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Old 08-25-2019, 09:37 AM   #41
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Dynamat, Fatmat, Noico, and many others are automotive sound insulation products -- and they're all pricey...

A lot of folks have had good success with using the "stick n' peel" rolls of roofing material from Loewes or Home Depot... They are a similar product but much cheaper.

Just try and be sure it's a butyl based product and not asphalt based...

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Old 08-25-2019, 11:05 AM   #42
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wow. this is exhausting. I'm going with the earplugs idea.
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Old 08-25-2019, 09:48 PM   #43
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I'm planning on spray foaming the ceiling and wall for thermal insulation. This should also stiffen the sheet metal so that it doesn't vibrate as much. I'm then planning on covering the interior walls with aluminum sheet metal. I like the look of the airstream camper interiors. I'm thinking of using a self adhesive or spray on vibration damping material between the aluminum and spray foam.

For the floor I'm thinking closed cell foam board for insulation and then aluminum sheet for my radiant floor system with lineX or rhino lining type surface on top...if I can afford it.

Ted
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Old 08-26-2019, 01:23 PM   #44
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I'm planning on spray foaming the ceiling and wall for thermal insulation. This should also stiffen the sheet metal so that it doesn't vibrate as much. I'm then planning on covering the interior walls with aluminum sheet metal. I like the look of the airstream camper interiors. I'm thinking of using a self adhesive or spray on vibration damping material between the aluminum and spray foam.

For the floor I'm thinking closed cell foam board for insulation and then aluminum sheet for my radiant floor system with lineX or rhino lining type surface on top...if I can afford it.

Ted

It never occurred to me that the foam would stiffen the roof skin against vibrating, something to think about.


A caulk like (thick) adhesive between the inner aluminum sheet and the ribs of the roof would also serve as a thermal and sound break and to prevent galvanic corrosion (dissimilar metals )of the aluminum. Theoretically, when fastening aluminum to steel, stainless fasteners should be used, especially if the joint is going to get wet with water which accelerates galvanic corrosion. Of course, I don't see this happening on the interior.
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Old 08-28-2019, 05:49 PM   #45
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Show me the dB's!


12mm (1/2”) Cork Underlayment = 48 dB


Dynamat, X-Mat and similar stick-on sound-deadening products = 19 dB


I plan on using tropi-cool elasometric roof coating on exterior
Glue 1/4" cork underlayment leftover from the floors on the metal walls and ceilings below rockwool batt insulation


Should do the trick in my Diesel Thomas Vista Shorty with a front engine


Also plan on creating a sound-deadening box around the engine bay as well
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Old 08-28-2019, 06:05 PM   #46
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It never occurred to me that the foam would stiffen the roof skin against vibrating, something to think about.
I think that's only true to the extent that it would stiffen the skin and keep it from vibrating (or flapping) while driving; it wouldn't inhibit the conduction of sound from the outside to the interior, except for whatever effect the foam itself has (which is apparently not much). The foam stiffness might deaden the sound of objects falling on the roof (e.g. rain) which would certainly be a good thing.
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Old 08-28-2019, 08:21 PM   #47
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@Shorty22, so comparing 48dB to 19 dB would be like an almost 500 percent reduction compared to an almost 200 percent reduction, is that correct? Or is my arithmetic flawed again, and it's 50 to 20? But I can see it's significant.
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Old 08-28-2019, 08:33 PM   #48
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I can't find these dB numbers you're referring to.
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Old 08-28-2019, 10:22 PM   #49
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I can't find these dB numbers you're referring to.
Try these sources...


https://www.cancork.com/cork-natural...oor-and-walls/

https://www.eastwood.com/xmat-sound-...4-8-sq-ft.html
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Old 08-28-2019, 10:34 PM   #50
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@Shorty22, so comparing 48dB to 19 dB would be like an almost 500 percent reduction compared to an almost 200 percent reduction, is that correct? Or is my arithmetic flawed again, and it's 50 to 20? But I can see it's significant.
Not sure about percentages...but if you have the sound of a diesel truck 10 meters away (90 dB), and install 1/2" cork insulation to your interior space, the 49 dB sound deadening properties of cork will insulate the sound of that diesel engine down to about 40 dB, which would be equivalent to the level of sound in a quiet library.
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Old 08-28-2019, 10:35 PM   #51
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@Shorty22, so comparing 48dB to 19 dB would be like an almost 500 percent reduction compared to an almost 200 percent reduction, is that correct? Or is my arithmetic flawed again, and it's 50 to 20? But I can see it's significant.
Each 10 dB is roughly equivalent to a halving of the perceived loudness, so 48 dB would reduce the loudness to 1 / (2 ^ 5) or about 3% (which you would probably describe as a 97% reduction - any reduction over 100% would be negative which wouldn't really make sense for sound levels). 19 dB would be 1 / (2 ^ 2) or about 25%, a 75% reduction.
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Old 08-28-2019, 10:47 PM   #52
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Not sure about percentages...but if you have the sound of a diesel truck 10 meters away (90 dB), and install 1/2" cork insulation to your interior space, the 49 dB sound deadening properties of cork will insulate the sound of that diesel engine down to about 40 dB, which would be equivalent to the level of sound in a quiet library.
This link: https://bettersoundproofing.com/is-c...soundproofing/

