Sound Insulation vs. Regular Insulation

When deciding on the best product to use for my soundproofing project, I researched the benefits of sound insulation vs. regular insulation. If you’ve wondered the same, here’s a quick answer:

The differences between sound insulation vs. regular insulation are obvious. Regular insulation is for thermal insulation, whereas sound insulation is for acoustic insulation. Regular insulation is usually made from cellulose, fiberglass, or rockwool, while acoustic insulation will include MLV.

Also read: Best Insulation Materials for Soundproofing And Acoustics

Sound Insulation vs. Regular Insulation

In this article, I’ll cover the key differences between regular insulation and sound insulation. Hopefully, by the end, you’ll understand why it’s much more beneficial to use dedicated sound insulation in your next project.

What’s the Difference Between Sound Insulation and Regular Insulation?

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At the most basic level, all insulation does the same thing: it insulates. But what it’s designed to insulate against will change some of its properties.

Also, it’s worth noting now that, for the most part, thermal and acoustic insulation share many of the same properties. Both forms of energy are effectively absorbed by loose yet dense materials.

But the key difference is that sound insulation needs to work against vibrational energy rather than heat energy. Sound waves are a form of mechanical energy, and this requires slightly different insulation characteristics.

Because of the shared properties, both kinds of insulation will restrict other types of energy to an extent. For example, sound insulation will restrict heat transfer to a degree, but not as effectively as regular insulation.

Another key difference is that sound insulation needs more mass than thermal insulation. Sound can be blocked, absorbed, or reflected. Either blocking or absorbing sound waves are considered forms of soundproofing.

Adding mass through insulation is a way of blocking sound waves from transferring through a structure. More mass simply means it’s harder for sound waves to make a structure vibrate, meaning they don’t travel as far.

Something like fiberglass insulation (Amazon link) generally doesn’t have enough mass to block sound waves.

Its open structure will help to absorb sound waves, but this isn’t necessarily the result you want from sound insulation; blocking is more important.

Fiberglass insulation will usually only absorb high-frequency wavelengths. While this is better than nothing, dedicated sound insulation will usually be able to tackle high- and mid-frequency wavelengths.

Of course, it’s worth noting that sound insulation alone won’t be give amazing results. There are more effective ways to add mass to a structure, such as mass loaded vinyl (Amazon link).

However, when used alongside a range of other soundproofing materials, sound insulation will always be a better choice than regular insulation. In a pinch, though, regular insulation will be better than nothing.

Comparing Sound Insulation vs. Regular Insulation

While acoustic insulation is the obvious choice for a soundproofing project, it’s worth thinking about a specific comparison between the 2 products in order to understand why.

To make this easier, I’ve put together a comparison chart.

 Sound insulationRegular insulation
MaterialMineral wool or foam with MLV or drywallFiberglass or cellulose
PriceMid to highLow to mid
AvailabilityLess commonWidely available
Ease of useEasyEasy
DensityHigh (at least 45kg/m3)Medium to low (between 12 and 48kg/m3
STCAround 50Around 36

As can be expected, sound insulation wins for density and STC. STC stands for sound transmission class, and is the measurement of how well a material isolates sound waves.

Acoustic insulation is better for a number of reasons. Importantly, it’s made with denser materials. This increases mass and is more effective at reducing sound transfer.

In part, this is thanks to the outer layers of mass loaded vinyl you’ll usually find on acoustic insulation. For example, if it comes in the form of panels, it’ll be a foam core with MLV on each side, and maybe even a sheet of drywall.

Other kinds of acoustic insulation will simply come in sheets, much like mineral wool insulation. These will still do a good job, but won’t be as effective as the types with mass-rich materials.

However, regular insulation does move ahead when we look at availability and price. This is simply because it’s a more widely used product, meaning there’s a greater range of options to suit all budgets.

You’ll easily find regular fiberglass or cellulose insulation in DIY stores and online.

