Can Fiberglass Work if Done Properly?
bk24
| Posted in Energy, Heating & Insulation on
I know that most of the folks in this forum dislike the use of fiberglass because it does not maintain its R-value in leaky wall cavities due to air washing. My question is: if a wall cavity was completely sealed – as in the sheathing was caulked or glued to the framing and the sheetrock was glued to the framing during installation – would fiberglass work ok? If so, does it make sense to dense pack? I know that R-19 (5.5 inch) does not keep it’s full R-value if compressed into a 3.5 inch space, but does it do better than standard R-13 (3.5 inch)?
Edited 5/4/2008 2:23 am ET by bk24
Edited 5/4/2008 2:24 am ET by bk24
Replies
Bk24,
Q. "I know that R-19 (5.5 inch) does not keep its full R-value if compressed into a 3.5 inch space, but does it do better than standard R-13 (3.5 inch)?"
A. Yes. Compressing a 5.5 inch batt to 3.5 inches will reduce the R-value compared to the same batt installed in a 5.5 inch cavity, but will increase the R-value per inch compared to a 3.5 inch batt installed in a 3.5 inch cavity.
In other words, fiberglass manufacturers have not optimized the density or the R-value per inch of their product. They sell a fluffier-than-optimum product in order to reduce the cost of manufacture. If you are willing to buy the 5.5 inch batt and compress it, your 3.5 inch cavity will have a higher R-value than if it were filled with a 3.5 inch thick batt.
Edited 5/4/2008 6:45 am ET by MartinHolladay
But the wall R-value will be less than the rated R-19 of the 5.5"....right?
And what would the compressed 5.5" R-rating be?
Is there a quotable source for this discussion's kind of info?
Sure would be nice to have to lay in front of a client during a discussions of energy efficiency versus cost effectiveness.
...............Iron Helix
An R-19 compressed to 3.5" will likely be better than the HD R-13, but we really don't know what it might be. Two R-19 in a 6" wall will not be R-38, but it will be a lot more than an R-19.
Will a fiberglass batt give you an R-19? Installed properly and w/ proper construction, I think the answer is yes. Given a properly constructed wall cavity, I feel there is limited opportunity for air wash. Fiberglass should be installed w/out any cavities/voids (due to piping, wiring, over/under stuffing, obstructions, and other irregularities). Insulating, as such, is a skill like any other trade. Unfortunately it is often done by some of the lesser skilled tradesmen.
I had a guy tell me that wet blown cellulose doesn't pass air like fiberglass. I believe him. ... but his demo of actually forcing air through a fiberglass sample is not a reasonable reflection of what happens in real construction.
There is a time and place for everything and everything has its advanatages and disadvantages. Pay your $ and take your choice. I advocate informed decisions ... almost all involve some degree of compromise.
In all means & methods....the devil is in the details!!!!!!
....Iron Helix
"Two R-19 in a 6" wall will not be R-38, but it will be a lot more than an R-19."Not quite. there is a point of diminishing returns where because you are substituting solid glass instead of containing dead air in place, you increase the conductive heat loss. I read an article based on a study of this back in the mid seventies. I forget ate wat point exactly, but recall that for practical purposes, you can only increase the batt density 30-50 percent. Your example goes to 100%, where the R-value might actually be R-18
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I'm not an expert, but I do have a good sense about this. High density fiberglass is frequently made for all kinds of applications with an R-value per inch that is higher than standard batts (3.1/inch). And those applications result in MUCH higher densities than 2 R-19 batts in a 5.5 inch wall.
My guess is that maybe the diminishing benefit isn't a linear function. I'm confident that 2 R-19 batts in a 6" wall will be significantly higher than an R-19, not worse. No offense intended, but I'd reread that article again to get the sailient points correct. If you do find it ... share it ... love to see what it does say. Some blind leading the blind hear ... and for that I apologize for maybe stepping into the conversation too far.
I doubt that I'll ever see an article I read in the seventies again, LOLAnd my instinct is in line with what you just said. I doubt very much that two crammed would be worth less, but there could be spots where that is so.What is the R-value of the woven panel FG for ducting anyways? That would probably indicate the upper end.BTW, ref previous post of yours, BIBs stands for Blown in Blanket, a trademark for chopped FG, not for DensPak Cellulose blown in. bIBs is a bit higher than Cells i cost.
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What is the advantage (if any) of wet blown cellulose over denspak BIB cellulose? How do they compare in R-value and cost? I have also been told that wet blown cellulose becomes part of the structure and gives greater structural rigidity. Hard for me to believe, but any truth to this?Also, is it true that in wet humid areas that wet blown cellulose is at risk for mold?
"I have also been told that wet blown cellulose becomes part of the structure and gives greater structural rigidity. Hard for me to believe, but any truth to this?"Maybe it's done differently in other areas, but I can assure you 100% that the wet blown cellulose in this area does not add ANY structural strength to the wall system.I have heard that was the case with closed cell foam. In fact, I read a study (I think in "Coastal Contractor" by Hanley Wood) that the foam industry was pushing to get foam blown against the roof sheathing and rafters/trusses as being just as strong as doubling the nailing schedule on the roof sheathing.
Jon Blakemore RappahannockINC.com Fredericksburg, VA
Wet blown is a mold risk anyplace if they do not let it dry before covering it up.
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So you have to wait for it to dry and lost site time. Why do it? Is there some advantage over denspack cellulose? I don't get it.
I never did either.. Maybe somebody else can take up for it with more info. There would be some labour savings in that you might not need to spend time stapling up the containment mesh
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Not sure of the differences in wet blown vs. BIB. Very similar results, though as far as R-value and filling voids. have no idea about cost comparisons. My guess is that the BIB may be a bit more, but I've really no feel for it.
