Because coarse textured units may allow airborne sound to enter the wall they require a surface treatment to seal at least one side of the wall.
Stc rating of concrete walls.
Stc ratings for wall floor and window materials and assemblies 3 appendix a stc ratings a 1 walls a 1 exterior a 1 interior a 9 wooden studs a 9 metal studs a 14 floors a 16 wood a 16 concrete a 21 windows a 24 doors a 27 exterior a 27 interior a 29 appendix b references b 1.
Adding green glue to boths side of a wall.
A wide variety of stc ratings is available with concrete masonry construction depending on wall weight wall construction and finishes.
Even in walls made using the same material the thickness is always different.
Due to increased mass poured concrete and concrete blocks typically achieve higher stc values in the mid stc 40s to the mid stc 50s than equally thick framed walls.
If your wall graph is closest to a standard stc 35 curve your wall is said to have an stc rating of 35.
The standard requires a minimum laboratory stc rating of 50 for party walls and floor ceilings.
The stc rating of a cmu wall can be estimated based on its weight using the following formula.
The stc rating does not assess the low frequency sound transfer.
Stc 14 1w equation 1 is applicable to uncoated fine or medium textured concrete masonry and to coated coarse textured concrete masonry.
Walls with a higher stc are better at blocking sound the higher your wall stc the more peace you will enjoy.
1 contains procedures for determining stc values of.
Sound transmission class guidance introduction the noise guidebook.
There are numerous other issues that need to be addressed to get a more accurate.
125 4000 hz is consistent with the frequency range of speech.
The estimate could easily be off by as much as 4 db.
Wall thickness and material.
Helps ensure that partition sound performance matches the promise of sound tests by sealing off spaces at partition perimeters and around cutouts can increase the stc rating of a double layer steel framed partition from 29 to 53 stc an integral part of high performance usg partition designs for attenuation of low frequency sound from machinery and music suitable for use at the perimeter of fire rated wall assemblies for more information see the following brochure.
A drywall wall is different from a concrete one in different properties.
All too often this plenums and suspended ceilings unbaffled ducts window to window outdoors common heating units transoms and air grilles unblocked joist spaces uncaulked wall perimeters ducts piping and fixtures masonry joints.
Adding absorptive material within the partition a partition is given an stc rating by measuring its transmission loss over a range of 16 different frequencies between 125 4000 hz.
Standard method for determining sound transmission ratings for masonry walls tms 0302 ref.
Stc 0 18w 40 where w pounds per square foot psf this information is provided as a tool to help estimate.
The magenta line in that graph is the standard reference stc contour.
