I´m posting this message in this group aswell (no replies in the "building products" group).. hope for better luck..=)
Hi...
I have some q´s about insulation.
I´ve been reading this forum for a couple of months and i´ve seen everybody talking about 2.5-3 pcf insulation is the way to go when isolating your studio
Is density the only factor that matters when choosing insulation type?
What is the "lamda" (don´t know if that´s the right name for it in english, it´s the same sign as in wavelength) figures in specs??
I figure it has something to do with heat??
Because in Sweden most insulationproducts don´t come with densityfigures but only with the "lamda" figures (37, 39 etc for example)
Thankful for any kind of help... sorry about my english...
Andy
insulation question bump
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ponkass
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knightfly
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No need to apologise for your English, it beats the crap out of my Swedish 
I'm not sure what Lambda would mean, although those values suggest it might be KG per cubic meter density; if so, 40 to 48 would be the correct value. You could probably tell by the range of these values; if they run from a low of about 16 to a high of about 100 or so, then they are probably metric density of kG per Cubic Meter.
One of our more learned members, Eric Desart, speaks four languages - not sure if one of those is Swedish, but perhaps he's heard of that parameter and can clear this up - Eric, you listening, you old rascal you??!?
Sorry that wasn't much help, may take a group effort here... Steve
I'm not sure what Lambda would mean, although those values suggest it might be KG per cubic meter density; if so, 40 to 48 would be the correct value. You could probably tell by the range of these values; if they run from a low of about 16 to a high of about 100 or so, then they are probably metric density of kG per Cubic Meter.
One of our more learned members, Eric Desart, speaks four languages - not sure if one of those is Swedish, but perhaps he's heard of that parameter and can clear this up - Eric, you listening, you old rascal you??!?
Sorry that wasn't much help, may take a group effort here... Steve
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ponkass
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hi Knightfly.. thanks for your reply... It´s not kg/cubic meter.. i know that..
i found this today: http://www.isover.se/produkter/visa_pro ... 3&typ=bygg
It´s in swedish but i think you´ll figure it out... =)
In this info lambda has something to do with temperture/heat.. but the numbers are not as high as in an add i saw in a paper. It said "lamda 37 or 39... blabla.. you don´t need to know density of insulation for isolation, only the lambda value is necessary".. or some crap like that.. that´s what made me think about it and post here.
But back to my first question... density is the only thing that matters??
Andy
i found this today: http://www.isover.se/produkter/visa_pro ... 3&typ=bygg
It´s in swedish but i think you´ll figure it out... =)
In this info lambda has something to do with temperture/heat.. but the numbers are not as high as in an add i saw in a paper. It said "lamda 37 or 39... blabla.. you don´t need to know density of insulation for isolation, only the lambda value is necessary".. or some crap like that.. that´s what made me think about it and post here.
But back to my first question... density is the only thing that matters??
Andy
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z60611
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Actually air-flow-resistitivity is a better guage than density.
If you're comparing density between rockwool (basalt/slag) and fiberglass (silicon) then you're comparing apples to oranges.
I think that you're looking for something around 50000 mks Rayls/m (rigid rockwool). Too much higher than that isn't good either.
A fluffy fiberglass batt is around 6000 mks Rays/m, and that's too low, but much better than empty air.
Unfortunately, before you go looking, I believe it's rare to see rayls figures published.
The 2.5pcf figure is for USG's THERMAFIBER, which is rockwool. From this page: http://www.usg.com/Design_Solutions/2_3 ... onperf.asp
On the other hand there's some good marketing in
http://www.owenscorning.com/worldwide/a ... eBro_E.pdf
which says "Although higher density mineral wool batts in open testing have higher Noise Reduction Coefficients and Rayles sound absorption values, on average lighter density QuietZone® Acoustical Batts have equivalent STC, sound transmission class ratings in gypsum board finished steel and wood stud walls and floor systems in building code tables."