I'd be skeptical re: increase in structural rigidity. I'm sure it does, but I'm sure it is negligible and unpredictable.
In humid areas ... may be tough ... you need to be able to dry it out. May have to A/C the space a lot to wring out the air to ensure that it does dry out before e.g. sheetrock is applied. An installer should be able to give you a better sense of what needs to be done in humid climates. Misapplied, it can definately be an issue!! Remember, drywall mud is much the same ... lots of moisture to get rid of (although not buried under 6" of insulation)!
http://saveenergy.owenscorningblog.com/2006/11/Question: What insulation should I use in my cathedral ceiling?
Clint writes from Catoosa, Oklahoma: "I have a 2'x8' cathedral ceiling (new construction) that I am trying to insulate. I have already put in nailers and screwed polyisocyanurate aluminum-faced foam board up inside the rafter cavity. With the foam board in place I only have a 5" space left to fill with fiberglass insulation. I was wondering what would be the best thing to do, I can put in R-19 6.25" thick or R-21 5.5" thick. I know either way I will be compressing the insulation which is undesirable. How much R-value loss could I expect if I compressed either of these insulation products into the 5" space?" Answer: I suggest using the R-21 in order to get the most R-value in the cavity since you only get one chance at it before the cavity is enclosed. R-19 compressed to 5 inches is probably about 16.5 where R-21 compressed to 5 inches is around 19.6.http://www.iccsafe.org/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=4;t=009647R-19 (6 1/4") fiberglass bat insulation is rated as installed in an attic insulation situation. The R- value decreases to R-18 when compressed into a 5 1/2" stud cavity and to R-13 when compressed into a 3 1/2" stud cavity. R-13 (3 1/2") bats are available as are R-15 (3 1/2") high density bats. For purposes of prescriptive code compliance, the R-values are additive so you can install R-13 in the cavity with R-5 (foam) sheathing or R-15 with R-3 (foam) sheathing and meet code for zones 5 & 6..
.
A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Thank you sir. What a Whiz kid!
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Really? I thought the value of fiberglass was really in the air. In other words, a 5.5" compressed fiberglass batt to 3.5" would have less r-value than an uncompressed 3.5" batt.
It is in the air ... but with more air pockets, you have fewer big, more inefficient pockets ... so you end up w/ a better insulation system. If if was ONLY in the air volume, leaving a cavity empty/void of any material would yield the most air space and therefore the best insulation value. It's the combination of materials and air space that provide efficiency.
Martin Holladay.
Not according to the publishers of this web site Fine Home Building issue 160. As I read the text over packing increases convextion or transfer of energy..
Solid fiberglas would have extremely poor R value, loose fill will flow air too freely.. as you get away from perfect you spend more and gain less..
There was a thread on a JLC forum on this topic a while ago in which I participated. See:
http://forums.jlconline.com/forums/showthread.php?t=35103
As I wrote then,
“In the recently published JLC book, "Tips & Techniques," on page 227, Mike Lacher answers a technical question on this topic. Mike Lacher formerly worked as a technical services manager for CertainTeed insulation. He … shares a CertainTeed chart displaying the R-values of compressed fiberglass insulation batts. The chart shows that when 12-inch thick R-38 batts are installed in a 9 1/4-inch rafter bay, the resulting R-value is R-33. This is less than the fluffed-up R-38, but it is more than the R-30 insulation that is usually sold for 2x10 rafters. Lacher writes, ‘as you compress fiberglass batt insulation, the R-value per inch goes up, but the overall R-value goes down.’â€<!----><!----><!---->
<!----> <!---->
Martin Holladay,
Thank you for that tid bit, but given that the source works for a fiberglas company I wonder if there is a bias in there?
Please understand I'm not saying there is but you must admit the potential for bias would be strong.
A better choice is to purchase high-density FG batts instead of the standard ones. But, as you say, compressing standard batts will, within limits, improve the R value per inch of the product.To answer the OP's original question, tightly air-sealing both sides of the stud cavity will greatly improve the effectiveness of fiberglass. Any sort of draft through the fiberglass significantly dimimishes its effectiveness.It would be interesting to see FG mfgrs produce a product with some sort of imbedded draft stop, such as a Tyvek barrier halfway through, or plastic draft stops embedded at right angles to the batt somehow. Of course they wouldn't want to do this even if they could since it would be admitting that the standard product is seriously deficient.
What is wanted is not the will to believe, but the will to find out, which is the exact opposite. --Bertrand Russell
The movement of air through the fg batts is certainly a problem in terms of diminished insulating values, but movement of air within the stud space may well allow the wall to dry itself.
I can understand the importance of sealing the interior surface of the wall, and understand the logic involved with recommending sealing the exterior, but in wet climates such as the PNW, when you seal both sides of the wall, you are relying on the exterior allowing no water infiltration over the life of the house. Any water that does penetrate the wall cavity can not dry to the inside or out.
Sealing both sides may work well with foam, but with fg batts I am more comfortable with the approach our code dictates of gaps and holes in the exterior sheathing, coupled with a rain screen. It's just a more forgiving system.
bk24
In Fine Home Building issue 160 (Jan 2004) they debate this subject and do a comparison of the three systems.
In the end they said,, forget the product pick the best contractor..
However if you go through the whole text they mention convection, they mention leaks, and they mention the fact that when Fiberglas is wet it has virtually no R value.
They speak of over compressing and how it hurts rather than helps the insulations R value.
Bottom line, there is no replacement for doing the job perfectly. If you cannot be absolutely sure of that, even the best system will fail you..
IMO,
Fiberglass can be an effective insulation. No it is not as good as cellulose or spray foams, but it can work.
