I regularly take questions on my YouTube channel from people about home soundproofing tips – this week Jake from Kansas asked me whether or not I believed fibreglass insulation was good for soundproofing or not.

The easy answer is yes… and no.

Hmmm… probably not the clear-cut answer that you were looking for so let me explain in more detail.

Does Fibreglass Insulation Absorb Sound?

Yes. And in fact, this is what it is best used for when soundproofing. It absorbs, rather than blocks noise.

Fiberglass is commonly used in corporate buildings, for example in private office blocks where the builder has tried to block sound between offices.

I won’t lie. There is some benefit to this.

Typically, you might expect to get around 3 to 5 decibels in sound and noise reduction as the fibreglass insulation will absorb some of the sound.

What it won’t do is completely block sound from coming into a room or building if it only a few inches thick.

If you want to use fiberglass to completely block sound and soundproof a room then you would probably need to install a 4-foot deep insulation of fibreglass – which as you can imagine is completely impractical – especially if it’s something you want to do at home.

A far easier solution would be to use sound blocking panels, such as gypsum board on the walls and ceilings, plus an additional layer of drywalling. I have gone into a little detail on how to do this with my guide to soundproofing a home office.

Fibreglass insulation will also act as a great heat insulator, so I do recommend using it with home soundproofing projects.

You will notice that on various guides on my website, I do advise the use of fibreglass insulation. So why do I recommend it based on the observation above.

Well, it’s all done to the sound absorbing qualities.

When you are in a room, a lot of the loud noise you hear will be reverb and echo inside of the room.

If you can reduce echo by absorbing it, then to your human ear, the noise levels in the room will be cut – which is all part of soundproofing.

But, I don’t advise simply using fibreglass insulation for soundproofing – it needs to be just one element of your overall project.