Polystyrene insulation as a sound insulation.

[PhilE]

Hey guys,

Does anyone know about the properties of this stuff? I had a builder round today talking over the plans for my mix room modifications and he suggested a sheet of polystyrene insulation, instead of a stud wall filled with Rockwool, infront of the window. He predicts a better result... but I/m not sure I believe him! Seems too good to be true.

[kurt]

Not true. Hi is talking about heat.

[PhilE]

Yeah- he was talking about sound but I got the impression that it was something he'd not had to consider too much.
So what IS the best way to stop sound getting in and out- I don't have a lot of space to use up with layers.
P.S. this room is ONLY for mixing- no instrument recording ever happens in here so levels don't get over about 90dB and are usually around 80-85.

[parloursound]

Don't do it, it the worst thing you can do. you would be better putting nothing in there. There is a reason people have been using rockwool for years - don't try to reinvent the wheel.

[Bob Ross]

FWIW, my dad, who was in the plastics industry for 20+ years (sales & marketing, not engineering, so you should take this with a big grain of salt) insists that closed-cell expanded polystyrene foam insulation -- the stuff that (often incorrectly) gets referred to as Styrofoam® -- does exhibit some soundproofing properties when used as the middle layer in a sandwich between sheetrock and/or plywood leaves.

He suspects that due to the the irregular, non-uniform shape of the expanded plastic beads, as well as perhaps the compliant nature of the material, sound transmission is impeded through the EPS board.

I can think of plenty of reasons why it would be preferable to use RockWool (or the equivalent) rather than EPS...but I guess I can also see how EPS could fulfill certain requirements both acoustical and environmental.

It's definitely *not* commonly used for its sonic properties.

[TEMAS]

Originally Posted by PhilE

I had a builder round today talking over the plans for my mix room modifications

Builders will do and say anything to try and get you to agree to do it the way thats easiest for them. I had to supervise every single nut, bolt and screw of my build.

[PhilE]

Originally Posted by TEMAS

Builders will do and say anything to try and get you to agree to do it the way thats easiest for them. I had to supervise every single nut, bolt and screw of my build.

In a way this is why I checked- This guy is happy to do my rockwool work at the back and sides of the room but he didn't feel it was necessary for the front and roof (where the acoustic is less concern than leeking)

Originally Posted by parloursound

Don't do it, it the worst thing you can do. you would be better putting nothing in there. There is a reason people have been using rockwool for years - don't try to reinvent the wheel.

Yeah- I was very happy with the rockwool plan until this easier option came to light!

I'm going to have a rethink!

[Kiwiburger]

Polystyrene foam is used underneath MDF or flooring to reduce impact. However - the resonant frequency is in the audio range (the stuff 'squeaks') so this is dangerous - I prefer open cell rubber foam.

The stuff is a major fire hazard.

As soundproofing, it's low mass is useless. It isn't absorbant, so it's useless for sound treatment.

Basically useless. It's cheap and crushable - that's why it's used for packaging.

[PhilE]

I guess we're not all talking about the same thing seeing as he's talking about a building material not a packing material... either way- Its made me think about a redisign and I 'm on the verge of something better (if a little more expensive!) as a result!

[lordmiguel]

mass stops sound.

especially with low frequencies.

i would imagine the styrene would act more like a glorified air barrier.

probabaly works ok with highs and mids though.

[Kiwiburger]

I guess we're not all talking about the same thing

oh yes we are. The building material is expanded polystyrene foam, just as equally useless as the expanded polystyrene foam packing material.

If somebody tried to build me a house out of the cheap shit I would be disgusted. It's a fire trap. The reason it's a good thermal insulator is because it's basically air bubbles covered in plastic.

[rockstar_josh]

Yeah, it needs to be more dense than that. I'm using a material called Celotex soundboard, it's supposed to have good sound reduction. Not sure how good it is yet, I'm stll building.

[PhilE]

Originally Posted by rockstar_josh

Yeah, it needs to be more dense than that. I'm using a material called Celotex soundboard, it's supposed to have good sound reduction. Not sure how good it is yet, I'm stll building.

I'm going back to the original Rockwool idea but with a different room configuration so as I can afford more space... will mean starting the acoustic treatment from scratch (repositioning what is there at the moment and adding to it) but in the long run will be worth it as I dont like the sound leakage through that end wall.
I've been working in this room for over a year now and noone has ever complained but now I am not moving rooms as soon as I'd originally thought I want to really feel happy at the console.

