recording studio sound deadening foam panels

[gs1949]

I've read that about rockwool too. And for me, the term rockwool brings to mind, perhaps incorrectly, asbestos.

I used to work for the Yukon Forest Service. On 2 different occasions I was sent to Clinton Creek, a now defunct asbestos mining town north of Dawson City. It was an incredibly depressing place. Many trees were dead and gray, smothered by dust.

Asbestos and asbestosis terrify me. My father had asbestos in one of his lungs from working in a shipyard in the 40s, but that wasn't what killed him.

So I am prejudiced against rock wool and will stick with closed cell foam, even if I must add something to avoid being deafened in an Alberta hailstorm.

[Sleddgracer]

Originally Posted by gs1949

I've read that about rockwool too. And for me, the term rockwool brings to mind, perhaps incorrectly, asbestos.

I used to work for the Yukon Forest Service. On 2 different occasions I was sent to Clinton Creek, a now defunct asbestos mining town north of Dawson City. Asbestos and asbestosis terrifies me. My father had asbestos in one of his lungs from working in a shipyard, but that wasn't what killed him.

So I am prejudiced against rock wool and will stick with closed cell foam, even if I must add something to avoid being deafened in an Alberta hailstorm.

rockwoll is made from ancient lava - no asbestos in it - the way they are forming the bats now kind of makes that option more interesting to me, at least for the walls - no styrofoam squeaks

[gs1949]

If enough of it is used, Loctite PL 300 should put a stop to any squeaking.

[musigenesis]

Originally Posted by gs1949

I've read that about rockwool too. And for me, the term rockwool brings to mind, perhaps incorrectly, asbestos.

I used to work for the Yukon Forest Service. On 2 different occasions I was sent to Clinton Creek, a now defunct asbestos mining town north of Dawson City. It was an incredibly depressing place. Many trees were dead and gray, smothered by dust.

Asbestos and asbestosis terrify me. My father had asbestos in one of his lungs from working in a shipyard in the 40s, but that wasn't what killed him.

So I am prejudiced against rock wool and will stick with closed cell foam, even if I must add something to avoid being deafened in an Alberta hailstorm.

I can't speak to there being nothing else toxic in rock wool, but there's no asbestos in it. It's basically melted lava rock and slag from steel production spun into fibers, mixed with oil and pressed.

[gs1949]

Pressed into panels or is it more flexible?

[musigenesis]

Originally Posted by gs1949

Pressed into panels or is it more flexible?

It usually comes in 2'x4'x2" bats, kind of like fiberglass but no backing paper. That's the other big advantage for me: it's flexible like a blanket so it would handle the slightly curved roof with no problem. I'm also planning on making insulated curtain-type-things that will cover the windows when it's cold, and fabric-covered rock wool would work pretty well for this.

[o1marc]

No one has mnetioned they sound difference when using a rubber roof coating? Surely it dampens the bare sheet metal sound. But how much?

[gs1949]

@o1marc, I've seen a little data on that. Some types of elastomeric finishes do provide some sound deadening. I will be researching that more and I can post some on what I find.

[gs1949]

@musigenesis, I intend to make some things to go on windows very similar to what you describe. But mine will be protected by gluing the foamboard onto some thin luan plywood, then wrapping it all with cloth glued in place, and then adding magnets or velcro or both to hold it to the window. Same idea, just stiff.

[Drew Bru]

Originally Posted by gs1949

I've read that about rockwool too. And for me, the term rockwool brings to mind, perhaps incorrectly, asbestos.

I used to work for the Yukon Forest Service. On 2 different occasions I was sent to Clinton Creek, a now defunct asbestos mining town north of Dawson City. It was an incredibly depressing place. Many trees were dead and gray, smothered by dust.

Asbestos and asbestosis terrify me. My father had asbestos in one of his lungs from working in a shipyard in the 40s, but that wasn't what killed him.

So I am prejudiced against rock wool and will stick with closed cell foam, even if I must add something to avoid being deafened in an Alberta hailstorm.

We started down the road of Rockwool but got a little scared because of the possibility of airborn fibers. Also heard that it can retain moisture and contribute to mold problems. I have no idea if these are valid concerns or not, but we chose foamboard. There are no noticable squeaks, and considering the engine noise I'm not sure I would notice them anyway.

[EastCoastCB]

Originally Posted by Sleddgracer

rockwoll is made from ancient lava - no asbestos in it - the way they are forming the bats now kind of makes that option more interesting to me, at least for the walls - no styrofoam squeaks

You're correct about it not being asbestos-

ROCKWOOL insulation is a stone-based mineral fiber insulation comprised of Basalt rock and Recycled Slag. The recycled content in mineral wool is derived from the steel slag.

