Closed vs open cell spray insul in unven
I keep reading and hearing how closed cell insulation is the way to go for unvented rafter/roof applications but my insul contractor, who handles and bids both keeps pushing the open cell
(icynene). They debunk the claim that CC is better as a vapor barrier saying 90% of perm is air carried and debunk CC’s rigidity advantage saying the CC shrinks away during shrinkage caused by gassing caused shrinkage. What gives? Are the articles in FHB and JLC wrong or are the profit margins for Icyene so much better. Both products are good I’m sure but at this point I just want to understand this. Confused in Cincinnati.
Thanks every one and thanks FHB, its great to have the conversation!
Edited 11/21/2008 12:50 pm ET by luke in cincinnati
Replies
He's got open cell equipment and inventory, so it's better.
http://www.quittintime.com/ View Image
so ya think closed is better, nice web site
Thanks. Kudos go to FatRoman. He designed it.
See the post above.
http://www.quittintime.com/ View Image
Edited 11/19/2008 7:52 am ET by seeyou
closed is definitely better.I have never used open.I keep hearing these stories here of how moisture collected in the open celled, like a sponge. obviously other factors contribute to something like that, but it cannot happen with closed cell foam. Wet foam not only causes other problems, but it fails to insulate.One of the things that bothers me with the whole open cell side of the industry segment is their advertising. I keep seeing them make the same claims that have been proven for years by the closed cell insulators (like Corbond who has led the whole industry in testing and white papers and consumer education) but the open cell guys are projecting that information from closed onto theior open and I never see them back up the claims with any studies and proof. I think they read the Corbond book, "Walls that work" and say to themselves, "Yeah, that sounds good" so they incorporate that info in their own sales pitch on the "assumption' that it is also true for open celled.Some is and some ain't
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Dumb question here. How do you know if you are getting closed cell vs. open cell. Does it say so on the raw material drums? Are there trade names or material names. How do the cured products compare; color, texture, shape of the cells...?Are there photos of the cured open cell and closed cell available?
They should all be honest enough to say, tho I have heard here of one installer claiming falsely that his was closed cell.The icynene is softer and flexible and usually white. it is open celled.The polyurethene foams are the closed cell. They are firm after curing a few minutes. Naturally light tan/brown, but Corbond adds a pink dye as well as insect and fire retardants. It wqill repell water.There are also soy based foams for the green conscious crowd. I am unfamiliar with them.But ANY seller or installer should be able to provide you specs. If you have the trade name, you can look up the pdf version of the MSDS sheet online.
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CC is stiff,OC spongy
If he is getting too much shrinkage cracking in the closed cells installations, it is because he is not installing it right. It has to be metered/mixed right, at the proper temperatures, and sprayed on correctly.
The wrong mix, or spraying in too cold of a temp, or trying to spray too much in one pass, will all result in cracks and separations.
So for him to blame the material and speak against IT when his skill set is what is lacking, puts his ability to speak on the matter into question.
My guess is that he makes a higher profit for less work with the open celled, thus his prejudice.
I don't suppose that in his analysis, he admitted that closed gives you nearly twice the R-value per inch?
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Are there long term shrinkage issues? We've all seen great stuff that has shrunk over the years - in an unvented roof gaps could be a good path for moist air. I just wonder what will happen 50 years down the line. I had an icynene insulated roof that had a leak - soaked up water like a 1000 sq ft sponge but it did dry out eventually. it did stay stuck to the framing.
Great stuff and spray foam are different critters. Great stuff starts curing when it hits air. Spray foam starts curing when it's mixed at the nozzle. The different foams have different properties.Rebuilding my home in Cypress, CAAlso a CRX fanatic!
Tu stultus es
if it doesn't split or shrink in the first day ( usually the first couple minutes) it isn't going to shrink and crack.If sprayed too thick though, you may not notice the shrinkage immediately. It can crack inside a thick pillow, without showing at the surface. It should be sprayed in lofts of about 1-1/2" to 2" in a pass. The guys I see working do one stud bat@", then go to the next one 2", then back to the first.
Ye3s, it kicks that quick. So when a newbie poorly trained or not motivated to do it right tries to fill an entire stud bay at one time, you get cracks. It has to do with the way it cures, and the fact that it is exothermic.For instance, Fypon railings make their product from the same foam, tho slightly denser. The thicker pieces such as a 6" railing or a 10" newel post, have a 2-6" PVC pipe centered in the form. There are other reasons for this, but one major reason is to allow even cooling as it cures.
