Definition
STC is expressed in decibels (dB) and is used to measure a building material's ability to reduce sound. A higher STC rating translates into more reduction in sound. Laboratory testing is used to measure the resistance of partitions such as walls, windows, or doors to the passage of sound.

The material with the lowest resistance to the passage of sound limits a partition's STC value. Poor construction practices can also nullify a partition's sound reduction properties. Cracks due to improperly fitted doors or windows can be a prime source of sound leakage.

STC values
ODL conducted third party IAS-accredited lab testing on a range of 22" x 64" doorglass configurations. These sound transmission loss tests were conducted in accordance with ASTM E 90. The Sound Transmission Class (STC) rating was calculated in accordance with ASTM E 413. Test results and benchmark values are presented below.

* Source: HUD Noise Notebook chapter 4 supplement, Sound Transmission Class guidance