Acoustical performance of building products, components and systems is an important consideration for engineers, specifiers and building owners. This is especially true in highly populated cities, areas around highways, railroads, airports and high density residential zones. The demand for efficient noise reducing building in these areas are rising constantly.

Using the latest sound absorbing techniques and materials, Republic’s engineering professionals have developed a superior sound transmission class (STC) rated assembly consisting of a noticeably lighter weight door (approximately 25% less than current market products) along with standard “rabbeted” hollow metal frames. These assemblies utilize 1 3⁄4" (proprietary) sound-core doors, standard hollow metal frames and a low profile sealing system that is aesthetically pleasing to the eye and easier to install.


A critical factor to understand when specifying acoustic doors and frames is the Sound Transmission Class, or STC rating.

  • The STC rating is calculated in accordance with ASTM E413
  • It’s a single number rating for interior building partitions that are subjected to mid to high frequency noises
  • The higher the number, the better the noise isolation
  • Standard steel doors often have an STC rating in the 25-35 range
  • Specifying a door with an STC rating in the 40s is adequate in most situations, but in settings where sound control is critical, such as an office where confidential meetings are held, doors above STC 45 may be needed

Typical applications

Wherever acoustical performance is required, especially in highly populated cities, areas around highways, railroads, airports and high density residential zones.

Republic Products

See the following Republic products for STC rated applications:

For more information on Republic's STC doors, please see the Republic Technical Data Manual (Pages 27-32).


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