The trick is to install it meticulously. Fill the cavities with no voids. It's as simple as that. It can be done. The problem is a lot of times the lowest guys on the totem pole install that batts.
Also, common sense suggests Martin is right: compressing a batt will result in a higher R value in a given space. Why else would a high density R21 batt have a higher R value than a low density R 19 batt?
Marson..
Because R value isn't really correct! You are aware that R value is tested at 70 degrees aren't you? Not at zero or 40 below where the performance of fiberglas is severely compromised.. Quote, "by up to 50% at 40 below"
Fine Home Building # 160 Jan 2004 page 52
In addition it's tested under controlled labrotory conditions where there is no humidity in the air or wind blowing..
All of which affect fiberglas most of all of the three comm on types of insulation.
Whoa, all I said is that fiberglass can be an effective insulation if installed properly. The way it is maligned on this board you'd think you might as well not use it--just go with uninsulated stud cavities. That's preposterous. No, it isn't as good as other systems. But it has it's place. Yes it does work. It actually reduces heat flow.Every single decision in this business is a trade off between what is optimal and what is affordable. Sometimes those lower cost options make sense.
Edited 5/4/2008 8:30 pm ET by Marson
Marson,
Please let's not go to extremes. I do agree some insulation is better than no insulation.
However as has been pointed out the price differance is nil between between celuliose and fiberglas, yes there is a small premium for spray foam but if we step back and look hard at alternatives SIP's and ICF's can become affordable..
Oil is now 116 a barrel in the next decade that can easily double if not more!
If you want to build affordable homes you have to start calculating in the cost of heating. I'll grant that used to be chump change.. Not anymore! Heating will quickly assume the importance of payments!
Well Frenchy, I don't mean to start a war. I agree with you that money spent on insulation is money well spent, given where heating oil is headed.But I have to disagree about your assertion that the price difference between fiberglass and cellulose is nil. Perhaps you are in a diffent market than I am, or maybe you are aware of some techniques that I don't know about. Cellulose may have a similar material cost, but the mesh used for blowing walls is not easily available. Nor do I have access to a blower capable of blowing it at the required density for walls. That leaves hiring an insulation contractor, and believe me, the difference in price between cellulose and fiberglass is not nil. Spray foam is more expensive yet.
Marson
I certainly don't feel that we are at war, merely two people expressing differances over pricing. I'll gladly shake your hand even if we wind up in total disagreement..
As to the pricing between installed fiberglas and installed celluliose I've seen enough bids and heard it refered to by enough posters on this site to accept it as fact.
If you are comparing DIY with any proffesional installation we're clearly talking apples and oranges..
Again refering to professionally installed foam versis professionally installed fiberglas/celluliose In general I'm seeing a 10% to as high as 15% differnace in pricing..
If you've watched the process, all three take approximately the same time labor wise, all three typically are done with three man crews, and material costs are not wildly differant at the wholesale level.. The only differance is that fiberglass batts have a slight advantage in that no expensive equipment is required to put them in..
Thus clearly the potential for greater profit is with foam.. It's percieved as a superior product so a premium is commanded..
The disadvantage of fiberglas is too well documented to be a serious question with Foam having a clear advantage over either fiberglas or celluliose.
"Again refering to professionally installed foam versis professionally installed fiberglas/celluliose In general I'm seeing a 10% to as high as 15% differnace in pricing.."Frenchy,If I'm understanding what you wrote above, that foam costs at most 15% more than fiberglass or cellulose, I will have to vehemently disagree.In our area, you would pay about 2.5x more for closed cell spray foam vs. cellulose. FG would save you even more over cellulose. This is assuming you insulate to a comparable R value (FG and cellulose at roughly R3.5/inch, and SPF at R6.5/inch).If spray foam was 10% more than FG, I think we would use foam exclusively.
Jon Blakemore RappahannockINC.com Fredericksburg, VA
Jon,
There are all sorts of factors which can cause that.. how much competition is there between various foam installers? Here there's a great deal and they cut each others throat for a quarter.. 10 cents if you provide the knife <grin>
I pointed out that in a typical house you will see the insulation truck there about the same period of time no matter what is being done.. most crews I see are three man crews and if you check on the wholesale costs of the material of the 3 insulations they aren't dramatically differant..
My brother-in-law paid above the going rate for his foam job thinking he was getting the guy's good reputation. (he didn't, the business was sold) so he could have had his job done for the margin I mentioned. MY neighbor had similar bids for foam or celluliose. However he paid $500 a trip set-up charge and it came out about 15% higher after 3 trips..
In a 10 mile radius I know of 4 foam crews so maybe they are more hungary here with the loss of any new home construction and only minimal remodeling..
Now to be fair these numbers are conversation only. I've not seen bids. I do know that when I asked about doing a little job the next time he was there the neighbors foam guy gave me budget numbers that represented a total setup charge even when he was right next door. Plus a mileage charge. I had menatally estimated $1000 and he was well over that. at $1400.. Without the setup charge and mileage he would have been around $100 less than my mental budget.. I did it myself for less than $300.00 but it took me more than a week rather than less than an hour.
Are you sure they're spraying a comparable R value?I've had foam insulation guys say that you don't really need R13 or R19 in your walls, that their foam performs just as well at R9 and that's all you need. While I fully appreciate the benefit of the air sealing that the foam offers, I still want to insulate to a code-prescribed level.If foam was competitive with the other types, who would use fiberglass?
Jon Blakemore RappahannockINC.com Fredericksburg, VA
Jon,
I sure agree with that statement, if Foam were priced with fiberglas who would use fiberglas..
I'm sure when they fill the stud bay with foam it's as high an R value as you can get.. I probably also mispoke earlier because some foams are more expensive than others.. The foam normally used is called EPS, however I've seen Polyisocynanurate quoted as well as several other foams, some of which really elaborate claims of R values are made..
