One element or product in a flexible space cannot achieve sound isolation on its own. In one of our latest blog articles, we explored 8 different and innovative interior design products to help manage acoustics in open or flexible spaces, including operable partitions. But these elements need a strong foundation to be effective; an operable partition’s acoustic performance can be impacted by the construction of its surroundings. Which is why we’ve put together a list of 5 things to consider during construction to ensure the acoustic success of your flexible space as per ASTM E557.
What is ASTM E557?
ASTM E557 is a best practices guideline for the construction surrounding an operable partition. Whether in a school classroom, auditorium or gym, hotel ballroom, or corporate meeting room, ASTM E557 guidelines ensure that acoustical performance in flexible spaces is optimized. Produced by the American Society for Testing and Materials, (ASTM)—an international standards organization for materials, products, systems, and services—these guides are reviewed and published every year and operate globally.
5 Construction Recommendations for Acoustic Isolation in Spaces Subdivided by Operable Partitions
1. Find Possible Sound Flanking Issues
Before construction of the space even begins, you need to check your design for potential sound flanking. When assessing for sound flanking, you’re looking around and at the operable partition to see where sound can potentially leak through to the adjacent room. Some typical areas around the operable partition where sound flanking may occur include the fixed walls, ceilings, floors, ductwork and electrical outlets. Once you’ve assessed where there is a risk for sound flanking, you can then reduce or eliminate the risk. As mentioned, the acoustic performance of an operable partitions can be either improved or hindered by the surrounding structure or space; it doesn’t make much sense to put a 60 STC operable partition in a room where the fixed walls, floors and ceilings are only a 30 STC.
2. Prevent Noise Transmission from Under the Operable Partition
Floors and floor coverings are areas for potential sound flanking. If the floor is raised, then an acoustical barrier should be placed in between the elevated and sub floors, and the barrier must be aligned with the operable wall. The acoustic barrier requires the same STC, if not higher, of the operable partition selected for the space.
Floor seals where the bottom of the operable partition meets the floors are also an effective way to reduce noise transmission, but they perform best when sealing against a flat solid surface, instead of carpet. A carpet, by design, is full of air gaps between the fibers, which allow sound to travel underneath the operable partition’s bottom seals, even more so for partitions with 1.5” to 2” wide drop type seals. For spaces outfitted with carpeting, install an in-slab (also known as a standard terrazzo "T" dividing strip) in the subfloor directly under the operable partition to reduce sound vibration through the solid floor. Take it a step further by omitting carpet where the operable partition’s bottom seals would touch the floor and by installing a smooth strip instead. Although this would create a break in the carpet’s continuity, the smooth strip would improve the acoustical performance of the partition.
3. Prevent Noise Transmission from Over the Operable Partition
Noise can also creep over the top of an operable partition. Ceiling plenum (the space above the top of the operable partition) up to the bottom of the slab or underside of the roof must have an acoustical tight barrier. This will prevent noise from one space travelling over the top of the operable partition into the adjacent room. For this to work, the plenum barrier above the operable partition must be aligned with the partition, and it must have acoustic properties equal to or better than that of the operable partition chosen. To ensure top performance, the acoustic barrier would need to extend from the ceiling to the slab with no gaps around penetrations made by the HVAC, sprinklers, and the like.
4. Assess HVAC Systems that are Connected Between Rooms
Connected HVAC systems provide an easy way for noise to enter isolated rooms. If HVAC ducts link two spaces or more, the interior duct should be lined with absorptive material or a silencer. Watch out for air gaps around the ducts in the ceiling plenum above the operable partition since unsealed air gaps will also leak sound between adjacent rooms. Ductwork that passes above the operable partition should be rated 10dB higher than the acoustic rating of the operable partition.
5. Consider the Surrounding Permanent Walls
Adjacent fixed wall construction must also have acoustic properties equal to or better than of the operable partition within the room. For track-dependent operable partitions that have wall jambs, the surrounding fixed walls should be treated with acousical breaks and proper sealant.
Today, operable partitions systems can achieve sound transmission coefficient (STC) ratings as high as 60 STC with a 66 STC panel test. For the surrounding walls do the same or better, they would need to incorporate a decoupled stud attachment, multiple layers of gypsum board and a dead air space when constructed.
Why Does Sound Isolation Matter?
In corporate and educational facilities, unmanaged noise in open or flexible spaces can impact occupants’ wellbeing by increasing stress or fatigue and by reducing productivity. In some cases, noise complaints and poor acoustics can impact businesses’ revenue, especially in the hospitality industry. On the flip side, spaces that do make these acoustical construction considerations can see an increase in revenue, as observed in a 2019 Ecophon case study of a restaurant in Spain. Just like how you would consider people’s movement throughout a space, you need to also consider how noise may travel and disrupt those same occupants.
While the ASTM E557 is often referenced in the architectural specification, many of these best practices are overlooked or ignored during construction. When this happens, the acoustical performance of the whole flexible space is often less than it could have been thereby affecting the wellbeing and experiences of occupants.
Learn More About Architectural Acoustics
Has this article piqued your interest? Skyfold offers a 1 hour continuing education course called “Mastering Architectural Acoustics in Flexible Spaces.” AIA and IDCEC members will earn 1 HSW learning unit for this accredited course. Click here to schedule yours today (also available as a webinar).
Published August 25, 2020