Rigid vs. Fluffy

[sizzlemeister]

The question was raised last month at Music Player (and recently cross-posted here). Despite a lot of digging and reading I really haven't found much information on the differences other than little bits here and there.

The R-factor of rigid insulation is significantly lower than the R-factor of fluffy on average, and the cost is about triple to quadruple. Now, as I've come to understand it, the greater the R-factor, the greater the dampening effect insulation has as a general rule (due to density).

While rigid has consistent density throughout its plane and does not require support, its expensive, hard to obtain, low in R-value, and isn't very malleable.

Fluffy has greater R-values, is easy and cheap to obtain, can be made to fit nearly any structure and can be stacked to increase density.

Am I missing something here? Why use rigid over fluffy in sound-proofing applications? Why is rigid, like, "all the rage" and people are going to great lengths to get 703?

 

[apl]

Now, as I've come to understand it, the greater the R-factor, the greater the dampening effect insulation has as a general rule (due to density).

Dampening is making something wet. Damping is converting motion to heat.

Your understanding is not correct. There is no correlation.

And this stuff is not for soundproofing; that requires barrier materials that are typically limp and heavy and isolation systems that mechanically decouple structural elements.

Sorry 'bout sounding so snooty.

 

[sizzlemeister]

Dampening is making something wet. Damping is converting motion to heat.

http://www.m-w.com/cgi-bin/dictionary?book=Dictionary&va=Dampening&x=13&y=20

"1 : to check or diminish the activity or vigor of : DEADEN <the heat dampened our spirits>

2 : to become deadened or depressed"

Your understanding is not correct. There is no correlation.

And this stuff is not for soundproofing; that requires barrier materials that are typically limp and heavy and isolation systems that mechanically decouple structural elements.

Sorry 'bout sounding so snooty.

Thanks. I understand the basics of how to soundproof. Apparently you missed the posts around the internet regarding using rigid insulation to HELP soundproof a space.

 

[Mach311]

I've been thinking about this too. Here is a comparison chart to look at. Last night I made a bass trap using the fluffy pink stuff, since I had some extra laying around. I was able to squish two 3.5" layers into a 2x4 frame. Based on what I've seen I find it hard to justify the expense and aggravation of ordering the rigid stuff. Granted, it was a pain working with that itchy stuff and trying to keep it from bulging out beyond the frame, but with some hooks and some rigid wire you can fix that. Total $$ spent = 10.00

 

[mshilarious]

I've been thinking about this too. Here is a comparison chart to look at. Last night I made a bass trap using the fluffy pink stuff, since I had some extra laying around. I was able to squish two 3.5" layers into a 2x4 frame. Based on what I've seen I find it hard to justify the expense and aggravation of ordering the rigid stuff. Granted, it was a pain working with that itchy stuff and trying to keep it from bulging out beyond the frame, but with some hooks and some rigid wire you can fix that. Total $$ spent = 10.00

Part of it is that professional installations aren't like homemade traps and they can't be done with the fluffy stuff. Also if you cram 7" of insulation into a 4" frame, you will change the absorption properties, which might be a good thing, but it is no longer a rated assembly.

 

[apl]

http://www.m-w.com/cgi-bin/dictionary?book=Dictionary&va=Dampening&x=13&y=20

"1 : to check or diminish the activity or vigor of : DEADEN <the heat dampened our spirits>

2 : to become deadened or depressed"



Thanks. I understand the basics of how to soundproof. Apparently you missed the posts around the internet regarding using rigid insulation to HELP soundproof a space.

My apologies. I didn't like the way my post read so I added the remark about snootiness, but it didn't help.

 

[HangDawg]

I thought to absorb bass, you need density not R-value. R-value is the thermal rating. I don't think you could make the fluffy crap as dense as 703 unless you soaked it with some type of binder (glue) and compressed it. Of course, you'd have something similar to 703 then.

 

[HangDawg]

Now, as I've come to understand it, the greater the R-factor, the greater the dampening effect insulation has as a general rule (due to density).
?

That just doesn't make sense. Are you saying that the pink fluffy stuff is denser than the rigid 703? Hmmm, not in my house it isn't.

 

[Mach311]

I thought to absorb bass, you need density not R-value. R-value is the thermal rating. I don't think you could make the fluffy crap as dense as 703 unless you soaked it with some type of binder (glue) and compressed it. Of course, you'd have something similar to 703 then.

If you look at the chart I linked to, you can see that it shows sound absorption comparisons.

"This info states that plain 6" r19 kraft faced insulation uncompressed, is better at 125hz frequency than OC701, OC703, or OC705."

 

[HangDawg]

I guess the numbers look that way. I still wouldn't use it because I wouldn't want to have 6" of fluffy pink shit 16" off the walls when 3" of rigid 4" off the wall works as good or better.