Most EPS foams (coffee cup foam) have R values of 3.6 per inch while the better foams have a R Value of 7 per inch. I have seen something that looks like Dow's ridgid blue board when sprayed claim 30 per inch with literature backing it up but I have a hard time accepting that..
One other bit in the article in Fine home building they say that sprayed foam should cost 15 cents per sq.ft. per inch That's 82 1/2 cents per square foot for 2x6 construction (page 54) Yet they talk about installed fiberglas batts as being up to $2.50 a sq.ft. per R value.. (page 50)
That clearly doesn't seem right..
Frenchy,Just to clarify, we are talking about spray foam vs. rigid foam board, correct?Your comments about EPS, XPS, and polyiso make me think we not on the same page."One other bit in the article in Fine home building they say that sprayed foam should cost 15 cents per sq.ft. per inch That's 82 1/2 cents per square foot for 2x6 construction (page 54)"I pulled issue #160 out and I don't think you're interpreting the costs correctly. They say that rigid EPS (expanded polystyrene) typically costs $.15 per board foot. To my knowledge, you cannot "spray" EPS in a wall cavity. Surely some are using EPS as insulation, but they would be installing it by cutting pieces at 14-1/2"x92-5/8" or similar sizes and installing those pieces in the stud bay."Yet they talk about installed fiberglas batts as being up to $2.50 a sq.ft. per R value.. (page 50)"Again, they're saying that the price range for the different types of insulation (batts, blown-in, sprayed form, and rigid foam panels) can vary greatly. Which is what I've been trying to say (SPF vs. batts cost differences).
Jon Blakemore RappahannockINC.com Fredericksburg, VA
Jon
Good points all of them Jon, however Most SIP's are EPS at least the R numbers align with EPS, it looks like EPS as is the sprayed foam I see in most homes.. (yes of course I also see exceptions but they tend to be more expensive and thus less common) When the factory I buy my panels from sells sheets of them they look the same.
I've called it coffee cup foam because I'm not a chemist.. There may be differances but I'm really not aware of them.
Frenchy,You're right that most SIPs are EPS, as well as most foam coffee cups, but SIPs and rigid foam boards are not really germane to this conversation.
Jon Blakemore RappahannockINC.com Fredericksburg, VA
Sips are not made by spraying foam.They use EPS and then laminate the OSB, DW or whatever to it.I was in a factory where they made the foam and the SIPS. I did not see any SIPS in the area that I went through.But they have billets of EPS. It has been a while so I don't remember the exact numbers, maybe 12 ft, by 8 by 4. Then they sawed that into sheets as they needed..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
BillHartmann,
And your point is? I went into length describing what the factory did building panels. Do you need a step by step description? want me to explain how the adhesive is applied and how much pressure they use in the bonding process? Want to discuss tempuratures and sizes avaliable or more interesting how they core the foam for wire chases?
It's still coffee cup foam to me..
The point is that SIPS does not use a sprayed in foam.Much different chemcially and functionally to foam that is sprayed in wall cavities..
.
A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Show me a company that sprays styrofoam in walls..
.
A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Around my neck of the woods:
Blown in Blanket FG is $1.00/sq. ft. (5.5" thick, R-22-ish)
Blown Cellulose is $0.95/sq. ft. (5.5" thick, R-20-ish)
Icynene Spray Foam is $2.00/sq. ft. (5.5" thick, R-20-ish)
Closed Cell Spray Foam is $3.50/ sq. ft. (3.5" thick, R-23-ish)
Don't know installed cost of FG Batts.
Doobz26
Thanks those are among the first real numbers I've seen. How do the foam installers stand compared to the celluliose and fiberglass guys? Competition wise? same number of each ? Around here like I said they are cutting each others throat, I can't say that they are using smart business practices because so many are soooooooooo hungary. There are actaully more foam installers than celluliose. I know of only one installer who does blown in celluliose and there are 4 right around here doing foam..
I forgot to mention there is a four to five hundred charge by both foam companies just to show up on site. Around here I am only aware of one BIBB guy, one cellulose guy, one Icynene guy and one closed cell poly guy. Both foam guys are over an hours commute away. So they are all kind of competing against each others product.
Doobz26
Yeh, four years ago that was rigidly adhered to,, three years ago you could sometimes get that waived on larger jobs . Today the only guy who hasn't waved it lately has his business up for sale.. (at least there was a for sale sign on the trailer he used)
It will vary from two to three times as expensive here.
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I have worked for an affordable housing non-profit that had an owner built housing program(sweat equity kind of thing -- and no it wasn't Habitat). We participated in an energy efficiency program that was contingent upon proper air sealing and fiberglass insulation installation and properly sized, installed and sealed HVAC equipment. Our homeowners(all amatuers) were trained to install the insulation in everybody's homes and air seal in the proper way and then they were inspected by the agency administering the program(no -- most building inspectors are not enforcing proper fiberglass insulation installation). At the end of construction blower door tests and duct blaster tests were performed and assuming the homes passed the energy agency gauranteed heating and cooling costs of between $25-30 a month(all electric heat pumps -- approx. 1200 sq. ft of heated living space). All the homes passed their 3rd party insulation inspections with flying colors and their blower door tests. The key as mentioned is to fill all voids, no compression and one thing not mentioned is that the surface of the insulation should be in full contact with exterior sheathing and the back of the drywall to prevent convection in the wall cavities.
All of the homes were insulated by DIY homeowners, once they learned the proper way to install fiberglass they did a beautiful job. Anybody can do it and best of all the material is still the cheapest thing going. You could pay a little more for labor so that they get it right and still come out on top. Most building science/energy efficiency non-profits should have demonstration videos or trainings that show the right way. The one mentioned above is in NC and is called Advanced Energy. Google them.
