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Optimize Sound Insulation/ Blocking

Your walls are for sound insulation and blocking, ceilings leak a lot of noise.

Download Optimized Acoustics™ Blocking Brochure

Sound insulation and blocking should be left to walls, not to an acoustic ceiling.

Before you stop the walls under a suspended acoustic ceiling instead of extending them all the way up, think about if you’re making a shortsighted, budget-driven compromise or a sound decision for the usability of that building throughout a long lifetime.

The impact of poor acoustics

Post-occupancy building surveys show that the number one dissatisfaction with buildings is their acoustics – and more specifically, sound privacy. Those low scores relate to the use of open spaces, but they relate to poorly designed, private rooms, too.

People don’t expect speech privacy when they are in a large open area full of people. But, when they enter a private room and close the door, their expectations for sound privacy change a lot. The problem is that whether or not they will have their expected privacy is completely out of sight. It depends on if you decided to compromise the architecture – inside the walls and above the ceiling.

Before you do that, think about the weight of a wall compared to that of an acoustic ceiling panel. Think about how solid and massive that wall is compared to a lightweight acoustic ceiling full of holes for lights and air devices. The ceiling is no match. That’s why building standards, guidelines, and rating systems require full-height walls with high Sound Transmission Class (STC) ratings.

What is sound insulation?

Sound insulation, also referred to as sound isolation, occurs when a massive and nonporous architectural surface or assembly, such as a concrete slab or multi-layer gypsum board wall, reflects sound energy.

Because the sound reflects off the surface, very little sound transmission into adjacent rooms occurs. Sound insulation helps to provide sound privacy and speech privacy.

Rockfon’s Optimized Acoustics™ design process utilizes full-height walls with the appropriate noise blocking sound capabilities or lightweight acoustic plenum barriers combined with our stone wool ceilings to ensure speech privacy.

RFN-NA, optimized acoustics, sound insulation graphic

Total sound insulation must address multiple noise sources above, below and next to rooms and the many possible paths the noise can travel.

Sound insulation in building standards, guidelines and rating systems

 More and more building types and room types must now comply with more stringent sound insulation criteria in standards, guidelines and rating systems.

  • Guidelines for the design and construction of healthcare facilities, published by the Facilities Guidelines Institute (FGI) , require that "sound insulation shall be considered for all demising construction separating occupied spaces."
  • The WELL Building Standard typically used for commercial office buildings states that “noise from adjacent spaces can be disturbing to building occupants” (feature 81) and can negatively impact the human immune and nervous systems.
  • The Collaborative for High Performance Schools (CHPS) emphasizes that "student learning suffers in acoustically poor environments" where "excessive noise negatively affects speech communication" (EQ14.0). Minimum sound insulation performance for all learning spaces is required.

How is sound insulation defined and measured?

The amount of sound insulation required between rooms in building standards, guidelines and rating systems is defined in one of two ways – either by the minimum Sound Transmission Class (STC) of a full-height wall or by the minimum Noise Isolation Class (NIC) of the whole architectural room enclosure after construction. Ceiling Attenuation Class (CAC) is not recommended becuase it is associated with an unacceptable design approach.

Sound Transmission Class (STC):

STC is a laboratory-measured rating of the sound insulation performance of a wall assembly. An STC rating also can be used for doors, windows and floor/ceiling assemblies. Higher values indicate higher levels of sound insulation between rooms. To determine the appropriate STC of a wall, consider each room’s use, the occupant’s sensitivity to noise and the amount of noise being generated. Building standards, guidelines, and rating systems typically require STC ratings of 40, 45 or 50. Some more critical conditions require values above 50. If a wall has an STC rating requirement, it must be full-height from floor to floor or to the roof, and cannot stop at the height of a suspended ceiling leaving an open plenum. STC ratings are determined according to ASTM E90 standard.

Noise Isolation Class (NIC):

NIC is a field measurement of the total sound insulation performance between two rooms after construction is complete. Higher values indicate higher levels of sound insulation between rooms. NIC accounts for all sound paths through walls, doors, windows, and penetrations. NIC is used in some building standards, guidelines and rating systems instead of STC because NIC considers all sound paths and better represents what people will experience in the space. NIC values of 35, 40 or 45 are typical in normal applications. NIC ratings are determined according to ASTM E336 standard.

Ceiling Attenuation Class (CAC):

CAC indicates a suspended acoustic ceiling’s ability to block sound traveling through a plenum when the wall does not extend full height. High CAC values indicate higher levels of sound insulation between rooms. Suspended acoustic ceilings typically have CAC ratings between 20 and 35. Some can achieve CAC 40 or slightly higher. When light fixtures and supply- and return-air grilles are installed, the ceiling system CAC rating decreases ten points. CAC is not used in most building standards, guidelines and rating systems because suspended acoustic ceilings alone are not able to provide an acceptable level of sound insulation between rooms. CAC ratings are determined according to ASTM E1414 and ASTM E413 standards

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Understanding the reality of sound insulation inside buildings and how to block sound between rooms