Sound Transmission Class (STC)

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 entry 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 doorglass configurations. All of the doorglass samples were 22" x 64" except the sliding patio door blind which was 33" x 74". 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.

Family	Configuration	STC	Comment
Deco	Decorative glass with caming	31	Third party tested (1.39 M) Adobe PDF
1-lights, grilles between glass, external grilles	1/2" IG, clear glass 1-light, 1/4" air space, Intercept® spacer	26	Third party tested (1.39 M) Adobe PDF
	1/2" IG, clear glass, external grille, 1/4" air space, Intercept® spacer	26	Third party tested (1.39 M) Adobe PDF
	1" IG, clear glass 1-light, 3/4" air space, Intercept® spacer	28	Third party tested (1.39 M) Adobe PDF
	1" IG, clear glass, grilles between glass, 3/4" air space, Intercept® spacer	30	Third party tested (1.39 M) Adobe PDF
	Simulated divided light, grilles between glass with external grilles, 3/4" air space, Intercept® spacer	30	Third party tested (1.39 M) Adobe PDF
Sound Suppression	1" IG 1-light with laminated glass	34	Third party tested (183 K) Adobe PDF
Blinds	Triple-glazed, grilles between glass blind, with Intercept® spacer, slats lowered and closed	34	Third party tested (394 K) Adobe PDF
	Dual-glazed blind, with Intercept® spacer, slats lowered and closed	32	Third party tested (394 K) Adobe PDF
	Sliding patio door blind, Intercept® spacer, slats lowered and closed	28	Third party tested (394 K) Adobe PDF
Door and window reference information	3' x 7' steel door, 1-3/4" thick with polyurethane core	26	From HUD Noise Notebook*
Door and window reference information	30" x 48" aluminum clad casement window, 1" IG with 1/8" panels	29	From HUD Noise Notebook*

Sound Transmission Class (STC)

Decorative Door Glass

Enclosed Blinds

Clear Door Glass

Definition

STC Values

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

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