One of the main problems with FG batts is not due to air moving through the stud cavity, but from air moving within the cavity.
Air at the outside surface cools and sinks, moviong through the fibres.
t the same time, air nearest the inside wall surface gets heated and rises thru the FG fibres. A gradual convection loop is set up then as that air then reaches the top plate and begins to move down the outside wall as it cools.
The resulting convection loop is then working to slowly transfer heat energy to the exterior of the assembly. The greater the temperature differential between exterior and interior surfaces, the faster the loop operates.
it is unfortunate that R-values are measured and officially recorded with a differential of only ten degrees ( 60°F exterior to 70°F interior ) because independent tests show a far lower value for batts with a greater differential.
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Taunton University of Knowledge FHB Campus at Breaktime.
where ...
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PIffin,
Wow we're in total agreement!
Life gets scary sometimes
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C'Mon Piffin. That was has proved to be a myth. Convection through FG insulation properly in stud cavities is an false claim based on the findings about convection in loose fill attic insulation. I wish I had bookmarked the test result on it . I guess I am in for a lot of time spent googleing foam insulators websites to find the proof again.
They can't get your Goat if you don't tell them where it is hidden.
maybe to you, but I haven't seen it. The closest anything has come to disproving it in what I've read is some bits that cast doubt on the studies I did post, most of which had to do with attic loose fill and nothing to do with stud cavities. There is plenty showing that the R-value of a wall assembly drops with greater temperature differential with FG batts but far less so with any other insulation, Spray polyurethene foam performing best of all.
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I am only disputing the convection loop though the FG . Not disputing the R-value degradation . nor the effectiveness of the foam. I will search again for the test results. Give some time , it took several nights last time to follow one link to the next until I found the comments .
They can't get your Goat if you don't tell them where it is hidden.
The convection loop is the reason for the loss of R-value at lower temps. Degradation refers to the loss of R-value over time and it occours in all types of insulation.
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I haven't been real impressed with spray foam. Those guys are making money hand over fist (My wife is an accountant and does the books for a local foam contractor). We had some rim joists sprayed on a 15oo sf house, and it was 2500 bucks. I could have insulated the whole house with fiberglass for that. And in spite of enduring multiple sales pitches by the foam guys, when we have used it, I have not been at all impressed by the consistency. Some spots look like they are a foot thick, but others are less than 3. I saw foam sprayed into walls on This Old House some years ago, and they filled the stud cavities full and then sawed of the foam flush with the studs. I don't see that being done around here. (I bet it creates hell for the sheetrockers.) Anyone else see that?Yeah, yeah, I know it is great for air sealing and has a great r value per inch. Personally, I'd go with dense pack cellulose if it was my own house.
Marson.
I absolutely agree that some foam installers are charging too much.. that's why we get such inconsitant numbers.. It's the like question is here's cost now how much money do we want to make?
Here where people are hanging on for dear life and such games can't be played prices are far more reasonable..
Don't be fooled, foam is better than other insulation.. toss a little real world into those lab test results and see which insulation holds the strongest values!
Thanks, the first two links may provide a pathway for me to find what I previously posted. Notice that several of the others refer to J.D. Nillsan (sp?) quote . That is the cherry picked information. It refers to only LOOSE filled, not batt. I am not arguing R-value claims. I am only stating that there was a test done that disproved the commonly stated as fact statement that convection loops occur THOUGH FG batt insulation when it is properly installed.
I believe it was Oak ridge testing and the testers were actually surprised at the results because they expected to see just what the false claim states. If I am wrong in what I am saying I will quite cheerfully say so. Give me some time to track the issue please. What is strange to me right now is I remember the thread that I posted it in and after I posted it and several others read it they agreed with me. Oak ridge discovered that covering the loose fill insulation with several inches of cellulose cured the problem. I thought you were one of them.
They can't get your Goat if you don't tell them where it is hidden.
dovetail
I think I remember reading such a test.. how they proved it doesn't exist.. I also remember something reasonably credable that discredited their tests..
Most of may sources are in stacks of magazines so please be tolerant while I find them if I can..
Rather than get all hot and bothered with Riversong, I bowed out early because he would get as irrational as frenchy.I do recall an earlier - maybe a year ago - discussion with you that was illuminating for both of us, but don't recall it ever reaching a conclusion.It is the studies on loose fill in attics that challenged some of my thinking, but I have never seen anything like evidence that convection loops do not rob heat in stud cavities.The phenomenon is so well documented that I was stumbling across dozens of articles dealing with it in double pane window design, and mechanical engineering having to deal with it in liquids. Segregating just the links that pertained to walls was quite a job.
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Here is a google search of the J.D. Nisson article. Notice how every single one of the references that actually quotes the article has the phase " Loose filled attic insulation" That is the one Oak Ridge test. I am looking for the other. Patience please. http://www.google.com/search?q=+Nisson%2C+J.D.+Ned%2C+JLC%2C+%E2%80%9CAttic+Insulation+Problems+In+Cold+Climates%E2%80%9D&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-####
They can't get your Goat if you don't tell them where it is hidden.
The closest I have come to an actual reporting of the test so far. This one does not mention the cellulose top coat over the loose fill. http://www.homeenergy.org/archive/hem.dis.anl.gov/eehem/92/920510.html
They can't get your Goat if you don't tell them where it is hidden.
Long down load . Good read, lots of data.
