STC (Sound Transmission Class)

STC Definition and Options

STC ratings are single number indicating the sound insulation value of a door or window (including partitions and floor-ceiling assemblies.) A door’s ability to reduce noise is called its sound transmission loss (TL) effectiveness.

 

TL is a value given in decibels (dB) which is determined by measuring sound pressure levels at a certain frequency in the source and receiving rooms.

 

See image using STC 39 as a sample -->

 

These values are fitted to a curve in a method defined by the ASTM E413 Classification Standard for Rating Sound Insulation. The higher the STC value, the better the rating and the better the performance.

Figure 1

Figure 2

Haley offers architectural doors with the following STC ratings, sub components, and gasketing:

 

STC 32- Standard Particle Board Assembly- (1LD1 Core)  APC Bond to Core.

 

STC 32- Lumber Core Assembly- ALC Bond to Core.

 

STC 33- 36 lbs to 40 lbs Core- (1LD2 Core) APC Bond to Core, No Lead, Standard Stiles and Rails.

 

STC 35- 44 lbs to 45 lbs Commercial Density Core- Bond to Core, No Lead, Standard Stiles and Rails.

 

Any unsealed gaps and clearances in door assemblies effectively cancel out the noise reduction benefits of STC rated doors. For example, 1⁄8″ clearances around the edges reduce the effective rating of an STC-52 door to STC-21! 

 

Gasketing’s importance derives from a fundamental property of sound: Sound waves travel through any opening with very little loss. While the amount of air flowing through a gap increases in proportion with the size of the gap (see Figure 1) the size of the gap in a sound barrier does not matter (see Figure 2.) A tiny hole transmits almost as much sound as a much larger gap.

 

STC 40- SLM Stiles and Rails

             1 lb Lead

             1/2" Particle Board Sound Board

             Soundboard

             1/2" Particle Board Sound Board

             1 lb Lead

             Pemko 2005V Threshold, 234V Sweep with Two sets of S88 Gasket.

 

STC 41- SLM Stiles and Rails

             1 lb Lead

             1/2" Particle Board Sound Board

             Soundboard

             1/2" Particle Board Sound Board

             1 lb Lead

             Pemko 2005V Threshold, 234V Sweep with Two sets of S88 Gasket and One Additional set of 319R Seal.