Of course we're not interested in STC, I'm interested in using the insulation to damp the LF resonance of the gypsum panels. It's actually not surprising that lighter insulation doesn't change STC much, since STC is weighted higher up.
Nevertheless, it is my current inexperienced untrained belief (subject to change without notice, and currently without data) that the thicker the wall cavity is, the lower the rayls that is still ok. i.e. if the wall cavity is 3.5" thick (standard residential wall), I'd definately go for 2.5pcf rockwool. But if the wall cavity is 8" thick (double stud wall) then something lighter might be ok. How much less dense is optimal is still up in the air, but I doubt I'd go as far as fluffy pink for the entire cavity. Perhaps I'd go as low as 25000 mks Rayls/m without worrying about it, or mixing 3" of 2.5pcf rockwool with 5" of fluffy pink.
If you're comparing density between rockwool (basalt/slag) and fiberglass (silicon) then you're comparing apples to oranges.
I think that you're looking for something around 50000 mks Rayls/m (rigid rockwool). Too much higher than that isn't good either.
A fluffy fiberglass batt is around 6000 mks Rays/m, and that's too low, but much better than empty air.
Unfortunately, before you go looking, I believe it's rare to see rayls figures published.
The 2.5pcf figure is for USG's THERMAFIBER, which is rockwool. From this page: http://www.usg.com/Design_Solutions/2_3 ... onperf.asp
On the other hand there's some good marketing in
http://www.owenscorning.com/worldwide/a ... eBro_E.pdf
which says "Although higher density mineral wool batts in open testing have higher Noise Reduction Coefficients and Rayles sound absorption values, on average lighter density QuietZone® Acoustical Batts have equivalent STC, sound transmission class ratings in gypsum board finished steel and wood stud walls and floor systems in building code tables."
Of course we're not interested in STC, I'm interested in using the insulation to damp the LF resonance of the gypsum panels. It's actually not surprising that lighter insulation doesn't change STC much, since STC is weighted higher up.
Nevertheless, it is my current inexperienced untrained belief (subject to change without notice, and currently without data) that the thicker the wall cavity is, the lower the rayls that is still ok. i.e. if the wall cavity is 3.5" thick (standard residential wall), I'd definately go for 2.5pcf rockwool. But if the wall cavity is 8" thick (double stud wall) then something lighter might be ok. How much less dense is optimal is still up in the air, but I doubt I'd go as far as fluffy pink for the entire cavity. Perhaps I'd go as low as 25000 mks Rayls/m without worrying about it, or mixing 3" of 2.5pcf rockwool with 5" of fluffy pink.
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Eric_Desart
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My Swedish is as bad (can recognize some vocabulary via analogy when reading it).....knightfly wrote:No need to apologise for your English, it beats the crap out of my Swedish
I'm not sure what Lambda would mean, .....
Lambda stands here for heat transmission coeficient.
It expresses the amount of energy (Watt) that is transmitted trough a plain of 1 m2 with a thickness of 1 m per degree temperature difference between both sides in Kelvin or Celsius. The smaller this value the better the thermal insulation. So this value is a material property independent of thickness or use in constructions.
Lambda : [W/mK]
Density is expressed in formulas by the Greek small letter rho.
Often suppliers don't provide densities in commercial brochures (I think to make potential customers more dependent, and make comparison with competitors more difficult).
But they know, so one has to ask.
I know a producer who publishes densities for certain market segments and for other segments they don't. Marketing games I'm not familiar with.
Z is of course right, since not the density but mainly the gas flow resistivity is defining, but you won't find those numbers. They are VERY rarely published and often even not measured as such unknown for the representatives of the product themselves. And if measured it's for internal use (the lab guys).
Best regards - Eric Desart
My posts are never meant to sell whatever incl. myself, neither direct, nor indirect.
My posts are never meant to sell whatever incl. myself, neither direct, nor indirect.