Real life winter test. Those interested may want to start about page 263 and skim though at least pg. 280. Page 273 has the chart that shows comparative results for the testing of 4 attic bays , two with FG Batts and two with FG loose fill. There is a chart there that shows final tested R-values. All bays started out with R-30 , although they actually tested the insulation prior to installing it and found it to be slightly less than that . Final result : Read it for yourself. Batts hit R-29 over the duration of the test. (No that is not a MISPRINT) Short version is that there was negligible convection currents within BATT FG insulation. http://books.google.com/books?id=miXWZMuRE_8C&pg=PA276&lpg=PA276&dq=Attic+Testing+at+the+Roof+Research+Center&source=web&ots=uyUpqymcBh&sig=CiE9ujPe2RtI8W5oDs2pz-BQo4w&hl=en#PPA273,M1
They can't get your Goat if you don't tell them where it is hidden.
Here's is another interesting test with results. Cellulose vs. fiberglass loose fill (blown) http://www.gwscientific.com/cchrc/rtf_data/roof/roof_fig1.html
Edited 5/5/2008 10:32 pm by dovetail97128
Swedish study and analysis. For those interested in doing research there is a whole list of references at the end of this one. Including what I think is the original Oak Ridge test. http://www.byv.kth.se/avd/byte/reykjavik/pdf/art_085.pdf Ok break time. When I get back I will start on the actual wall cavity issue.
They can't get your Goat if you don't tell them where it is hidden.
Ok , This does not address Convection through the FG batts, but was interesting to me. Here is one test done to compare using this product:
http://p2000insulation.ca/news/index.php
In conjunction with R-19 batts in a wall cavity and just R-19 batts alone. Interesting results. http://p2000insulation.ca/testing/pdf/ASTM%20C%201363-05%20Test%20Report.pdf
They can't get your Goat if you don't tell them where it is hidden.
BINGO!! Results of the Oak Ridge test I remember seeing. http://www.celbar.com/pdf/energystudy.pdf Page 3. Also reported here: http://arkansasedc.com/Business_Development/energy/files/Clearinghouse/Thermal%20Shorts.pdf
Please remember that I was only contesting the statement concerning convection currents and nothing else.
Edited 5/6/2008 1:29 am by dovetail97128
Found this as well:http://www.ornl.gov/sci/roofs+walls/AWT/HotboxTest/LennarWood/results.htm This is the site : http://www.ornl.gov/sci/roofs+walls/AWT/Ref/wood.htm This was the lead in link:
http://www.ornl.gov/sci/roofs+walls/AWT/Ref/TechHome.htm This led to the previous link:http://www.ornl.gov/sci/roofs+walls/AWT/InteractiveCalculators/rvalueinfo.htmAn FG R-13 batt , 2 x 4 wall tested out at a total air to air measurement of R=10.94 and 10.81
They can't get your Goat if you don't tell them where it is hidden.
dovetail
What temps were those tests conducted at? What level of humidity and What air movement (wind)?
Another words were those real word tests or lab tests?
Frenchy, Read the tests for yourself. I provided plenty of info. Now if You want to find something that proves the existence of convective loops THROUGH FG batt insulation that was properly installed in wall cavities I am more than happy to be proven wrong here. This is about correcting an oft repeated cherry picked piece of information from a test that wasn't meant to even test the phenomena.
The whole deal about the loss of R-value in FG when delta "T" is severe is from the one test in attics using LOSE FILL FG.. I am only trying to get you to quit repeating inaccurate and unsupported information that is nothing but marketing claims by other insulation manufacturers. Honestly I am simply trying to correct the misinformation , not prove anyone to be personally wrong.
They can't get your Goat if you don't tell them where it is hidden.
I found the testing of the P2000 interesting. It shows that you can basically get about R11 out of it. A far cry from the outlandish claims they used to make. What is that stuff? foil-faced EPS?Steve
http://www.p2insulation.com/flashfiles/index.html Looks like foil faced EPS 1/2" thick .
They can't get your Goat if you don't tell them where it is hidden.
"I found the testing of the P2000 interesting. It shows that you can basically get about R11 out of it."Not exactly.You only end up with an 10.2 assembly. But one without any insulation is 2.2So only 8 is gained using this.And if the core is 1" EPS that would have an R value of about 4.And that is applied over the whole frame so that it reduces thermobriding. I have to do more work that I to do, but my SPECULATION is that equivalent to R 2.IE, a similar test using bare faced 1" EPS would show an assembly test of about R-8.So the radiant barrier foil only adds about 2 points.Note - R value is only defined for a product. But is not applicable for radiant barriers.For other types of insulation you can add them up to get an assembly rating. But for radiant barrier the best comparison is testing as an assembly. So some of my comparisons are not 100% accurate, but I think reasonably for this case..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
You're right. I was quoting the number from memory. What I took away from it was that it was not worth the effort for performance that was no better than anything else. I didn't see it on the web site now, but If I recall they used to claim outrageously high R-values. I think they were banned from advertising them as such in certain states at one point. In any event, it points to the worthlessness of marketing hype.Steve
There was a one of the "bubble pack" with metalic coating one or both sides that has advertising problems.I though that had a "2000" in the name..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Our Tahoe house was insulated with different systems in series. Under the stucco was 1/4" Greenguard drainage channel foam sheets. The whole house was shear paneled. 2x6 walls mostly (some 3x6). The cavities were first sealed with a thin layer of Tigerfoam. Then conventional code minimum fiberglass. The house is really warm on even the coldest days.
Costs: Greenguard - I'm not sure but the stucco guys papered anyhow so the projected savings of replacing paper or tyvek with the greenguard did not happen(who knows if moisture damage prevention benefits will ever occur for me from the Greenguard). Also I went through a bit of the winter with only the Greenguard and it was COLD!
Shear panel - well we needed that almost everywhere for seismic loads so that huge expense doesn't really count.