[Seriousracer]

I have the rockwoll in my bus and over my engine cover. It works o also used the the sound absorbing foam on the ceiling it works but what I found a 1/4 3/16 inch plywood made the foam worked better than just putting it on the steel.
I want the roof to breathe so that is why I went with the acoustic foam. It helps

[Rock-N-Ruth]

If it is rain on your tin roof that annoys you the most, just glue shag carpet to your roof. That will lessen the impact of the raindrops and give your bus a unique look. You could even substitute Astro turf for the carpet.

[JustKip]

^^^
or plant a lawn

[yugogypsy]

Ask Accordion if he's still walking this earth, last I heard he wasn't well

[musigenesis]

Originally Posted by Rock-N-Ruth

glue shag carpet to your roof. That will lessen the impact of the raindrops and give your bus a unique look.

Unique smell, too. These ideas are getting dumb and dumber, you might say.

[Rock-N-Ruth]

Originally Posted by JustKip

^^^
or plant a lawn

Build a sandbox the length of the roof and call it a mobile beach.

[musigenesis]

Originally Posted by Seriousracer

I have the rockwoll in my bus and over my engine cover. It works o also used the the sound absorbing foam on the ceiling it works but what I found a 1/4 3/16 inch plywood made the foam worked better than just putting it on the steel.
I want the roof to breathe so that is why I went with the acoustic foam. It helps

How's the rock wool working out as far as thermal insulation is concerned?

[PerfectInsanity]

I've done extensive research into this, more than I care to admit, and here's what I've found, starting with what else has been mentioned here. Part of the challenge is this has not been done/documented before, so knowing what translates from home strategies to a moving vehicle takes a lot of consideration. My build is going to incorporate many strategies. (we're looking to eliminate road and engine noise to reduce stress of our pets while driving)

The acoustic foam panels you mention MikeTheBard already addressed and I can't see anything to add, other than reinforcing his statements. They'd not keep outside noise from getting in, only inside from getting out and bouncing around the space.

Regarding MLV (mass loaded vinyl) -- or your thick rubber flooring: In order for it to work, it has to be decoupled/separated from the source you're intending to block sound from, to reduce transfer of vibration/sound directly through the mass, making it nearly pointless. For example, if you're wanting to use that over the wheel wells, you need to stick some thin closed cell foam sheet or felt or something along those lines to isolate it. Further, that means it cannot have weight directly on it or it'll compress that foam making it useless. I was going to go this route and bailed on it. MLV is a cheaper alternative to buying lead sheeting, though barely, and simply too expensive and too complicated to integrate into a bus. It's also really expensive, even from some of the cheapest sources I found that paid for shipping (which is insanely expensive, as you're buying weight), and a very uneconomical way to add mass.

Regarding CLD material/Dynamat and clones/vibration dampening: As others pointed out, this is crucial since we're in a giant metal tube/box. This is what I consider one of the biggest bang for your buck areas. You only need 25% coverage for gain near the performance of 100% coverage (that extra 75% has severely diminishing returns). Also, there IS a significant difference between actual CLD material and roofing materials, will not give good performance. And there's a huge variety of butyl sources/types used in the various CLD products out there, most of which are not actually acoustically purposed and do not perform well. (and some smell strongly) There are many posts/tests I found about this. The best bang for your buck performance I found is Kno Knoise Kolossus Edition. I saw the Noico and was tempted to give it a try, but I could not find actual tests indicating its effectiveness and after seeing how poorly (by comparison) other cheaper solutions fared in testing, I passed on it. Maybe it could be a good budget compromise? No way to know at this point, aside from what solvo stated -- though I'm curious if that was 100% coverage ("every panel") or just means patches were put on all panels. My approach is 25% coverage of each panel (inside of weld/seams).

Acoustic insulation is the next avenue you'd want to consider. Foam board and spray foam does VERY little to block noise. I mistakenly thought it did based on uninformed posts I found all over various bus posts and groups, but after researching how sound dampening and/or proofing works, it's clear it does not. I will use 1/2" of XPS as my thermal break layer on the floor, on top of the CLD patches. Beyond that, I've chosen the Rockwool route also, though a combination of products. I'll be using ComfortBoard/Rockboard 80 in the floor (inside 2x3 studs), around the wheel wells (thicker even), and engine bay/deck/bench (also thicker). Zoro sells this for pretty cheap in 1 1/2" thickness (barely more than the 1"), especially with their coupon deals and free shipping. This heavier weight material is much better at blocking lower frequencies (coming from those lower structure sources -- tires/engine/road noise). There are fiberglass equivalents (Owens Corning 703), and other brand mineral wool equivalents (Thermafiber as well, should you prefer. In the walls (bare metal from re-skinning) and ceiling (on top of stock 1" to 1.5" stock spray foam -- not uniform, sadly), I'll be using SafeNSound batting.

