Sound Insulation

[Arthur Marshall]

Is the kind of expanding polystyrene you can squirt out of a tube any good for sound insulation? I've got a cruiser stern over an aircooled Lister SR2 and am getting deafer by the minute. I'm just in the process of making new deck boards over the engine and thought I might try the polystyrene rather than proper sound insulation stuff, mostly on the grounds of being broke.

[station tug]

go scrap yard and get some sound insulation off a bonnet

[Tony Brooks]

or from under the front carpets on a diesel car.

[Phil Ambrose]

I had a Broads type dayboat at one time with an inboard 2 pot Stuart Turner diesel which sat amidship under what was basically a box.

I glued egg trays to the inner surfaces, this hushed it up a bit and was just about free.

Phil

[Grace and Favour]

Is the kind of expanding polystyrene you can squirt out of a tube any good for sound insulation?

You may find it melts/collapses if it gets too warm

[Arthur Marshall]

Thanks all - I suppose I'll have to go for the real stuff again!

[trackman]

You really need mass and sound absorbency. Egg boxes might give the latter but not the former.

The mass damps down vibrations of the barrier itself, reducing that form of noise transmission, the absorbency deals with airborne noise. With only one of these you wont get a fully effective outcome.

This is why purpose made materials have a foam or felt backed by a sheet of lead or other dense material.

Closed cell foam, the form of many polystyrene sheets, isn't even particularly absorbent. You need open structured material for that.

[Arthur Marshall]

Did a bit more research and found one article hat said that using polystyrene foam might even make the situation worse. hey ho.

[Machpoint005]

Is the kind of expanding polystyrene you can squirt out of a tube any good for sound insulation? I've got a cruiser stern over an aircooled Lister SR2 and am getting deafer by the minute. I'm just in the process of making new deck boards over the engine and thought I might try the polystyrene rather than proper sound insulation stuff, mostly on the grounds of being broke.

No, it isn't any good. That's my professional opinion.It also makes a mess.

I had a Broads type dayboat at one time with an inboard 2 pot Stuart Turner diesel which sat amidship under what was basically a box.

I glued egg trays to the inner surfaces, this hushed it up a bit and was just about free.

Phil

Not recommended. Oil spray on cardboard is a serious fire risk.

[Neil2]

Is the kind of expanding polystyrene you can squirt out of a tube any good for sound insulation? I've got a cruiser stern over an aircooled Lister SR2 and am getting deafer by the minute. I'm just in the process of making new deck boards over the engine and thought I might try the polystyrene rather than proper sound insulation stuff, mostly on the grounds of being broke.

The answer is no.

 

For true sound insulation you need mass. It doesn't really matter what you use, but dense material such as lead works pretty well.without taking up a lot of space, which is why lead lining is the first choice for soundproofing. You can get lead sandwich soundproofing boards but they are quite expensive.

 

Even if you went for aluminium deck boards rather than plywood it would make a big difference but again it is probably going to be more expensive.

 

One thing you can do on the cheap is put bricks or concrete blocks in the engine room. But with a heavy Lister you would have to be careful not to upset the trim of the boat too much.

[RubyTuesday]

There is a Vinyl Matt material that has a denity approaching that of lead, it is far easier to work with and has the benefit of also having a damping effect on the substrate that you fix it to. Doors built with it as aligning compared to doors built with a lead lining end up with a better acoustic performance. You can buy it from siderise. They are very helpful. They also make a lot of those composit engine bay lining materials that other companies rebrand.

The main material is BM0050 also known as "Sheet Block"

 

The other important rule is to make sure that you make a space as airtight as possible. Of course in an air cooled engine bay this is harder to archive... but careful baffling of enlarged ventilation ducting can be highly effective and make sure that the deck boards sit on rubber seals.

 

If you want to diy then a combination of Rockwool RW3 (don't let anyone fob you off with RW45) on the sides of the engine bay in a wooden frame with BM0050 nailed and glued over it will work well. You could also fix this to the under with of the deck boards.

[Robbo]

The answer is no.

