Architects and acoustical consultants are often faced with situations where they have to meet certain sound isolation goals that are mandated by law. Legally mandated STC’s of 45 or 50 in the field are common. In many cases, these STC’s must be met with fire-rated walls.
For decades, resilient channel has been the logical choice for these applications. It yields high STC’s in lab tests, and is still one of the most inexpensive sound isolation products available. The downside to resilient channel is that it has a long history of problematic field installations. If the channel is “short-circuited”, performance can suffer greatly.
In a series of lab tests, The Green Glue Company explored the impact that damping with Green Glue has on the STC performance of a resilient channel wall - and a short-circuited resilient channel wall. A reference wall with no damping attained STC=52, a Green Glue wall that was heavily short-circuited (16 short circuits on an 8’ x 8’ test wall) attained STC=55 with the same number of drywall layers and type, stud spacing, insulation, channel, channel spacing, etc. Based on this work it seems reasonable to state that Green Glue can eliminate the risk of resilient channel installation failure due to short circuit. Read: Green Glue -vs- Resilient Channel
And so the often-criticized, but still inexpensive, resilient channel has a new ally in the STC game. Green Glue does add to the cost of an installation, but this cost is fractional, and trivial compared to the cost of installation failure and the lawsuits / forced re-building that can result. Additionally, the combination of Green Glue and resilient channel saves valuable space and money relative to other options, such as sound clips or double stud walls.
Moving beyond this synergy with resilient channel, and taking a look at STC (ignoring low frequency considerations), one finds that there are some applications where Green Glue is an ideal choice, and some applications where it is not the best choice for meeting these requirements. Green Glue has been fire tested and demonstrated to be compatible with all fire-rated constructions. So, the inclusion of Green Glue does not affect the fire rating of an assembly. Contact The Green Glue Company for an idea of where Green Glue is ideal, and where it isn’t, for your STC-based applications. Another extensive round of lab tests is scheduled for March of this year, where short-circuit immunity in resilient channel assemblies will be further explored.
The Basic Principles Involved.
Rather than looking blindly at STC ratings, this section of our site will look at overall wall performance. And, what better place to start than with some discussion of the 5 Basic Principles of Sound Isolation - the 5 things that can help your walls stop more sound. From there we’ll look at the The 4 basic ways to improve the performance of a wall - What areas of improvement available to you.
Green Glue as a stand alone product
More and more acoustical consultants are concerning themselves with actual wall performance more than STC. More and more, they are looking at transmission loss data that includes low-frequency data. The Green Glue Company has more same-lab full-frequency-range data (including comparative data) than any other company we are aware of, and Green Glue yields impressive low frequency benefits in many constructions. Read: Third Party Testing Results
These documents may also be of aid:
3. The Sound Absorption Properties of Walls
4. Wall Types - There are three different wall types you can use to build high performing walls.
5. Lab Testing and Results - Independent Third Party Transmission Loss Reports