Acoustic Foam vs Rockwool: 5 Things to Know Before Buying!


You’re probably thinking about using one of these products to soundproof a wall or a door. But you’re not sure which one is better. Here’s what you need to know:

Rockwool is better for soundproofing and thermal insulation because of higher density and weight. It can be installed inside a wall or directly on the surface. Acoustic foam panels are designed for surface-application only. Those with grooves or wedges are better at reducing echo and improving acoustics. 

That’s a quick, short answer, but let’s not leave it at that. There’s other, just as important information to consider:

1. Soundproofing

If you want to block some serious noise, rockwool batts (see on Amazon) are definitely the superior option. Rockwool can block lower frequencies (think of bass) and vibrations. To be more specific, it can block sound frequencies lower than 1kHz. Acoustic foam can only block mid-to-high frequencies and even then the density and heaviness of the panel plays a big role.

Rockwool batts/panels are typically placed between studs, to cover all that empty, hollow space in the wall. So if you’re renovating or building a wall from scratch, opt for rockwool batts to get sound and thermal insulation benefits. Having said that, rockwool can be placed on the surface as well.

Acoustic foam on the other hand is installed on the surface to reduce echo because it’s soft, so the sound doesn’t bounce off of it as much. It is a lightweight material made from polyurethane foam from either polyether or polyester. Because it’s light weight and not really dense (the two features come hand-in-hand), they’re not as good when it comes to soundproofing.

2. Echo Reduction

If you want to improve acoustics, acoustic foam is the go-to option. It’s easier to install (we’ll talk about that in a moment), weighs less and it’s usually more effective for echo reduction than rockwool is. There are many designs, colors and sizes to choose from as well. Get the ones with wedges because they are better suited for this purpose.

Rockwool can also provide echo reduction, so if you need to reduce noise AND reduce echo, rockwool is the better option. Fiberglass is great too. But if you need to only reduce echo in order to improve acoustics, go with acoustic foam panels.

3. Installation

Acoustic foam is a lot easier to install on a surface. All you need to do is use some hanging strips or glue and stick it onto the wall, door or any other object you have in mind.

With rockwool the situation is a bit more tiresome, because rockwool batts emit small particles which get in the air and can irritate skin, eyes and lungs. For this reason, you should wear goggles and gloves when working with rockwool.

If you decide to hang a rockwool panel on a visible surface, make sure to cover it with a dense fabric first, so that the irritating particles can’t escape out in the open. With the rockwool inside the fabric, you can install it like any other acoustic foam panel, with hanging strips, glue or a different hanging method.

Also, both products can be cut down with a knife to the desired size.

4. Fire Safety

Rockwool insulation won’t burn, or release toxic gases or smoke when exposed to high heat. It in fact helps delay the spread of fire, which is why it’s commonly used in construction.

Acoustic foam varies in this regard. There is fire retardant acoustic foam which is totally non-flammable. It can be used in the same way as ordinary acoustic foam but is far more versatile. It is of particular use in heating and ventilation ducts, machinery guards and enclosures and even buildings.

Now, does that mean that your panels should 100% be fire-resistant if you’re installing them on a surface? Not necessarily, many people buy the cheapest acoustic foam or even use egg crates to reduce echo, which are definitely a fire vulnerability. Also, you probably already have a ton of books, curtains and similar objects laying around and just waiting to get caught on fire. B

Overall, it’s good to keep this in mind – rockwool can be exposed to high heat, but with acoustic foam it depends on the specific product since some are fire retardant and others are not.

5. Price & Availability

Rockwool is a very basic material and the cost doesn’t vary much regardless of where you buy it (unless there’s a discount available of course).

With acoustic foam you have a much wider selection, thickness, fire-retardant properties (or lack of), and you can indulge in slick and fancy designs or opt for simpler and more affordable ones that reduce echo all the same.

Both of these sound insulation products are widely available. For the best prices and frequent discounts, I usually recommend getting them on Amazon. I also shared my top 6 effective soundproofing panels that can be installed directly on a surface. So definitely check it out before you go.

Talk to you soon! 

Luka Baron

Soundproof expert and a staunch opponent of noise. This website is a free source of information on how to 'keep it down a notch'. I update the content regularly to keep up with advancements in the soundproofing industry.

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