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Thanks. I was wondering about the very long term. on another note the icynene guys stress the gasses that polyurethane gives off in a fire. Of course that may be the least of your problems as your house burns...
They all do, and I'll have to pull a video off my camera for you. I took a torch to a piece of closed cell foam that I cut out when I installed my suntubes. When torching the foam, it smokes. As soon as you pull the torch off of it, it stops immediately. It does not burn (or at least not the product from Resintech that I had install), nor support a flame, it didn't even have any cinders. Try taking a torch to your mattress/couch/draperies, etc. and see how quickly you have an inferno. If you're really worried about the gasses it gives off in a fire, it's a moot point, because your house will probably be fully engulfed by that time.Z
"the gasses that polyurethane gives off in a fire"I have yet to see any icy guys demo how safe their product is by breathing the vapours off of it.Once covered in sheetrock, the insulation - either kind - will be less danger, later on in a fire than the carpet, sheet flooring, and a hundred other items used in the house. Even the soles of your shoes will be off-gassing as you hotfoot it out of there
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That would be quite a demo :-)
Closed cell is a vapor barrier. No doubts.
Look up the perm rating of open cell. It's no where even close to being a vapor barrier.
Both prevent air infiltration, but open cell is in no way, shape or form a vapor barrier.
Mongo
right, Open Cell is not a VB but the Icyenen guys say a very high % of moisture is air borne & therefore the OC air barrier achieves the nec protection of wood from due point moisture. lets remember the OC is about !/2 the cost of the CC for the same R-V. My original question was whether there is any validity to this in my climate, CincinnatiI'd love to spend the extra $3K on finishBy the way, I poured some water into a sample of icynene, none came out, it didnt perk through, it just sat in there for days. (?)
Don't let him try to pawn off the idea that just because moisture vapor is airborne, and that open cell is an air barrier, that therefore air borne moisture will not permeate into a thickness of open cell foam. Open cell can certainly work, the big difference between the two is R-value per inch, and that open cell may require a vapor barrier in some applications due to its perm rating, where closed cell will not.As far as the dew point claim, sure, with sufficient thickness either foam will cause the dew point to fall within the thickness of the foam. Open cell has no advantage over closed cell in that regard. As a matter of fact, I'd say that closed cell has the advantage due to its higher R-value. A lesser thickness of foam is required to get the dew point to fall within the foam. Both foams work. I just wouldn't advise using open cell below grade or in a closed roof assembly.The best part about foams is the air infiltration. In my opinion R-20 of foam will outperform R-50 of fiberglass batt insulation.
Thanks Mongo, I guess the 3 grand is worth the piece of mind. I'm sure going to be looking for a great installation job.
"lets remember the OC is about !/2 the cost of the CC for the same R-V. "That must be a regional anomaly
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2 CC bids- $6,550 & $6,800
2 OC bids-$3,700 & $2,900 (icynene)
I also got a celluose bid (because I thought they did foam too) $$2,500Thanks to every one and to FHB for supporting the conversation. over and out.
Is that for the same thickness of each, or the same R value?
John
the quotes are all slightly diff.
OC is full fill-4"walls, 6" rafters, its an old house
CC is 3" walls, 4" raftersso about the same R-value.
No, that is not even close to the same R-value!closed poly is about R7
open icy is about R3.5so 3.5" ( not the 4" you state unless you are using some rough cut studs) of OC icy gives you a total R value of 12.25 in the walls. full 4" gives you R14Compare that to CC poly of 3" which gives you R21 walls. a minimum of 50% more insulation The on to the rafter space.
6" CC is R21. That is minimally acceptable for overhead, especially where you can get condensation issues in a catherdral ceiling.
Withthe CC poly at R7/inch you can have a vapour barrier instead of a sponge, and R42!Yes, it is more expensive, but there is the insurance against moisture problems, and over time, the added insulation will pay for the increased cost many times over.If you elect to still go with the open celled for the cost savings, the only way I would want to do that is to add an inch or inch anda half of Thermax across the rafter faces and tape it, for a VB, and to prevent thermal bridg, and the necessary minimal R-value total. This is rated about R7 also.