... interestingly enough repeats the 3/32" of cork is good for 10 dB (which is where the claim for 1/2" being good for 48 dB is extrapolated from), but later states that 2.4" of cork gives you 50 dB. I think this latter figure makes sense and the 1/2" = 48 dB really doesn't.
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Old 08-29-2019, 03:10 AM   #53
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This link: https://bettersoundproofing.com/is-c...soundproofing/

... interestingly enough repeats the 3/32" of cork is good for 10 dB (which is where the claim for 1/2" being good for 48 dB is extrapolated from), but later states that 2.4" of cork gives you 50 dB. I think this latter figure makes sense and the 1/2" = 48 dB really doesn't.



I took a quick look at that link and unless you are trying to reduce the ambient noise produced by activity inside of the bus OR kill the thud from someone walking on your roof, I believe cork would be a waste of time. This link is an advertisement to sell cork. You notice they try to push the NRC value but avoid telling you the STC value.



In addition cork would be exceedingly hard to apply as a seamless well attached sheet to a bus ceiling, unless you are planning on putting in a dropped ceiling or applying it as the outer exposed surface on a paneled ceiling. This product is intended more for stopping echo in a studio/workplace environment OR lowering foot fall noises as an underlayment for floors.



"Itís time for a quick science lesson." That should be translated as "Itís time for a quick pseudo mumbo jumbo BS science lesson"
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Old 08-29-2019, 07:33 AM   #54
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I took a quick look at that link
I probably read the link even less than you. My point was basically that a half-inch of cork providing 50 dB of sound attenuation is pretty fanciful, but I can't seem to find a good source for cork properties that isn't an ad of some sort.
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Old 08-29-2019, 03:06 PM   #55
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@kidharris

that was an example link for cork. Re: STC, the bottom of the link it states 1/2" cork underlayment has an STC rating of 89.

I've just been researching the best I can, so thanks for the feedback. Looks like an STC rating of 89 is better than most standard home acoustic assembly performance:

http://www.usg.com/content/dam/USG_M...s-en-SA200.pdf

I have a lot of leftover cork underlayment, since I planned on purchasing in bulk so I can use this on the walls behind rockwool insulation. Cannot offer much more reasoning, but I can update you all after the build to show how it goes
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Old 08-29-2019, 05:23 PM   #56
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@kidharris

that was an example link for cork. Re: STC, the bottom of the link it states 1/2" cork underlayment has an STC rating of 89.

I've just been researching the best I can, so thanks for the feedback. Looks like an STC rating of 89 is better than most standard home acoustic assembly performance:

http://www.usg.com/content/dam/USG_M...s-en-SA200.pdf

I have a lot of leftover cork underlayment, since I planned on purchasing in bulk so I can use this on the walls behind rockwool insulation. Cannot offer much more reasoning, but I can update you all after the build to show how it goes

I am not seeing what you are. I saw the STC rating but I think it was used out of context, 89 is an exceptionally high rating and is probably for the entire floor assembly, which is usually the case. The writer was not specific enough to make the determination that you made. This is common in advertisements to try to mislead without actually doing an outright lie. At any case I believe what they are talking about is for floor underlayment to lower the transmission of footfall sounds (people walking on the second floor) or the thud when they drop something.


unless you are going to put it under your floor covering to avoid waking any animals sleeping under your bus I would do a little more research before spending my money. 1/2" thick cork floor underlayment panels will be hard to conform to and attach to the curves of a bus roof and even on walls you would have gaps where the ribs were. I think I would just stick to the rockwool/fiberglass, maybe with some kind of soft rubbery coating (cheaper elastomeric roof coating?) sprayed/rolled/brushed to the inside surface of the sheetmetal to provide damping and additional water proofing (could also work as an adhesive to hold the rockwool or fiberglass. Perhaps I am not understanding your intentions/needs.
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