Acoustic insulation is a go-to choice to soundproof your home, but should it also be for insulation? To know, you should probably check its R-value.
Acoustic insulation has an R-value, which measures insulation ability or how well it can resist heat flow. However, this may vary according to material and is expected to be lower compared to thermal insulation. To measure soundproofing quality, it is better to use STC or Rw.
Keep reading this article if you want to know how acoustic insulation can have an R-value or what values should be used to indicate soundproofing quality. We will also discuss the difference between thermal insulation and acoustic insulation.
How Does Acoustic Insulation Have an R-Value?
R-values are often used for thermal insulation among buildings, so how does this relate to acoustic insulation? First off, we need to understand what an R-value is.
What Is an R-Value?
R-value is a measure of thermal or heat flow resistance. Typically, heat would flow from hot to cold. To disrupt this, insulation is used, which slows down the transfer of heat. Thus, R-value is also an indication of how well the insulation can disturb the flow.
Insulation can delay heat flow by being a barrier in the usual path of heat. For instance, typically, the heat inside your home would escape to the colder outside during the winter. However, if your home is insulated, it is harder for heat to go out. Thus, it gets trapped inside.
Acoustic Insulation and R-Value
Sound is insulated when its vibrations find it hard to permeate through surfaces. This is done by making use of heavy and dense materials.
Sometimes, the design of the acoustic insulation may also make it difficult for heat to dissipate. Thus, to some extent, it can disrupt heat flow and have an R-value.
However, acoustic insulation is often designed to be denser than most thermal insulators. Hence, its ability to disrupt heat flow may not be at par. Some acoustic insulation may even have an R-value of zero.
What Are Common R-Values for Acoustic Insulation?
R-values depend on the material used for insulation. Common materials used for acoustic insulation include fiberglass and rock wool.
- Rockwool. Rock Wool Batt has an R-value of 3.14 R/Inch – 4.00 R/Inch. Meanwhile, Rock Wool Blown has an R-value of 3.10 – 4.00.
- Fiberglass. Fiberglass Batts have an R-value of 3.14 R/Inch – 4.30 R/Inch, which may vary depending on thickness and density. Fiberglass Blown has an R-value from 2.20 R/Inch – 4.30 R/Inch, depending on whether it is for the attic or the wall.
Higher R-values mean better insulation.
How Is R-Value for Acoustic Insulation Calculated?
The R-values commonly shown for materials are a combination of its down R-value and up R-value.
The down R-value indicates how well it can keep heat out, while the up R-value measures how well it can keep heat inside. These two are added together for an overall rating.
What Is More Appropriate Value for Acoustic Insulation?
Acoustic insulation is primarily for sound insulation or reducing sound permeation. To know how well your acoustic insulation is doing at its job, it is better to turn to other value systems rather than R-values.
STC and Rw are good indicators of your acoustic installation’s soundproofing ability.
What Is STC?
Sound Transmission Class (STC) is a measurement of sound isolation. It indicates how well it can keep sounds within a room, thereby preventing them from crossing onto another area.
Higher STC ratings mean better sound isolation abilities. These ratings are calculated by generating a curve of transmission loss values within 125 Hz to 4000 Hz. Transmission loss is a difference in decibels or sounds between two areas. The generated curve will then be compared with standard curves to determine the STC rating.
STC is often used in the United States. A downside of this value system is that it is not an adequate measure of how well low-frequency sounds are isolated since the frequency range does not cover them.
What Is Rw?
Weighted Sound Reduction Index (Rw) is another way to measure sound isolation. Globally, it is used more often than STC.
Compared to STC, Rw also covers a more extensive frequency range. Hence, it can be used to assess how well low-frequency sounds are isolated.
Also, RTC is expressed in decibels, unlike STC, which is a rating compared to standard curves. Thus, there is no straightforward formula to convert between the two.
Acoustic Insulation vs. Thermal Insulation
As I have mentioned above, acoustic insulation is not that good at preventing heat flow. Thus, it has lower R-values. But what insulation should you use if your main goal is to control heat transfer?
Thermal insulation is primarily intended to disrupt heat flow by either slowing it down or reducing radiant heat gain. The former method is applicable for convective or conductive heat flow. It delays the flow of heat from one object to another or heat in circulation through liquids or gases.
Meanwhile, reducing radiant heat gain is applicable when you want to insulate against the heat traveling in a straight path and warms everything ahead. An example of this would be the sun’s rays.
To reduce radiant heat gain, you can reflect heat to re-emit it. Have you ever heard of the iconic white houses of Santorini? The white color reflects heat; thus, cooling them and reducing radiant heat gain.
Common Thermal Insulation Materials
Thermal Insulation materials differ from acoustic insulation in that they are less dense than the latter.
Examples of common thermal insulators are:
- Mineral wool
- Foam boards
R-values may vary depending on material and thickness. Reflective materials, like foils, do not have R-values.
Acoustic insulation is primarily for sound and not for heat. Hence, while it may have R-values, they may not be the best for regulating heat flow.
Weigh out if your priority is regulating heat or soundproofing to know which insulation is better for you. Also, meet the insulation requirements your country or state may have.