Tigerfoam- about 2k and they did the whole house in a day or two with one guy.
Insulation - 7k bid out.
The house is 3500' with another 1500' of garages. The difference between the comfort level of the old house (or the uninsulated house) and the modern insulation is huge. The level in the porpane tank went up after the drywallers finished! OK I checked it first on a cold day and rechecked on a warm day but no matter what, it is not using much energy to keep warm inside - even on the really cold snowy days.
When wiring plugs. I can feel a slight cold draft coming out of the boxes. So the fiberglass is allowing some air movement. But it is a small heat loss and once the coverplates are on I can't feel anything. I doubt that it is a huge reduction in R value.
From the feel of the house, the mixed insulation types works really well. I may have wasted some money on the Greenguard and tigerfoam as it was the conventional fiberglass insulation that really changed the comfort level inside. Perhaps 90% of the heat loss is stopped by fiberglass. Making a dent in the last 10% gets exponentially more expensive and doesn't make too much sense financially. I made too many choices like this and blew the budget. Hopefully we can finish it out OK with the new financial situation.
Eric
eric,
Can you stick a foam straw into the back of the electrical cases? If so you could seal them off with a simple can of great stuff. Please wear disposable gloves though.. if you get the foam on your skin the only way to get it off is to wear it off (takes about a week <grin>
Thanks for the feedback!
The amount of cold air is very small. I was just weighing in on the fiberglass air movement discussion, not worrying about getting cooler from that heat loss. And my point may have been lost; the air movement in the fiberglass insulated wall is measurable but trivial. Putting the coverplates on the plugs made it so I couldn't feel any air movement at all. If I sealed each box, I would never pay off the can of foam (or my time) regardless of the price of energy.
Overall, I am very happy with my fiberglass insulation. It works well in a fairly severe environment. Of course the Greenguard and the Tigerfoam contribute to how well the entire insulation works. If we leave the door open for a minute or two, that cools the house more than the heat loss through the walls all day.
Eric
frenchy, hand lotion works on removingit.
In the ongoing debate about about insulation efficiency and value, occasionally it is helpful to have updated pricing (which, I am told has dropped substantially in the last few months) to set in place some data points.This is in Seattle. Prices are bound to be different around the country. There may be better deals around here for all I know, but this seems like pretty competitive pricing to me. I got this from Burnham Insulation (425.881.2666). The young guy I spoke with, Jason Stephenson was really knowledgeable and used the 2" of UCCF + 3.5" of CL BIBS on his own house and thinks that is the best combination of price and performance. The foam seals the cavity adds a lot of structural strength to the structure while the CL is affordable and great for soundproofing.FG= fiberglass
CL= cellulose
BIBS= blown in blanket system
UCCF= urethane closed cell foamWall SystemR21 FG HD Batt 5.5 inch .47/sfR21 FG BIBS 5.5 inch .97 /sfR21 CL BIBS 5.5 inch .75 /sfR21 UCCF 3.5 inch 2.19/sfR23 UCCF 2.0 inch 1.82/sf
+3.5 R11 FG Batt R26 UCCF 2.0 inch 2.08/sf
+3.5 CL BIBSR27 UCCF 2.0 inch 2.07/sf
+3.5 R15 FGHD BattR30 UCCF 5.0 inch 3.21/sfR26 7" CL BIBs .97/sf
(for 6+2 Mooney Wall Attic SystemR38 FG attic Batt .84/sfR49 13" blown CL attic .55/sfR60 18" blown CL attic .66/sf
dovetail.
I do recall reading a credible source that provided me with evidence of their existance. Not a theory or pretty pictures but more of a mathmatical calculation based on side by side condition. However I seldom wander away from this site on the computer.. I am a books and magazine guy. Thus I won't be able to provide you with a link.. I will give you the number etc. of the magazine or library of congress number plus enough information for you to find it..
It will take me a while to find the article I mentioned.. I can't remember for sure.. My library which used to be on shelves is up in the attic now during construction on this part of the house.. Some tolerance is required if you honestly want to know. You can go ahead and claim victory if you need to.
Hey did you try through the test done in Alaska? I think that is where I saw it , I'm also having a hard time locateing.