A huge factor in trying to reduce noise intrusion into our buses is just how much noise resonates through the entire structure. In researching this topic, it's clear small leak points in your sound 'shield' can negate a lot of effort/investment. Do lower frequencies from engine noise in a rear engine bus make it all the way to the front via the frame? Or via other flanking paths, such as through the floor into the walls, back down to other parts of the floor or ceiling? Further, how much work is negated by having windows (insulated or not) in your walls?

I'm simply doing what I can to limit noise as much as I can, and have toned down what I'd initially built a plan around for fear of wasting money. What I noted above is not my entire strategy, just the main points. Hopefully, it helps, and I'll try to check back in on this post for follow-up. There's plenty I'm not thinking of right now, I'm sure. Re-skinning my bus now, so pretty busy.

[kidharris]

Originally Posted by MikeTheBard

So, I might actually be able to help here. I'm a recording musician, worked as a theatre tech, done sound control on my home studio, and know a bit about the subject.

I could give you links for a few college courses worth of physics and wavelengths of frequencies and properties of specific materials, but honestly, all of the deep technical math can be dumbed down to a few practical principles-

• Hard, smooth surfaces reflect sound.
• Soft, rough surfaces absorb sound.
• Parallel surfaces can amplify sounds or create feedback.
• Pretty much anything that vibrates will transmit or amplify sound.
• To that end, soundproofing requires controlling vibration.

Again, my experience is largely based around recording studios and theatres, but you might still find something useful, and I'm happy to help with questions.

For a studio, for example, a lot of thought goes into mixing hard and soft surfaces to tune the room for just the right amount of natural reverb. This is also something that's done a lot for restaurants, to keep the noise level down. I have a bunch of 18" squares on my wall that I made from quilt batting and burlap or felt over a backing board. They do far more to keep the room quiet than you would think- I'm using them like that studio foam you're looking at. They do 90% of the job for 10% of the cost. For restaurants and such, they make panels with a wood frame and basically just batting or acoustic ceiling tiles, and fabric- They sell for absurd prices.

Anyway, that's basically what you're looking at with studio foam- It's for absorbing sound inside the room. I'm not saying it wouldn't help, or that it wouldn't make a decent insulator, but I'm not sure it's ideal for what you're thinking.

A fully soundproof room like you'd find in an expensive studio- an isolation booth- is often a solid room inside a slightly larger room. It floats on a thick rubber pad, and has a few inches of dead air space between double walls and windows. This means that when something causes the inner room to vibrate (like a loud amplifier), that vibration isn't carried to the outer room- And vice versa.

Sheet metal vibrates a lot- Especially when you have largish unsupported sections of it. Hence the noise. So the first thing we're going to want to do is to stop it from vibrating. This is ultimately going to be more effective than trying to quiet the noise after the fact.

Placing a layer of insulation against the metal goes a long way- But bear in mind that the more hard/rigid the insulation is, the more it itself will vibrate. Admittedly, it will be far less than the metal, but still enough to not be ideal.

I'm speculating at this point, but I'm wondering if a layer of something like EVA foam glued directly to the steel roof, before putting on a styrofoam insulation, might do wonders for killing the sound. I've been working with the stuff a bit lately, and I think it's got just enough weight and elasticity to dampen the vibration of the metal.

I'm going to play with that a bit and get back to you.

About 10 years ago I did some research on sound deadening to try to stop my neighbors complaining. I don't remember everything that I learned but maybe enough to be of help.


Sound studios, office spaces, resturants, malls, etc are mostly trying to stop/control reverb or reflections of sound inside of a room, not stop it from coming thru a wall, although that may also be necessary. I think you are more interested in stopping sound transmission.


To manage sound you need to understand how sound travels. Yes, sound is vibrations - sort of. Something stiff and lightweight vibrates easily, think drum head (stiff and heavy - think concrete wall - also vibrates, just takes more energy). Consider the outside of the drum head. As the material vibrates and moves outward it causes the out side air pressure to momentarily increase, then as it moves back inward the outside air pressure decreases. This causes a sound wave with a frequency (how fast the vibration is) and a volume (amount of energy). This rise and fall of the air pressure on your ear drums is what you refer to as sound.


