STC RATINGS FOR MASONRY WALLS

STC ratings for masonry/CMU walls is based on weight of the block and whether the cells are filled or not and what material it is filled with.

Estimated STC Ratings for CMU Walls

Wall Thickness, in.	Hollow Units		Grout Filled		Sand Filled
	Weight	STC	Weight	STC	Weight	STC
4	20	44	38	47	32	46
6	32	46	63	51	50	49
8	42	48	86	55	68	52
10	53	50	109	60	86	55

The STC rating of a CMU wall can be estimated based on its weight using the following formula:
    STC = 0.18W + 40
    where W = pounds per square foot (psf)

This information is provided as a tool to help estimate. The estimate could easily be off by as much as +/- 4 dB. There are numerous other issues that need to be addressed to get a more accurate calculation. Therefore, hiring a professional acoustical consultant would be essential. Click here to find an acoustical consultant in your area.


Rules of Thumb
Recommended Ratings
Weaknesses - What You Should Know
The difference between STC and NRC
STC Ratings for Various Wall Assemblies
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