I live in the S.F. Bay Area…in a currently uninsulated Victorian house. The upstairs is currently gutted (new wires, plumbing etc.) and I have settled on using a sprayed in foam insulation (to completely seal the area, and help with moisture issues).
I know that there is a difference in R-values between icynene and poly (R. 3.6 vs R7), but I’m not sure that will matter that much given the fairly mild climate.
I got estimates for both and poly is about 2K higher (for a total area of about 1000 sf). The Icynene guy suggested that Icynene was better in my application because it is an old building that will shift and the icynene is more flexible and that will not pop off/crack like poly…Also, with the Icynene, the entire cavities will be filled (2X4 studs and 2X6 ceiling) whereas the poly would not completely fill the cavities (unless I really want to spend a LOT more money) because the R values are actually higher than the Icynene…
So…my questions:
What are the pros and cons to each?
What would you choose and why?
Replies
Icynene is one of several brands of open cell polyurethane foams. PUR foams are available in open cell and closed cell varieties which typically have R-values in the 3.5 to 4 per inch and 6 to 7 per inch respectively.
In your application I would go with an open cell foam. You have no need for a higher R-value than the 12 to 13 that Icynene or similar will give you in a 3.5" cavity. Remember that R-value only deals with heat loss through conduction and completely ignores loss from convection (air flow) and radiation. The energy efficiency of any foamed wall will be much higher than what you can achieve with traditional insulation as the foam deals with all the sources of heat loss. In an old structure, the gap sealing properties are especially important.
Also, your Icynene dealer is correct that the flexibility and breathability of the open cell structure will be an advantage in your climate. Chances are that the hard foam will break away from the frame in spots the first time you have a small quake. If the soft foam breaks away, you have much bigger problems than insulation!
Good luck
Can you see me smiling from here?
I was getting ready to respond that the PUR is better because it will add structrual rigidity to an older home. I can see the argument the icy guys make from their side too though.
Anyway - you also mention deciding on foam as a way to deal with moisture "issues"
If you have "issues" that could be a part of this decision and you might want to say what those "issues" are. I like the closed cell because it rejects water.
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Thanks guys for replying...good information.
Piff, I shouldn't have said "moisture issues." I like the idea of the foam providing a "vapor barrier" and that with the cavity completely filled there is (supposedly) less "mold issues" (at least that is my understanding).
That being said, it is an old house with redwood shiplap siding. As I have been restoring the outside, we have been taking care to seal up holes etc. but I don't think it will ever be as water tight as we'd like...
Is this one of thsoe old sidings where it was placed directly on studs and no underlying sheathing? If so, between that and the desire to eliminate potential condensation issues, i would undoubtable use the poly, though I confess to being suprised that it is that much more expensive. 'course I hear that CA is another world anyway
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There is "sheathing"--which is 1X6 redwood--the siding is on top of this.
The thing I liked about the Icynene is that bays will be completely filled...which by way of thinking (limited I know) would lead to less draft potential, less air for mold to form etc...
To be honest, when I called these two guys to get bids, I thought both were closed cell poly (one Corbond and one Demilac). I didn't realize the Demilac was an open cell product...
Any input?
The closed cell foam, in my opinion, is the best product. The icynene marketing angle that the bay is full means what? Full or 2" of gap (on the conditioned side) is the question. I would rather have a gap thank you. Reason being the fact that this is on the conditioned side so there is no extra moisture in the bay on the open space side. Additionally, that air temperature is virtually the same as room temp so there is no convective air circulation (looping) going on in that open space. The gap is very useful for extra wiring in the future.... electrical, phone, cable TV, phone, broadband, entertainment system, security system, next big thing, etc... Of course plumbing might also be required in the future.A set back for the SPF industry is the misunderstanding by a large part of the public that foam insulation completely fills the wall cavity. Many people DO NOT want that for many of the reasons I've mentioned above.BTW, the subject should probably read 1/2 lb vs. 2 lb foam. Here's a link on sprayfoam.com that discribes the differences: http://www.sprayfoam.com/index.php?module=ContentExpress&func=display&ceid=20&meid=&zone=40Icynene is by far the biggest player in the 1/2 lb foam market and does a very effective marketing campaign. Nothing bad to say about it, and at the same time feel that the 2lb is simply the next logical step higher quality. Stu
Thanks all for the input and information/links...still kinda conflicted though...Hmmm...
I, too, live in the San Francisco area, am renovating a Victorian house and am making the same decisions about Icynene versus closed cell poly and Biobased. I bet we are getting bids from the same installer on the Icynene (SDI, Inc?) and I just got the bio based soy product guy's contact information.I've had the same thinking process going on that you've had; pros and cons, etc etc. I guess I know this much:
1) Whatever I do, it will work better that fiberglass batts because of the reduced air infiltration
2) I hope nothing ever burns; apparently, all of these foams outgas cyanide when they burn!
