- Solid manual movable wall systems.
- Glass manual movable wall systems.
- Solid demountable wall systems.
- Glass demountable wall systems.
The one common factor that the above wall systems have is “flexibility.” Each provide the versatility to adapt spaces for changing needs but do so in diverse ways. The two factors that most influence which product to use are “price” and “acoustics.” This article will compare the acoustics and estimated costs of each system.
Sound Transmission Class (STC) is the industry standard for measuring a wall system’s ability to block sound. The higher the STC the better the sound isolation. STC values are determined in an independent testing laboratory as per ASTM E-90. In addition, the quality of sound isolation is only as good as the quality of the installation and the acoustic integrity of the wall contiguous construction materials. In general, 1 STC unit is equivalent to 1 Dba of sound. If for example you have an STC 50 wall system, it is expected that the wall system will reduce sound transference of 50 Dba.
For reference purposes with an STC of 45 or less, sound is very easily heard through the wall. STC 46 to 50, loud speech can be heard but not easily understood. STC 51 to 56 provides an elevated level of sound blocking.
Solid manual movable wall systems: Maximum STC values up to 60 depending on panel thickness, core material, mass, and advanced perimeter acoustic sealing technology. A recommended minimum STC value for the most common of applications is 52. Several types of perimeter acoustic seals including interlocking acoustic astragals, fixed (finger-sweeps), manually operated top and/or base or automatic. Steel skins over ½” gypsum board with a vinyl covering. Biggest acoustic problem are imperfect perimeter seals with gaps at floor, ceiling, or panel joints. Flanking paths (sound bypassing the wall and going through ceilings, floors, or adjoining walls.
Typically used in large spaces that require flexible configurations and predictable sound control.
Glass manual movable wall systems: Maximum STC values up to 51 depending on panel thickness and type of glass and thickness used. Laminated glass with dissimilar thicknesses on each side of the panel will achieve the highest STC. The most common STC value specified and used is 44/45. Can achieve higher STC values by increasing panel thickness. Heavier and more rigid frames that reduce vibration will increase STC numbers. Also susceptible to sound leaking around the system (flanking paths).
Aesthetically pleasing. Provide natural light. Moderate to good acoustics.
Solid Demountable Wall Systems: Maximum STC values up to 55 depending on panel construction (materials, thickness, density of insulation). Typically, they have vinyl or fabric covered steel over a gypsum board substrate. Increase panel thickness and increase insulation density for higher STC values. Isolate skins from panel frames to reduce through transmission of sound energy. Sound leaks will occur through shared building elements like ceilings and floors. Also, vibrations through any rigid connections to the adjacent walls and ceilings.
Very cost effective. Good acoustics. Easy installation. Durable with minimal maintenance. Variety of finishes.
Glass Demountable Wall Systems: Maximum STC values up to 50. Double glazed configurations, typically 4” thick. Laminated glass. High performance gaskets and seals around the perimeter. Vary thickness of glass to reduce resonance. Have poor speech privacy due to lower STC values of glass as compared to solid walls. Glass surfaces also reflect sound leading to increased reverberation.
Natural light. Modern appearance. Aesthetically pleasing. High initial cost.
Summary of Acoustic Characteristics and Potential Issues
For maximum acoustic performance, solid moveable walls or solid demountable walls are the most effective achieving higher STC values than any glass system. Glass system acoustics can be improved with double glazing and laminated panels but will always be inherently more limited in STC performance. Better acoustics on all systems can be achieved post-installation through additional acoustic perimeter sealing, the use of sound masking and acoustic treatments. The biggest challenge for all systems involve flanking paths: air leaks, structural coupling, lack of equivalent acoustic materials and qualities in the contiguous construction all of which can be mitigated through careful design and installation practices.
Comparison of Costs of the above systems
Every project is different but on the other hand every project is the same. The base product of each of the above systems is the same with price changes occurring in accessories, covering materials, types of acoustic seals, STC values etc.
As a guide below are some general pricing factors you can use to compare the cost of each of the above systems. Each of the 4 products has a “pricing factor” (PF) that allows a comparison because you have a price on one of the systems.
| System | PF |
| Solid Manual Movable Wall | 1.0 |
| Glass Manual Movable Wall | 2.8 |
| Solid Demountable Wall | 1.6 |
| Glass Demountable Wall | 1.8 |
How to use the PF. Let us assume you have a price of $10,000 on a “Glass Demountable Wall” and you want a comparative price on a “Glass Manual Movable Wall”. Multiply $10,000 by the PF for the “Glass Manual Movable Wall” (2.8) and divide by the PF for the “Glass Demountable Wall” (1.8).
New Price = ($10,000 X 2.8)/ 1.8 = $15,555.
Summary
If acoustic control is the top priority, solid manual movable wall systems and solid demountable wall systems are the best choices. Glass systems, despite their aesthetic appeal and ability to maintain visual connectivity, have lower maximum STC values and are less effective for sound isolation.
If price is the priority, then manual movable wall systems are the best choice.
