Why is sound transmission between rooms a problem in buildings with glass facades?
Even though the drywall partition between rooms is properly designed and constructed to stop sound, this partition wall terminates into a vertical mullion that supports the curtain wall or ribbon wall glass. This mullion might appear to be solid, but it is actually a fairly lightweight hollow tube. This mullion is not designed to stop sound transfer. When tested in the laboratory, a drywall partition with an STC rating of 57 that terminated into a curtain wall mullion only has an STC of 28 when tested as an assembly.

What are the typical dimensions for the Mull-It-Over Sound Barrier Mullion Trim Cap?
The Mull-It-Over Sound Barrier Mullion Trim Cap was designed to accommodate most curtain wall manufacturer’s standard systems and allows for construction tolerance during installation. The Classic Mullion Trim Cap will accommodate end of partition wall to interior face of glass dimensions between 1-1/4" and 8". A minimum dimension of 7/8" is required from the exposed face of the drywall to the side of the vertical mullion. The Wide and Flush profiles accommodate most other standard detail requirements. Custom extrusions can be provided to accommodate dimensions that do not fall within the standard range. Please contact Mull-It-Over Products for assistance if custom details are required.

Is the Mull-It-Over Sound Barrier Mullion Trim Cap a unique system?
Yes. The Mull-It-Over Sound Barrier Mullion Trim Cap design is unique and is protected by patent numbers 8,572,914 and 8,782,977 for the United States and countries signatory to the Patent Cooperation Treaty.

Our project is unique. What if my partition wall does not terminate at a mullion? What if the wall is angled? What if my project has full height vision glass and sound transfer between floors is a problem? What if I have a folding partition wall that terminates into a curtain wall? What if my curtain wall mullions are deeper than 8"?
Custom solutions for almost any circumstance are available. Call or e-mail for unique solutions.

A building is constructed with high quality drywall partitions that include sound batt insulation, the walls are sealed tight to the deck and power and data outlets were properly offset. If the drywall partition terminates into a curtain wall mullion at the building perimeter and nothing is done to prevent sound from transferring through the mullion, is the performance of the drywall partition compromised?
Yes. Sound will flank around the end of the drywall partition through the hollow mullion and into the adjacent room. When tested as an assembly, a high STC rated partition wall has a low rating of STC 28 when terminated into an exposed vertical mullion.


Get In Touch

Learn how Mull-It-Over can help you with your next project.