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ponkass
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Innovations
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In the US lambda is called the R value. It is a measure of the thermal transmission. Unlike lambda large R values are better. Sound is measured in at least two, often three measures:
First is absorption this measures the fraction of sound that BOUNCES OFF of a surface. It is measured at several frequencies and is a ratio between the sound that is bounced off of this material and the amoung that is bounced off the best material at the time the dest was designed. That is how come you can have an absorbtion greater than one.
Next there is Sound Transmission Coefficient (STC). This is the amount of sound that doesnt go THROUGH the wall assembly. A wall assembly with a STC of 40 means that the sound on one side of the wall is 40 decibels less than the sound on the other side. The specification of this test says that only whole wall assemblies shouls be tested because much of the results can depend on fabrication techniques and the order and spacing of elements. Yet ceertain manufacturere will add a layer of a material to an existing tested wall assembly. Record the increase in isolation, and then claim that the material has a STC of X which implies that it would have that improvement no matter how and where applied. Not true.
Finally you might see a mention of Impact Isolation Class (IIC) which is usually a test of floor assemblies as to how much they translate note from being struck, such as being walked on.
First is absorption this measures the fraction of sound that BOUNCES OFF of a surface. It is measured at several frequencies and is a ratio between the sound that is bounced off of this material and the amoung that is bounced off the best material at the time the dest was designed. That is how come you can have an absorbtion greater than one.
Next there is Sound Transmission Coefficient (STC). This is the amount of sound that doesnt go THROUGH the wall assembly. A wall assembly with a STC of 40 means that the sound on one side of the wall is 40 decibels less than the sound on the other side. The specification of this test says that only whole wall assemblies shouls be tested because much of the results can depend on fabrication techniques and the order and spacing of elements. Yet ceertain manufacturere will add a layer of a material to an existing tested wall assembly. Record the increase in isolation, and then claim that the material has a STC of X which implies that it would have that improvement no matter how and where applied. Not true.
Finally you might see a mention of Impact Isolation Class (IIC) which is usually a test of floor assemblies as to how much they translate note from being struck, such as being walked on.
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knightfly
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Innovations, good info with the exception of the description of why absorption values get reported as being greater than one - what actually happens is that the test piece, which is typically 8 feet by 9 feet, is placed in position in the test room after checking levels at all frequencies used in the test, typically from 125 hZ up to 4000 hZ in octave bands - if ALL of a particular frequency is absorbed, the test piece is said to have an absorption coefficient of one, which is supposedly perfect, and would be also accomplished by an open window with no means of returning the sound.
However, some testers "hide" or mask, the edges of the test piece during the tests so as not to add extra absorption during the test - without this, it is possible for the test to return values of greater than one at some frequencies. Some manufacturers simply quote these values as measured, so we end up with absorption figures in some ranges of, say, 1.12 - It's not that this is really bogus, it's just not consistent unless EVERYONE does the test the same way. For example, you can get more useful absorption out of the exact same square footage of material, simply by cutting it into smaller pieces so that there is more edge surface exposed to the sound field - kind of "free" absorption, so to speak.
Some manufacturers state very plainly how their tests are done; things like distance of the material from the boundary wall, whether or not the edges were masked for the test, etc - generally, though, any time you see values in excess of 1.00 you can assume that the edges were NOT masked. YOu can NOT, however, assume that the rest of the test was done right without the proper test methods being stipulated.
These tests are a lot more complex than I've just covered (partly because I don't know all that's done in them yet myself), but that's generally why numbers greater than one are often published... Steve
However, some testers "hide" or mask, the edges of the test piece during the tests so as not to add extra absorption during the test - without this, it is possible for the test to return values of greater than one at some frequencies. Some manufacturers simply quote these values as measured, so we end up with absorption figures in some ranges of, say, 1.12 - It's not that this is really bogus, it's just not consistent unless EVERYONE does the test the same way. For example, you can get more useful absorption out of the exact same square footage of material, simply by cutting it into smaller pieces so that there is more edge surface exposed to the sound field - kind of "free" absorption, so to speak.
