What is an STC Rating and what is the difference between STC 28 and STC 57?
STC stands for Sound Transmission Class. STC ratings are a numbered rating system used by the building design industry to define how well a partition stops sound from transferring through the partition. An STC of 28 is considered a poor rating as loud voices can be heard and fairly legible between rooms divided by a partition with an STC rating of 28. An STC of 57 is considered an excellent rating as loud voices can only be faintly be heard, if heard at all and conversations cannot be understood. Rough rule of thumb is that the sound is cut in half for every 10 point increase in the STC rating.


Do buildings with curtain wall facades meet minimum STC requirements of the International Building Code and Health Care Construction Guidelines if the partition walls terminate at an exposed mullion? What about concerns about confidentiality and HIPAA guidelines?
Codes vary depending on building type and use. Consult with a licensed design professional or proper code official for project specific questions and answers.

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