There are within the Movable Wall System industry, several types of acoustic sealing systems located on the vertical and horizontal panel edges of each panel as well as interfacing with permanent building walls. These seals are indispensable components that play a pivotal role in effective sound control across the panel system. In the movable wall industry, there are a diverse array of seal options and technologies, each with distinct features (negative and positive), benefits and operational characteristics.
Initially It is crucial to understand two points about movable wall system panel seals from the start. First, panel seals are not designed to compensate for building deflection. Their capacity to do so is limited, and they should never be relied upon for this purpose. Instead, the structural designer must account for deflections by ensuring the structural steel design has zero deflection. Second, adhering to ASTM E-90 for laboratory sound testing and ASTM E-557 for architectural design and installation is vital. Following these standards as closely as possible will guide and ensure the successful acoustic performance of movable wall systems in the field.
Without well designed, robust, and properly functioning acoustic seals, sound can easily bypass the movable wall panels, through/creating flanking paths that compromise the overall acoustic performance and negate the primary benefit of sound control. They are the prime enablers of the basic function that movable walls are expected to provide: If the seals do not work then the entire system from an acoustic perspective is compromised.
Seal Locations
Acoustic seals are categorized by their location and function and selected and designed to address potential sound leakage around and between panels or permanent building walls.
Horizontal Seals: Located at the top and bottom edges of each movable panels, these seals create a barrier between the panel and the overhead structure and/or track system as well as at the base to create a barrier between the panel and the floor.
Vertical Seals (Astragals): Located along the vertical edge of each panel, these seals ensure a tight acoustic seal between panels.
Perimeter Seals: These seals are specifically designed to seal the movable wall system to the perimeter building walls or other fixed elements (columns, pocket doors etc.) at the ends of the partition run preventing sound from flanking around the entire wall assembly.
Types of Horizontal Acoustical Seals
Fixed Sweep Seals: The original panel seal, the simplest and least expensive but rarely used. They are composed of flexible resilient materials such as vinyl or rubber, configured as “fingers” or “bulb” shapes. Their operation relies on “continuous” contact with the ceiling soffit/track or the finished floor. The seals are fixed in place, no operating mechanisms with constant pressure against the adjacent surface. They have notable limitations. Overtime they will wrinkle and are susceptible to wear and tear due to constant friction against the building interface during panel movement. Much friction is created which makes panels difficult to move. Aesthetically they are not pleasing, will become unsightly as they age and will have to be replaced and available in a limited number of colors.
Manually Operated Retractable Seals: Manually operated or mechanical seals” are located at the base of each panel and sometimes both top and bottom creating a barrier. When activated they compress against the contiguous panel surfaces and prevent sound from flanking over and under the panels.
Top and Bottom Mechanical Seals: Horizontal seals are located at the top and bottom edges of each movable wall panel, creating a barrier between the panel and the floor/ceiling. Their primary function is to compress against these surfaces, preventing sound from flanking over or under the panels. Each panel has an internal mechanism operated by a handle or key inserted into the panel edge that extends or retracts the mechanical seals. The seals are usually made from rubber or vinyl as part of an aluminum extrusion. Simple to operate and cost effective.
Automatic/Motorized Top and Bottom Manual Retractable Seals: Top and bottom retractable “automatic” or “electric seals” are available. These systems eliminate the need for manual cranking, making setup and retraction quicker and more consistent. The manual “automatic” seals are activated by pushing one panel against the next. An internal “cam” system activates base and/or top seals without the need for cranking or any type of manual activation. “Electric top and/or base seals are similar in operation, but they are set in place often by the push of a wall mounted push button system.
Vertical Seals (Astragals): Vertical seals are found along the vertical edges of adjacent movable wall panels. These seals are critical for preventing sound from passing through the narrow gaps where panels meet. Typically, one edge of a panel will have a male profile while the adjacent panel will have a female profile. As panels are brought together these profiles interlock and internal gasketing will compress in several surfaces to form a tight acoustic barrier. Some manufacturers may also incorporate a magnetic strip in the panel edges which will better draw the panels together and seal the panels more securely.
Interface Seals (Perimeter Seals): Interface seals refer to the seals where the movable wall system meets the permanent building structure – the adjacent fixed walls, the floor, and the ceiling. These seals are crucial for preventing "flanking sound," which is sound that travels around the movable wall rather than through it. Jamb Seals: These are seals located at the perimeter fixed walls where the movable wall system terminates. The end panel of the movable wall system will typically extend into or compress against a jamb seal to create a tight connection with the existing wall. Often a compressible seal or gasket built into the jamb assembly. Some systems might use an expandable closure panel with a telescopic sleeve to seal tightly against the wall jamb.
Acoustic seals are not merely accessories but fundamental components that dictate the acoustic performance of movable wall systems. If one analyzes the efforts of all manufacturers over the years it reveals a continuous evolution in seal technology driven by demands for enhanced acoustic performance, ease of operation and integration of aesthetics. Adherence to ASTM Standards (E90 & E557) in non-negotiable for ensuring the intended performance of all movable wall systems. E90 provides the benchmark for laboratory- sound transmission loss and the specific seals used in these tests must be replicated in actual installations.