I'd still like to hear from some of the experts on this.

 

[mshilarious]

If you look at the chart I linked to, you can see that it shows sound absorption comparisons.

"This info states that plain 6" r19 kraft faced insulation uncompressed, is better at 125hz frequency than OC701, OC703, or OC705."

Not at the same thickness - 6" 703 is rated at 1.19 @ 125Hz, vs. 0.94 for 6.5" of the fluffy stuff. And then there's the difficulty of mounting fluffy insulation on the surface of a wall, and you would have a problem with fire ratings with a paper facing on the surface of a wall.

Again, if you are building a bass trap, the fluffy stuff works fine, but you won't hear recommendations from pros to use it because it doesn't work for them. Pro studios can't or don't want to use 2"x4" framed bass traps when they can get installed, rated systems using rigid fiberglass.

 

[Mach311]

I guess the numbers look that way. I still wouldn't use it because I wouldn't want to have 6" of fluffy pink shit 16" off the walls when 3" of rigid 4" off the wall works as good or better.

Yeah, and costs 5 times as much.

I compressed it down to 4". It looks good, you can't tell it's the "fluffy pink shit" unless you disassemble it.

 

[Mach311]

Not at the same thickness - 6" 703 is rated at 1.19 @ 125Hz, vs. 0.94 for 6.5" of the fluffy stuff.

yeah, I know. But it seems most everyone recommends the 4" 703. So I was comparing the standard, so to speak. You gotta admit, for the price difference, 0.94 is a pretty good rating.

 

[sizzlemeister]

That just doesn't make sense. Are you saying that the pink fluffy stuff is denser than the rigid 703? Hmmm, not in my house it isn't.

A greater R-value means there's a greater density of air pockets which resist cold or heat. According the definitions of r-value here: http://ceramicadditive.com/facts.html and http://www.ibpteam.com/about/faq.asp among other places. Clearly they're talking about conventional forms of insulation, but then again so are we.

And isn't the principle, as APL noted, to stop, retard, dampen the transfer of energy? And, mass aside, isn't this accomplished effectively by using air pockets of some form or another (remember, I said HELP in sound proofing, not be the all-be-it-end-all-solution).

 

[scottboyher]

I can't believe this hasnt been discussed before.. The price difference and the numbers justify the fluffy stuff for a modest home studio.

 

[sizzlemeister]

Not at the same thickness - 6" 703 is rated at 1.19 @ 125Hz, vs. 0.94 for 6.5" of the fluffy stuff. And then there's the difficulty of mounting fluffy insulation on the surface of a wall, and you would have a problem with fire ratings with a paper facing on the surface of a wall.

Again, if you are building a bass trap, the fluffy stuff works fine, but you won't hear recommendations from pros to use it because it doesn't work for them. Pro studios can't or don't want to use 2"x4" framed bass traps when they can get installed, rated systems using rigid fiberglass.

Why would you mount anything to the surface of a wall when you are SOUND PROOFING, as opposed to attenuating frequencies and/or stopping transients? I can't imagine it'd be very effective.

I'm talking strictly sound proofing, not traps or clouds or those types of things.

 

[apl]

And isn't the principle, as APL noted, to stop, retard, dampen the transfer of energy? And, mass aside, isn't this accomplished effectively by using air pockets of some form or another (remember, I said HELP in sound proofing, not be the all-be-it-end-all-solution).

The absorptive properties of a given material has to do with the tortuous pathways the molecules have to flow through as the wave tries to propogate through the material. It has more to do with the geometry than mass.

 

[HangDawg]

Why would you mount anything to the surface of a wall when you are SOUND PROOFING, as opposed to attenuating frequencies and/or stopping transients? I can't imagine it'd be very effective.

I'm talking strictly sound proofing, not traps or clouds or those types of things.

Again, I think you are mistaken. Fiberglass, rigid or not, is not the main factor when speaking of stopping the transmission of sound. Wouldn't drywall be considered mounted "to the wall"? I think it's pretty usefull for isolation purposes. There seems to be alot of confusion in this thread. And it's confusing me more than I usually am.

 

[HangDawg]

It has more to do with the geometry than mass.

 

[sizzlemeister]

Again, I think you are mistaken. Fiberglass, rigid or not, is not the main factor when speaking of stopping the transmission of sound. Wouldn't drywall be considered mounted "to the wall"? I think it's pretty usefull for isolation purposes. There seems to be alot of confusion in this thread. And it's confusing me more than I usually am.

I always thought drywall WAS the wall.

So, to make a soundproofed wall, you have sheetrock, maybe another layer of sheetrock, resiliant channel, stud, NOTHING, stud, another layer of sheetrock. The sheetrock layers being varying thicknesses, the studs staggered.

This is what you're suggesting, then? Nothing in the wall cavity at all to HELP stop sound transmission?