Some manufacturers state very plainly how their tests are done; things like distance of the material from the boundary wall, whether or not the edges were masked for the test, etc - generally, though, any time you see values in excess of 1.00 you can assume that the edges were NOT masked. YOu can NOT, however, assume that the rest of the test was done right without the proper test methods being stipulated.
These tests are a lot more complex than I've just covered (partly because I don't know all that's done in them yet myself), but that's generally why numbers greater than one are often published... Steve
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Eric_Desart
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R is used in Europe too:Innovations wrote:In the US lambda is called the R value. It is a measure of the thermal transmission."
It's not really transmission but Resistance (where the R comes from)
It's the reverse of the Lambda value taking the thickness of the material into account:
The material thickness divided by the Lambda value.
So: The lower the Lambda value or the larger the thickness the higher the R value.
The R value allows to calculate the total isolation by summing the different parts of a combination of materials.
Best regards - Eric Desart
My posts are never meant to sell whatever incl. myself, neither direct, nor indirect.
My posts are never meant to sell whatever incl. myself, neither direct, nor indirect.
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ponkass
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knightfly
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Andy, the correction wasn't because I thought you needed it; I just don't want to leave misconceptions to spread where I'm aware of more correct information.
Spelling - here is what the dictionary has -
ab·sorp·tion (…b-sôrp“sh…n, -zôrp“-) n. 1. The act or process of absorbing or the condition of being absorbed. 2. A state of mental concentration. [Latin absorpti½, absorpti½n-, from absorptus, past participle of absorb¶re, to absorb. See ABSORB.] --ab·sorp“tive (-t¹v) adj. --ab”sorp·tiv“i·ty n.
I never cease to be amazed at the number of exceptions in the english language - it seems silly to me to change "absorb" to "absorp" just to add a suffix, but there it is
I don't try to correct others' spelling, but I do re-read every post I write to make sure I've said what I actually meant - it seems to minimise confusion somewhat, which cuts down on the number of explanations I need to go through so that people get what they need -
Hopefully the bottom line is that everyone goes away LESS confused, not MORE - if ever that's NOT the case, I would hope you keep at it til you're satisfied... Steve
Spelling - here is what the dictionary has -
ab·sorp·tion (…b-sôrp“sh…n, -zôrp“-) n. 1. The act or process of absorbing or the condition of being absorbed. 2. A state of mental concentration. [Latin absorpti½, absorpti½n-, from absorptus, past participle of absorb¶re, to absorb. See ABSORB.] --ab·sorp“tive (-t¹v) adj. --ab”sorp·tiv“i·ty n.
I never cease to be amazed at the number of exceptions in the english language - it seems silly to me to change "absorb" to "absorp" just to add a suffix, but there it is
I don't try to correct others' spelling, but I do re-read every post I write to make sure I've said what I actually meant - it seems to minimise confusion somewhat, which cuts down on the number of explanations I need to go through so that people get what they need -
Hopefully the bottom line is that everyone goes away LESS confused, not MORE
- if ever that's NOT the case, I would hope you keep at it til you're satisfied... Steve-
ponkass
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hehe.. dictionaries are cool.. maybe i should try one sometimes...=)
Thanks to you Steve, and John and all the other helpers on this forum i always go away less confused (but probably with more questions =)..) after each visit to this great forum, and you can bet your most valuable microphone that i kepp at it until i´m satisfied...
...
Thanks again for your time...
Andy
Thanks to you Steve, and John and all the other helpers on this forum i always go away less confused (but probably with more questions =)..) after each visit to this great forum, and you can bet your most valuable microphone that i kepp at it until i´m satisfied...
... Thanks again for your time...
Andy
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knightfly
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Which is one of my favorite pastimes. 