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Thanks for the reply, Isn't "R-7" optimistic for CC, the ads say 6 to 6-1/2, but the articles seem to say aged is closer to 5.5, I'm going with the CC because of the VB and yes its an old house with full 4" & 6" members, some are more.
Got a building inspector involved? Mine wouldn't accept partially-filled stud or rafter bays, because the code-required vapor barrier needed to be in continuous contact with the insulation. Given my rafter depth, OC foam was the only way to fly.
Would he have accepted CC foam as both insulation and VB? Don't know for sure. Do know that he would not accept a "hot roof"- he insisted on ventilation under the sheathing regardless what insulation was used.
As others have said, both OC and CC foam contain moieties that will release hydrogen cyanide and carbon monoxide when burned, but so does the foam in your furniture- and the furniture will be engulfed long before your drywall burns through.
thanks, I have spoken to a friend at the building desk, they dont have a "rule". He suggested I bring industry info in to prove the VB claim of CC. I'm bringing this up with my contractor to see what he's willing to do. Seems like the CC industry'd be working hard on this.
all I have used is rated 6.8 to 7http://www.corbond.com/rvalue2.htm
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I'll see your link, and raise you one:http://apps1.eere.energy.gov/consumer/your_home/insulation_airsealing/index.cfm/mytopic=11600I'm an open cell guy. Mainly cost. I put in what people want, and the CC vs OC cost difference has so far dictated that they want OC. OC does have a couple of other advantages. The pemeabilty property will let you know if you have a leak in either the roof, or a roof/sidewall situation. Fishin a wire seems easier with OC in a 2x4 wall. OC expands in the path of least resistance, so, it doesn't nudge things apart. Other than the leaks, not huge advantages, but...CC does add much more rigidity.As far as the r value, my thinking is that stopping air infiltration is the key to effective insulation, and both do that extremely well. So, with the air stopped, I'm not convinced there's not a point of diminshing return on the r-value there?... plus, I love playing with open celled scraps.Question though, how do closed cell sprayers fill the gap between the top plate and the roof deck?
edited to add: If were the OP, I do think I would consider using CC in the roof because of his rafter size. Now you see this one-eyed midget
Shouting the word "NOW"
And you say, "For what reason?"
And he says, "How?"
And you say, "What does this mean?"
And he screams back, "You're a cow
Give me some milk
Or else go home"
Edited 11/24/2008 6:58 pm ET by Snort
I agree on all that, and I did state that CC is more expensive. I was simply pointing out that it is not AS more expenive RE OC as the OP had thought, given his incorrect assumptions on R-vluegap at roof deck???quite a few of our homes up here are that silly style with no roof overhang so that eliminates, but for others, some carboard or rosin paper can be stapled up there, or 1/2" foam cut an friction fit in place before spraying. All they need is something to begin building up on.
???Would open celled be any different in that regard?
Do you use a VB over your OC? Especially in cathedral ceilings?
since yopu are not in an extreme climate, I would not expect the condensations problems to exhibit as much for you as someone in CO, Montana, Canada....
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No vapor barrier on cathedrals. When it's really hot and humid the ac's on, which keeps things pretty dry.The gap I was talking about would be the rafter bays. With the oc, they spray a little on the underside side of the roof deck above the top plate, wait a few seconds for some expansion, snag the end of that oc patch with the tip of the wand, and flip part of it downward, where it sticks to the top plate. Makes a little oc bulkhead that stops the stuff from getting into the soffit. Kind of like a neat little dance the guys do, so, add entertainment to the oc! Now you see this one-eyed midget
Shouting the word "NOW"
And you say, "For what reason?"
And he says, "How?"
And you say, "What does this mean?"
And he screams back, "You're a cow
Give me some milk
Or else go home"
CC kicks up hard too fast for something like that, IMO
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thanks for the link, no dealers in Cinci though,
see Snort's link from the DOE also.
I have really never heard of CC being as low as five, making me wonder what kind it is you have available that only advertises R5
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it was 5.5 and no its always advertised as 6.5+ but after off gassing (aged) it goes down.I dont see the DOE link you mentioned.
Thanks again Luke.
http://apps1.eere.energy.gov/consumer/your_home/insulation_airsealing/index.cfm/mytopic=11600it does drop some over a couple years with aging, but not over fifteen percent like that.
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That is about what I expect for same thickness, but not for same R-value.
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