Sound needs a media (air, water, steel, etc.) to travel in. It cannot travel in a vacuum. The further a sound travels the weaker the volume gets (loses energy) How much of the sphere the sound is projecting into also controls the volume, which is why speakers put in the corner sound louder than speakers in the center of a wall which are louder then speakers in the center of the room.



Sound doesn't travel thru solid materials like it does fluids (high/low pressure waves). What it does is go thru holes or cause the solid surface to vibrate and restart the sound on the other side. It takes more energy to vibrate heavier materials which is why they reduce or kill the sound (don't vibrate enough to restart the sound on the other side or only restart a weaker version). Bass (low frequency) travels through solids better than treble (high frequency).


Soft, stringy. or gummy materials also kill/reduce sound because they vibrate internally and convert the energy to heat energy instead of the sound waves in air that your ears pick up. Hard foam vibrate and are not as good at stopping sound as soft foams. Many studio type foams let the sound go thru the holes in the foam but do not reflect the sound, which is why they are used. The sound can still go thru the walls. Fiber glass insulation is pretty good for stopping sound transmission. Heavy curtains are also good. Sound curtains are made by sewing fiberglass between 2 layers of curtains.


Specifically, in your case, if you can stop the metal from vibrating with the rain, then you will be better off than trying to stop the sound after it is created. There are expensive coatings that are advertised to deaden sound that have tiny hollow spheres embedded. I am skeptical. A soft, heavy elastomeric roof coating may work (maybe with a sunscreen embeded in it, 2 coats of elastomeric? - you be the guinea pig - at least it shouldn't leak and will be cooler in the summer? probable be a dirt collector?). Or a rubber EPDM roof.


Heavy material adhered to the bottom of the roof metal may help. A light weight deck/solar panels above the roof would probably help dampen the force/energy of the rain, no pun intended.


Perhaps, if you are parked you could temporarily put/lay a sunscreen/net over the roof to breakup/slow the raindrops (absorb the energy from the rain) You could also park under a roof/bridge until the rain stops.


Should you decide to try to stop the sound transmission, you should also understand STC ratings if you want to find cheap materials to deaden sound. This link is not a recommendation by me, it is just the first link I saw when I searched for "STC rating" I didn't even read it.


https://www.soundproofingcompany.com...nd-stc-ratings


It is easier to make progress and figure out if something is going to work out if you buy a sound meter.


Any thing between you and the sound source is going to help dampen the sound. All of the products that I have seen sold for sound deadening are outrageously expensive and are usually heavy.


In my experiments, I found a couple of cheap, light weight solutions.


Go dumpster diving at a small sign company and look for discarded magnetic sign material. It is thin, fairly heavy and helps a lot for the amount of weight and volume that it takes up. Cut it to fit closelyon the bottom of the roof. If I was using it inside my ceiling to stick to the roof, I would not trust the magnetic ability but would help it out with some adhesive, which will also help with the sound blocking, before I covered it up.


If you live close to an active convention center, after a convention you may find magnetic signs in the trash there, but you may also find some thin vinyl sheet material that they use to cover table tops and use for masking off poles and other unsightly structures during conventions. Some experimentation with this stuff as curtains was very useful to me, but I'm not sure if it could be useful in a bus. Heavy carpets work good on walls and ceiling, to stop noise (popular with the hippies in the 1960's). Most thermal insulations also have some value as sound deadeners (this is one area where you can get a material to do 2 jobs, 3 if it also has an acceptable finish, like vinyl flooring. Most drop ceiling tiles are good, but have no strength. Check the STC ratings on materials at your big box stores. A lot of floor and ceiling materials have good STCs. An amazing amount of useful material goes in the trash at the convention centers, but they are not very receptive to allowing people to go thru the trash.


Torch down roofing may work, glued down under a plywood deck, for the floor (don't torch it down..LOL). Cheap...could use scraps or factory seconds, soft, thin, and heavy...all good properties for sound deadening. Probably too heavy (.7-1 lb/sq ft) to glue up to the ceiling. Used a lot of it for roofing but never got around to checking out its sound properties.



For me, researching under "vibration dampening" was more productive than researching "sound control", which mostly pulls up sites trying to sell you overpriced stuff. One very good technique is adhering different materials together especially (but not absolutely necessary, depending on materials) with a soft material (rubber, silicon, etc) or adhesive in between. Forgot what they call it. I always wanted to experiment with epoxy coatings with soft aggregate mixed in.

Gotta go now, I'm tired of typing. Good luck.