 

For true sound insulation you need mass. It doesn't really matter what you use, but dense material such as lead works pretty well.without taking up a lot of space, which is why lead lining is the first choice for soundproofing. You can get lead sandwich soundproofing boards but they are quite expensive.

 

 

You also need something to absorb the sound as well, if it's just hard material the sound just get's bounced around.

[Machpoint005]

Rockwool RW45 is now ProRox SL 920.

RW3 is now ProRox SL 930.

The only difference is the density: 45 kg/m3 and 60 kg/m3 respectively. That makes very little difference in terms of the acoustic absorption coefficients but the heavier slab is slightly stiffer and can support its own weight rather better.

[Neil2]

It's easy to get confused between sound absorption and soundproofing.

 

If you are trying to reduce noise within a room you will need materials to absorb the sound, to prevent it reverberating. Many of the materials referred to are for this purpose.

 

Sound absorption is very important if you are trying to deaden the sound within an enclosed space, such as a boat cockpit or the saloon of a car.

 

But sound absorption materials will do very little to reduce the sound level and/or stop sound transmission to the outside.

 

On the typical narrowboat, sound absorption is no use because you are not in the same space as the noise, what you need to do is reduce noise transmission.

 

You can only reduce sound transmission by space, mass or by dampening vibrations, and it's well worth considering the latter.

 

I think on narrowboats it is often undersold how much noise can be reduced by flexible transmission systems, and I mean true u/j types. I have a boat with Aquadrive and I couldn't believe how little noise there is from the engine room compared to my last boat. The problem is, as you reduce one sound source the others seem to become more prominent, and in my case I now find the exhaust note intrusive. I guess I will fit a hospital silencer then the noise of the prop will start to annoy me.

[blackrose]

Is the kind of expanding polystyrene you can squirt out of a tube any good for sound insulation?

 

I don't know. I thought expanding foam from a can was generally polyurethane, not polystyrene?

 

Anyway, as others have said, it's light, open-cell foams for sound attenuation/absorption and isolated dense materials to prevent sound transmission. You can isolate the dense materials by "floating" them on rubber mounts stuck on with silicone.

Edited February 19, 2014 by blackrose

[RubyTuesday]

It's easy to get confused between sound absorption and soundproofing.

 

If you are trying to reduce noise within a room you will need materials to absorb the sound, to prevent it reverberating. Many of the materials referred to are for this purpose.

 

Sound absorption is very important if you are trying to deaden the sound within an enclosed space, such as a boat cockpit or the saloon of a car.

 

But sound absorption materials will do very little to reduce the sound level and/or stop sound transmission to the outside.

 

On the typical narrowboat, sound absorption is no use because you are not in the same space as the noise, what you need to do is reduce noise transmission.

 

You can only reduce sound transmission by space, mass or by dampening vibrations, and it's well worth considering the latter.

 

I think on narrowboats it is often undersold how much noise can be reduced by flexible transmission systems, and I mean true u/j types. I have a boat with Aquadrive and I couldn't believe how little noise there is from the engine room compared to my last boat. The problem is, as you reduce one sound source the others seem to become more prominent, and in my case I now find the exhaust note intrusive. I guess I will fit a hospital silencer then the noise of the prop will start to annoy me.

Yes except the use of "sound absorption" materials is paramount in the construction of a "soundproof" wall. For example compare a stud partition wall of:

plaster board : air space (2x4 timber) : plaster board

Compared to

Plaster board : rockwool RW3 (2x4 timber) : plaster board

 

The higher density of rockwool is an advantage.

 

The second will perform considerably better at reducing sound transfer from one side of the wall to the other. In fact in that void using 75mm rockwool in a 100mm void making sure it only touches one layer of plaster board will further improve it's soundproofing ability.

 

Egg cartons do not do anything....

 

There are BBC monographs on types of sound isolating wall design I will see what I can dig out. The reason that the foam/barrier Matt composite works well and the idea of spacing the barrier Matt from the hull with rock wool behind is because it becomes more effective as it is able to work independently of the hull or bulkhead. Just like:

Plaster board : air gap : plaster board

Is more effective than

Plaster board : plaster board (no air gap)