Hush Isolation Board


The Hush Isolation Board is available in two varying sheet sizes.

  • 2′ x 4′ x 1″
  • 2′ x 4′ x 1.5″
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Hush Isolation Board

In situations where office spaces share a common plenum, often the walls do not extend fully to the floor/ceiling structure above. Despite the acoustical integrity of wall partitions or ceiling systems, undesired sound can travel through non-ducted plenum spaces and return-air grilles.

The Hush Isolation Board System effectively addresses the challenge of airborne sound transmission flanking above suspended (drop) ceilings and over interior partition walls. While the common practice of an open plenum above drop ceiling grids reduces return-air duct construction costs, it unfortunately compromises sound transmission, speech privacy, and workplace comfort. Sound attenuation through two layers of ceiling tiles, whether from office to office, boardroom to open office areas, or healthcare examination rooms to waiting rooms, typically achieves a CAC rating of around 35 dB. This rating drops further when a return-air register (egg crate grill) is present. The specified STC rating of a partition wall assembly becomes irrelevant when sound flanks through the suspended ceiling and over the incomplete partition wall. The Hush Isolation Board barrier offers a solution that is quicker, easier to install, and less disruptive than extending gypsum wallboard (GWB).

Uncontrolled noise and compromised speech privacy can negatively impact productivity. The Hush Isolation Board system effectively blocks the space between the top of the partition wall and the structure above without impeding air distribution. It is an easy-to-install, effective barrier that ensures acoustic privacy.


It is advisable to use our Soundproof Seam Tape between the seams of each Hush Isolation Board sheet and our QuietSeal Pro around the perimeter of the Hush Isolation Board “wall.” For a comprehensive installation manual, please contact us.

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 comprises two 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


2′ x 4′ x 1″, 2′ x 4′ x 1.5″

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