Stc Rating For Concrete Walls

The stc rating of a cmu wall can be estimated based on its weight using the following formula.

Stc rating for concrete walls.

Stc 14 1w equation 1 is applicable to uncoated fine or medium textured concrete masonry and to coated coarse textured concrete masonry. The estimate could easily be off by as much as 4 db. 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. The magenta line in that graph is the standard reference stc contour.

Installing insula tion within a wall or floor ceiling cavity will improve the stc rating by about 4 6 db which is clearly noticeable1. There are numerous other issues that need to be addressed to get a more accurate. When the mass of a barrier is doubled the isolation quality or stc rating increases by approximately 5 db which is clearly noticeable. Simple concrete slabs with density around 2300 kg m 3 and thickness in the range 150 to 200 mm provide stcs from about 53 to 58.

The green line is the performance of the wall. The table below gives representative stc values and mass per square metre for some concrete slabs. 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. Stc hollow with insulation 52 53 56 59 corefoam masonry foam insulationis an excellent product for improving thermal and acoustic properties of walls constructed with concrete masonry units cmu.

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. If your wall graph is closest to a standard stc 35 curve your wall is said to have an stc rating of 35. It does not matter whether the slab is a wall or a floor the airborne sound transmission is the same. For example a thick concrete wall will block more sound than a thin gypsum 2x4 wall.

In the absence of test data standard calculation methods exist which tend to be conservative. Adding green glue to boths side of a wall. The standard requires a minimum laboratory stc rating of 50 for party walls and floor ceilings. Mass is commonly added to existing walls by adding additional layers of gypsum.

A wide variety of stc ratings is available with concrete masonry construction depending on wall weight wall construction and finishes. 1 contains procedures for determining stc values of.