I posted some links to that in the last 6 months. Using advanced search on my posts should find it..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
http://coloradohomeenergypros.com/insulationinformation.aspxhttp://www.warmtechsolutions.com/effectivervalue/http://64.233.169.104/search?q=cache:9DnyeqvmdrUJ:www.ultraseal.us/Products/PRINCIPLES_OF_HEAT_TRANSFER.pdf+wall+cavity+%2B+heat+loss+%2B+convection+loop&hl=en&ct=clnk&cd=14&gl=us&lr=lang_en&client=firefox-ahttp://www.astm.org/DIGITAL_LIBRARY/STP/PAGES/STP23320S.htmhttp://www.masterfoamwi.com/pdf/OakRidge.pdfhttp://www.masterfoamwi.com/pdf/R-value%20diminising%20return.pdf http://www.masterfoamwi.com/pdf/R-value%20Myth.pdf
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Edited 5/5/2008 8:41 pm ET by Piffin
RE.: The Colorado home study: Colorado Study (1990)For this study,7 two test buildings were constructed on the University's campus. Walls in building "A" were insulated with 5-1/2 inches of wet-spray cellulose; and walls in Building "B" were insulated with R-19 fiber glass batts.An independent review of the study by David Yarbrough Ph.D., PE of R&D Services, Inc., Lenoir City, TN, a long-time insulation researcher with Tennessee Technological University and Oak Ridge National Laboratory, states that the facts do not support the conclusion that cellulose insulation limited the air leakage in a building.Yarbrough states that he sees major deficiencies in the study. He says that "Comparative studies...must characterize the structures used and the materials used in order to eliminate the possibility that differences observed are the result of construction or mismatch of the thermal values of installed insulation. Specification of nominal insulation R-values is not sufficient for a serious thermal study."He adds that the Colorado study "illustrates the difficulties associated with large-scale thermal studies."The report reveals that blower door tests were conducted with no wallboard on the walls. Wallboard is a critical element for reducing air infiltration.In addition, the testing did not isolate the effects of floor tightness, window tightness and door seals. Therefore, it is likely that some or all of the difference in air infiltration could be attributed to these sources. There is no data to prove that these factors were even considered.From an energy standpoint, the study concludes the building insulated with cellulose used less heating energy during the test period. However, according to Yarbrough "The reasons for the lower heating energy usage of the building insulated with cellulose cannot be identified in the study."Yarbrough suggests that the 26.4% difference in energy usage "could be explained by the difference in the insulation R-values that were used."According to Yarbrough, "[Since] the thermal resistances of insulation materials actually installed were not reported ... there is good reason to believe that the thermal resistance of the installed cellulose was greater than the thermal resistance of the installed fiber glass in both the walls and attics of the test units." Now this Yarbroughs points on R-factor are a bit dubious IMO except for the fact that it had been proved long before this test was done that FG loose fill attic insulation doesn't work well. Why did they then use it in the test and not remedy it for it's shortcomings. There is nothing here to prove that convection in the FG batts in the wall was a factor if in fact it occurs in a properly done job. No conclusive test for proof as to convective loops in stud cavities was ever even attempted in this test , "real world" conditions were a blower door test done without drywall even installed????. Anyway , enough for now , I am still convinced that convective loops THROUGH FG batts is a myth and have found Zero in the way of tests to support the claim that it exists unless initiated by outside air infiltration which is what I said to begin with . Controlling air leakage is far more important then which material is used to insulate .
They can't get your Goat if you don't tell them where it is hidden.
I agree. A quick glance at those ORNL pages you posted show very minimal differences in measured R-value for the different assemblies under conditions of no wind or vapor pressure or stack effect. I believe the critical difference is in the air-sealing. And I like systems that turn the whole wall into a monolithic air barrier--ie: spray foam or DP cells. Systems that rely on a breachable membrane (poly sheeting, air-tight drywall) are just a future failure waiting to happen. Poke a decent size whole in that membrane somewhere, and the wall probably fills up with moist air driven by pressure dynamics of the house.Steve
I was amazed when I first started looking into this how the one Oak Ridge test kept appearing on any number of web sites but there were NO details given , just someones summation. That made me suspicious of "Cherry Picking" of the information. As I said this isn't at all personal , it is about correcting misinformation ( and a short lesson for all of us in how marketing claims replacing the facts!).
They can't get your Goat if you don't tell them where it is hidden.
Interesting discussion, but.......How about just using R-15 High Density FG Batts in the 2X4 walls?
Pickings.
fiberglas when dense packed doesn't gain as much as it's rated.. under the absolute best conditions R 11 walls when filled with R15 might grade up to R 12
But you need to realise that is under labratory conditions. Fiberglas insulation is rated under perfect conditions not able to replicate in the real world..
Please read Piffins statement above.. he's right!
http://www.bondedlogic.com/documents/UltraTouchSpecSheet.pdf
Everyone looking at using batts should look at the cotton batts. They are much denser than fiberglass - they almost feel like a foam cushion. R13 for 3.5" wall, R19 for 5.5" batt. Real easy to work with.Rebuilding my home in Cypress, CA
Also a CRX fanatic!
If your hair looks funny, it's because God likes to scratch his nuts. You nut, you.
"iberglas when dense packed doesn't gain as much as it's rated.. under the absolute best conditions R 11 walls when filled with R15 might grade up to R 12"That makes absolutley no sense at all.If I put R-15 in a 2x4 wall I would expect R-15 performance from the FG portion..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
BillHartmann,
There is plenty of other sources to confirm that information.. Please be tolerant and I'll find it later for you OK? Remind me to look tomorrow if I don't.
That is the right answer if he is stuck with having to use batts
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
IMO properly installed FG batts work much better that the adherents of other insulation would have you believe.
Purchase high density batts, better then using overthick insulation..
Do whatever you can to cut down on air infiltration into the stud cavity, caulk , or foam the sheathing to the studs. Infiltration is the greatest enemy of any insulation . That is one of the major reasons spray applied insulation works so well is it seals the air leaks off.
Use the 'Arkansas Framing " technique of notching the bottom of the stud so all the wires are at the bottom of the stud cavity and then are tucked carefully up the side of the stud to the boxes. This makes achieving a fully fill bay easier with the batts. Keep as much plumbing out of exterior walls as possible.
Make sure you foam every penetration into a stud cavity.
Acoustical caulk the studs before hanging drywall, this seals the inside surfaces against infiltration . Use plastic boxes made for this purposes around the electrical boxes to really get the best out of this. If not then use closed cell foam gaskets under the cover plates at electrical boxes.
I believe I read that also. Could have been on JLC website under building science. I thing it was a link. I will look it up later.
I found the start of my search on a foam installers website. They posted a link to the test that proved the convection loop in FG loose filled attic's and cherry picked a few sentences out of that test's summation and expanded them to include all FG in all situation. That cherry picked statement was then re qouted in to virtually every other insulation website that was done by other then FG. manufacturers.
I went round and round in circles trying to find the original source for the information and test. I posted it in a thread here at BT that riversong, piffin, myself and a bunch of others were discussing the worth of FG insulations . Couple of months ago at lost , no longer then that I don't think.
They can't get your Goat if you don't tell them where it is hidden.
Edited 5/5/2008 8:16 pm by dovetail97128