Acoustiblok is a U.L. Classified (UL # CLBV.R21490), viscoelastic polymer that comes in two forms:
- Blok16 – 1/8th” thick sheet with a weight of 1 pound per square foot.
- Blok32 – 1/4″ thick sheet with a weight of 2 pounds per square foot.
Both are made from recycled plastics and non-toxic minerals that are mixed and pressed into a membrane sheet.
These sheets are then trimmed to a standard size of 54” wide x 30’ long and rolled up for easy transportation. The rolls weigh roughly 135 pounds each at this size. Longer rolls ranging from 60’ long (at 270 lbs.), to 350’ long (at 1,575 lbs can also be manufactured.
Sound Transmission Classification
The Sound Transmission Class is a single number method of rating how well wall partitions reduce sound transmission. The STC provides a standardized way to compare products such as doors and windows made by competing manufacturers. A higher number indicates more effective sound insulation than a lower number. Acoustiblok will generally raise the sound transmission index.
Mass is important for sound isolation. Acoustiblok ranges from 1 pound to 2 pounds per square foot. That’s a lot of mass for a material that is between 1/8” to 1/4” thick! But mass is not the only thing needed to lower sound across a wide spectrum of frequencies.
Offsetting Diminishing Returns
An increase of about 5 STC is typical for each doubling of surface weight. This is a great result for the initial doubling, but the cost of each additional doubling offsets the gains in STC due to the law of diminishing returns.
Due to these diminishing returns, the best way to achieve high levels of sound isolation is to build a heavy, limp, and airtight assembly. If the mass of the assemblies increases while decreasing their stiffness, you will see significant gains in Transmission Loss as a result. This is due to bending-wave coincidence, where a flexible or resilient material can result in a coincidental gain in TL of more than 15dB at specific frequencies.
Sound proofing materials do not need to be super heavy if it means they must also be super stiff and rigid.
It is noteworthy that sound travels efficiently through dense solids. And every type of sound can excite your boundaries, causing them to resonate at different frequencies. As a result of this, you should know the frequency spectrum of your offending noise before any attempt to design and build an enhanced boundary.