Acoustic insulation, however, will take a bit more hunting. You might only find it available directly from the manufacturers. However, there’s plenty of choices if you look hard enough.

Often you’ll find products like mineral wool insulation (Amazon link) offered as acoustic insulation.

It’s not dedicated soundproof insulation but is more effective than fiberglass, simply because it’s denser.

In fact, if you can’t find any specific acoustic insulation, I recommend using mineral wool. Out of the types of regular insulation, it’s definitely the best.

I’d always go for a proper acoustic insulation product if you’re able to find one though. The results are much better than using regular insulation.

How to Make DIY Acoustic Insulation

How to Make DIY Acoustic Insulation

As I’ve mentioned, you might find it difficult to find a cost-effective acoustic insulation product.

However, it’s not particularly difficult to make your own. Here’s a guide on how to make your own acoustic insulation.

For this, you’ll need the following materials:

  • Drywall sheets
  • Mass loaded vinyl
  • Closed cell foam sheets
  • Green Glue
  • Vinyl cement or glue
  • Staples

Ideally, you’ll want the thickest drywall you can find. Half-inch is the most common type, but if you can find something like 5/8 inch, use that.

Instead of closed cell foam, you could use sound deadening mats. These are dense rubber sheets designed to deaden sounds, usually in a vehicle.

The only reason I didn’t suggest them as the main product is because most have foil backing. This makes them quite difficult to stick to other materials.

Generally, closed-cell foam will be fine for this job because it’s used to deaden sound waves and isn’t there to add mass.

Here’s the method.

1. Measure your materials

The easiest way to make acoustic insulation panels is to use a sheet of drywall as your base.

You’ll probably have 4’ x 8’ sheets of drywall, so this is your starting point. Of course, if you need smaller panels, cut them to size first.

You should measure out your mass loaded vinyl and foam to the right size before you start sticking.

MLV will either come in small sheets or a larger roll. Either is fine, but the sheets might be slightly easier to work with on this project.

2. Start assembly

Flip the drywall over so you’re working on the rear side. Apply a good layer of Green Glue using 2 tubes.

This will begin to cure within 15 minutes, but be aware it’s not glue. Therefore, you’ll have to stick the next layer down with actual glue, or staples.

Apply a layer of MLV over the Green Glue. As mentioned, fix this in place with staples or glue. It’ll be worth waiting for these layers to dry before moving on, which should take 24-48 hours.

3. Add the next layer

Next comes a layer of closed cell foam. Something like neoprene is fine; although the thicker the foam is the better it’ll be for this job.

Apply a generous layer of vinyl cement to the MLV and stick the foam over the top.

It’s probably worth applying some pressure to the layers while they dry so you get a good bond. Put a weight on it and leave it to dry again.

4. Add the final layer

Finally, you need to apply another layer of MLV to the back of the foam. This is an easy way to add more mass to the insulation panel.

Again, add a generous layer of glue, stick it down, and apply a weight. Everything should be dry in 48 hours.

That’s pretty much it. The result should be a relatively heavy, high mass sheet of drywall that’ll effectively dampen sound waves and insulate against unwanted noise.

The benefit of building it on a sheet of drywall is that it’s modular, meaning you can scale production up as much as you need to.

While this might seem like quite a bit of work, the results will be much greater than simply using a layer of regular insulation.

Of course, if you don’t have the means to build sheets of insulation, regular insulation will still do something. It’ll definitely be easier to use if you’re insulating wall cavities.

I recommend choosing the densest type of regular insulation available, which is something like mineral wool. Adding this into a wall cavity will help to reduce noise transfer to an extent.

Some Final Thoughts

I hope this article has highlighted the difference between sound insulation vs. regular insulation.

Acoustic insulation is always going to be the better option for soundproofing but is let down by its lesser availability. If this is the case for you, regular insulation won’t be the worst option.

I recommend seeing what you can do with your budget and even considering making your own if you can.

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