoustical integrity of wall partitions or ceiling systems, unwanted sound (noise) can travel through non-ducted plenum spaces and return-air grilles.

The Hush Isolation Board System solves the problem of flanking airborne sound transmission above the suspended (drop) ceilings and over interior partition walls. The standard practice of an open plenum above the drop ceiling grid has provided for much lower cost return-air duct construction – unfortunately at the expense of sound transmission, speech privacy and work-place comfort. Sound attenuation through two layers of ceiling tiles from office to office or boardroom to open office areas or health care examination rooms to waiting rooms will typically only achieve a CAC rating of approximately 35 dB. Even less when a return-air register (egg crate grill) is present. The specified STC rating of a partition wall assembly is irrelevant when the sound-flanking path between rooms is through the suspended ceiling and over the incomplete partition wall. The Hush Isolation Board barrier solves this problem with a product that is quicker and easier to install and much less messy than the installation of gypsum wallboard (GWB) extension walls.

Uncontrolled noise and lack of speech privacy can irritate, distract and affect productivity. The Hush Isolation Board system blocks the area between the top of the partition wall and the structure above without interfering with the air distribution. It is an easy to install effective barrier that provides acoustic privacy.

Installation: It is recommended that you use our Soundproof Seam Tape between the seams of each sheet of Hush Isolation Board and our Green Glue Sealant around the perimeter of the “wall” of Hush Isolation Board. For a full installation manual please contact us by phone or email.

Return-Air Silencers solve the problem of HVAC return-air ensuring the acoustic treatment “does no harm” to the HVAC system while maintaining acoustic isolation through the Hush Isolation Board barrier

The System:

The Hush Isolation Board system consists of 2 components:
1. A partition-wall extension board sound barrier; made of a 25 mm (1”) thick foil-faced high-density rigid mineral fiber panel, that meets Class-1 fire rating.
2. A prefabricated Return-Air Silencer made of a 28 Ga. galvanized metal housing to ensure structural integrity and Class-1 fire rating, is lined with a 50 mm (2”) thick high-density rigid mineral fiber board. The airflow face of the mineral fiber board is covered with a Class-1 fire rated non-woven, non-respirable acoustic liner


• Enhances speech privacy and confidentiality

• Fast and easy field installation

• Will not interfere with HVAC return-air flow

• Does not encumber the installation of data cables

• LEED investment (virtually 100% recyclable)

Physical Properties:

Compliance and Performance: ASTM Mineral Fibre Block & Board Termal Insulation Type IVB, Complies MEA Approval New York City Approval 333-97-M

Mineral Wool: ASTM E 136Behavior of Materials at 750°C (1382°F) Non-Combustible CAN4 S114 Test for Non-Combustibility Non-Combustible ASTM E 84 Surface Burning Characteristics Flame Spread = 0 (UL 723) Smoked Developed = 0 CAN/UIC S102 Surface Burning Characteristics Flame Spread = 0 Smoked Developed = 0

Maximum Service Temperature: ASTM C411 Hot Surface Performance In Compliance with ASTM @ 650°C (1200°F)

Foil Facing Flame Spread: UL 723 / ASTM 84 Foil Side = 10 Paper Side = 30 Smoke Developed: UL 723 / ASTM E 84 Foil Side = 0 Paper Side = 5


Office Buildings, Doctors Offices, Dentist Offices, Therapy Office, ect.

Additional information

Weight N/A
Dimensions N/A

Privacy Board, Return Air Silencer