Operable Partitions

Consider Sound Control
Sound Transmission Class (STC)
Hufcor Sound Credentials
On-Site Testing

Consider Sound Control

Determining the amount of sound control you will need is one of the most important considerations when you are evaluating operable and other styles of movable partitions for your facility. Give some thought to determining what types of activities will be held in the room(s). A Sunday school classroom will require lower sound control requirements than a banquet room. It's important to note that the folding walls won't perform to expectations if the room in which they are located does not have a sound rating equivalent to that of the partitions.

Sound Transmission Class (STC)

Operable walls are classified for their effectiveness in reducing transmitted sound by a "Sound Transmission Class” (STC) rating based on test performance in an accredited acoustical laboratory under the ASTM E90 Standard Test Method for Laboratory Measurement of Airborne Sound Transmission Loss of Building Partitions and Elements.

The following chart will give you a rough idea of what the various STC ratings mean.

Acoustical experts agree that the human ear cannot discern the difference between 1 or 2 STC points. Your operable wall supplier may suggest that you consider an STC rating that is +1 or -1 from a published STC rating. The human ear cannot detect the difference, and you may be able to save money doing so.

The higher the STC rating, the higher the price of the partitions. STC ratings are achieved by adding various combinations of gypsum, steel, and insulation to the panel faces and inner cavity. The partitions' perimeter sound seals and closure method are also important for sound control.

However well designed and rated the partition, it won't be able to stop sound from leaking into the adjacent space if the room wasn't designed to control sound. When specifying the STC rating of the partition for your facility, make certain it is equivalent to the rating of the room or you won't achieve the sound control you were expecting. Sound follows the path of least resistance and can leak into adjoining spaces through an open plenum above the partition, through non-sound rated ceiling tiles, gaps around light fixtures, through HVAC systems, etc.

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We Have Sound Credentials

Hufcor built an acoustical testing laboratory in 1969 that is in use to this day. The laboratory enables us to continually test various panel and perimeter constructions to determine their acoustical ratings.

Our acoustical lab is accredited by the National Voluntary Laboratory Accreditation Program (NVLAP™). The laboratory and our testing procedures undergo an annual audit by the NVLAP authorities to make certain we follow their strict testing procedures and our equipment meets NVLAP standards.

Although not required, our sound tests are also witnessed by an independent Professional Engineer. This is additional assurance that the product was tested following the ASTM E90 test standards and achieved the published result.

On-Site Testing

In addition to conducting ASTM E90 tests, we are accredited for performing Noise Isolation Co-Efficient (NIC) field tests under the ASTM E336 Standard Test Method for Measurement of Airborne Sound Attenuation between Rooms in Buildings. NIC calculates how the partition performs when it is installed in the facility. It will also identify areas where there may be sound leaks around the partition. Our state-of-the-art equipment and experienced technicians are available to perform on-site sound tests.

For more about acoustics and operable partitions, visit Acoustics Education. Our Freedom from Distraction brochure explains STC, NIC, flanking paths, and more. Acoustics Education also has information about our AIA continuing education program, How to Optimize Acoustical Performance in Rooms with Operable Partitions. Among other things, the program will teach you how to read an acoustical sound lab report and items to consider when designing a room for use with operable partitions.

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