The Limitations of Isolation Products
Back to Full ListIf only it were that simple: a 1/16” thick mystery material that could achieve IIC ratings in the low 70s, no matter the construction. Imagine being able to tell customers to install this miracle product that adds virtually no height to a floor, yet somehow delivers performance comparable to several inches of rubber underlayment or a ceiling suspended two feet below the structure. Or that a thin foam strip applied to studs and joists could dramatically reduce both airborne and impact noise. Life, and soundproofing, would be easy and quiet for everyone.
Unfortunately, physics doesn’t bend to marketing. Some manufacturers and distributors would have you believe otherwise, but the fundamental laws of acoustics and the way materials interact prevent these “wonder products” from delivering the results they claim.
We frequently hear from customers who were misled, sometimes by well-known competitors, into purchasing the wrong products, or simply too many of them. In one example, a respected company promotes wall and ceiling assemblies with STC and IIC ratings in the 70s, using fairly basic materials combined in ways that were never tested together. Their claims assume that the performance gains of each product simply add together: Product A improves STC by 15 points, Product B by 10 points, so together they must improve by 25 points.
That’s not how it works.
Sound isolation performance doesn’t increase linearly. It’s a logarithmic relationship, meaning results diminish as layers are added. Combining materials doesn’t necessarily multiply results, in many cases, performance maxes out at the gain from the strongest component, or improves only marginally (2–3 points at best).
The Reality Of How It Does Work
The truth is simple: without significant decoupling of a wall or ceiling, achieving very high levels of sound isolation is extremely difficult and often impossible. There are rare exceptions, such as a multi-foot-thick concrete wall, but if that’s your situation, you likely wouldn’t be reading this.
To understand these principles more deeply, including why certain materials and assemblies work while others don’t, we recommend reviewing the following IsoStore research articles:
Basic Sound Isolation Concepts
Comparing Types of Sound Ratings
Maximizing Rubber Underlayment Performance
Choosing Your Sound Door Wisely
And if you are still confused about the limitations of soundproofing, drop us a line. We are happy to help dispel any untruths pushed around the web on various competitor's sites, YouTube videos from 'experts', or forums.