[Reza]

If you're looking to sound proof as opposed to absorb freqs, then the following's worked really well for me in soundproofing a window.

I built a frame out of 2x4's, then insulated with 3 layers of 1/2" homosote (the stuff school notice boards are made out of, available at any big hardware store). Then covered that with three layers of 5/8" thick drywall, with the edges of the drywall fully caulked at each layer. That's how I built the two doors for the room as well - with thin sheets of ply either side to hold it all together. The drywall comes closest to giving the same push as the brick walls of the room, which balances the space.

Then you just treat the room as per usual - tri traps in the corners, broad band absorbers at first reflections (including clouds for the ceiling), and diffusion on the back wall.

That's what I'm currently implementing in my space anyways.

Hope it helps.

Cheers - Rez

[TEMAS]

Originally Posted by PhilE

In a way this is why I checked- This guy is happy to do my rockwool work at the back and sides of the room but he didn't feel it was necessary for the front and roof (where the acoustic is less concern than leeking)

Without seeing details of the room, I can't comment on whether the front and roof should be treated as substantially. If there's a room above, or even to the side that you're trying to isolate yourself from, I'd recommend treating the roof the same as the walls. If you're building a room within a room, it will only ever be as good as the weakest link.

In the UK, I'd recommend Rocksil. They do various densities; I did my room using RS-45 and RS-60, the latter being the more dense option. Encon was the cheapest place to get it.

Oh, and don't under-estimate how much sound travels along and through surfaces. If I could do it all over again, I'd spend way more time looking into ways to isolatie vibrations that come in from outside (i.e, footsteps above and the people nextdoor) as well as those created inside the studio, (i.e a drummer) .

Hope this helps.

[PhilE]

Originally Posted by TEMAS

Without seeing details of the room, I can't comment on whether the front and roof should be treated as substantially. If there's a room above, or even to the side that you're trying to isolate yourself from, I'd recommend treating the roof the same as the walls. If you're building a room within a room, it will only ever be as good as the weakest link.

In the UK, I'd recommend Rocksil. They do various densities; I did my room using RS-45 and RS-60, the latter being the more dense option. Encon was the cheapest place to get it.

Oh, and don't under-estimate how much sound travels along and through surfaces. If I could do it all over again, I'd spend way more time looking into ways to isolatie vibrations that come in from outside (i.e, footsteps above and the people nextdoor) as well as those created inside the studio, (i.e a drummer) .

Hope this helps.

Thanks for the input- I'll check Rocksil out. I have been working in the room for over a year as I mentioned its just that it started out as a temp room after I moved out of my old studio because I was sharing the space and it was too hard to get into my own room! I had another space lined up but then it's so nice being set up at home with fewer overheads I decided to stay put and make the space a bit more pro! There is nothing to the side of me as such and although the sitting room is above it's not too bad... I mix at moderate levels.

[Eric Desart]

Originally Posted by Bob Ross

FWIW, my dad, who was in the plastics industry for 20+ years (sales & marketing, not engineering, so you should take this with a big grain of salt) insists that closed-cell expanded polystyrene foam insulation -- the stuff that (often incorrectly) gets referred to as Styrofoam® -- does exhibit some soundproofing properties when used as the middle layer in a sandwich between sheetrock and/or plywood leaves.

When one uses polystyrene in a cavity as partly filling you will DEGRADE the acoustic TL properties of that wall.
Since closed cell it will decrease the air cavity making that air spring stiffer thereby increasing MSM which not only influences the frequency of the resonant frequency in itself but the whole subsequent TL curve, which is related to that resonance frequency.

From that point of view your dad is right: it does exhibit some soundproofing properties: it makes that wall significantly worse (even when compared with an empty cavity).

If you make it into a glued/bonded sandwich panel, it acoustically starts behaving quite different and is not related to traditional drywall discussions here.

[Sigma]

Originally Posted by Kiwiburger

Polystyrene foam is used underneath MDF or flooring to reduce impact. However - the resonant frequency is in the audio range (the stuff 'squeaks') so this is dangerous - I prefer open cell rubber foam.

The stuff is a major fire hazard.

As soundproofing, it's low mass is useless. It isn't absorbant, so it's useless for sound treatment.

Basically useless. It's cheap and crushable - that's why it's used for packaging.

and puts out toxic poisons when ignited..it's not class A fire rated for commercial applications..all my studios stuff is commercial class A even though it's a "home" studio