3) But for passive, regular outgassing, Icynene is pretty benign; it has no effective outgassing going on 10-30 days after installation---and since it has the longest history as an open cell foam (about 15 years) and there's been no repeat of the disastrous formaldehyde disaster of the early closed cell foam installations, I'm hoping for a nice clean installation...gotta a young daughter and we're selecting everything that can outgas as green as we can; low VOC paints, formaldehyde free rock/MDF, etc, etc, etc...
4) With my attic ceiling and walls open, as well as the bedroom level ceilings and walls (putting in new electric and acoustical isolation), Icynene will be OK; but if you are renovating a Victorian, look out for any old knob and tube wiring that you are still using, because Icynene (so I've been told by inspectors and contractors) would cause a code violation; covering over the wiring causes heat build up---and that's dangerous I would guess the same thing applies to closed cell.
5) In a perfect world, maybe we'd do blown mineral wool (acoustic isolation and insulation) but I don't think I want to get into that.
6) The installer is not confident he can take care of outside walls where the plaster and lath is left installed unless he punches holes multiple holes in each 16" bay because foam won't make it into the areas that are protected by fire blocking....
7) as far as open space in the bays go: when they wire my house, spare conduit is being put in anyway; 5 or 10 yeas from now, I don't want to drilling and snaking things anyway. We're using a structured wire layout, so everything goes to a distribution closet on the 2nd floor anyway (computer server, central phone system, integrated AV system)...Anything else pop up on your radar screen? Finding people facing the same issues is exactly why this site is so valuable to me!NotaClue
Well, here is one more thing you may consider doing... install a sprinkler system.Before you burst out laughing, consider how low the installation costs are if the system is installed in a gutted home. While MA costs are pretty high (~$3/sq ft.), out west "new construction prices" are quoted as low as $1.5/sq ft. For this initial investment, you get a 10% discount on your HO insurance annually and peace of mind re: fires.Our home will have concealed head sprinklers that blend right into the ceilings. If the house cavities are open, I'd consider putting the stuff in and worrying less about how the Icycnene/Polyurethane will ignite, particularly if you're updating the electrical system at the same time.
House has a sprinkler system; it was once partitioned into four (4) units and code required it. So, we will upgrade it, and having it comforts my mind; after all, San Francisco burned to the ground once!
NotaClue
... if memory serves me correctly, SF burned down because of fires started by disrupted utilities, collapsing structures with fires within them, etc. While the modern-day Fire Departments may have far more tools in their arsenal than they used to, a sprinkler system inside your home won't protect you from external fires leaping onto your building. Your only hope there is to have fireproof siding, no exterior wood, etc.
You're right; however, remarkably, there are currently outside heads (the previous owner was an art collector too, and has two heads to soak down, I suppose, the side of the house which is closest the neighbors---we are a rarity in San Francisco, detached on all four sides....Glad to have the sprinklers on the inside in any case, given the cyanide gas which is created when the foams burn...and the hoped for delay or cessation of that event when the sprinklers go off....I have actually considered a foaming system for external protection (I know, this sounds psychotic); the house already has aqueous foam and pressurized water fire extinguishers I ordered and placed there before the construction began and will keep after it's done. Also, I ordered liquid fire retardant to place onto the wood surfaces where the plumbers will be torching and the hot membrane roof will be going down. When it was delivered, the contractor's foreman called me incredulously, laughed; then stopped laughing and starting telling me three different stories about houses that had taken fire damage from screwed up plumbing torch mistakes and hot membrane errors....then he asked where I had gotten it from and wanted the web address...In-laws house is at the edge of a National Forest in Oregon; they've almost lost it twice because of fires, we finally talked them into cutting everything back for a defensive zone and have considered the outside foaming system for them as well...
NotaClue
Edited 3/24/2005 1:04 am ET by NotaClue
Do you have a link to the outside foaming system?
This is the backpack/fire nozzle kit; note that this is one of the only two "gels" approved by the US Forest Service (and heck, they should know about protecting a house in the middle of a fire). The other gel works fine; only, it's only certified for delivery by a fire truck OR a helicopter dump bucket (eveyone has one of those sitting around, right?)We considered hard plumbing it for the inlaws, since a 74 year old isn't going to be wrestling a hose as a fire bears down on the house..
http://www.pmisolutions.net/thermogel/Enjoy!
NotaClueEdited 3/25/2005 2:16 am ET by NotaClue
Edited 3/25/2005 2:22 am ET by NotaClue
Question for you Stu, as I understand it, because the 2lb foam is "closed cell" there is still outgassing of HFC's etc. over a very very long period of time, where the 1/2 lb foam is open celled and outgassing is done in 1 or 2 days. I also understand that water is used in the open cell spray process whereas closed cell uses HFC's or other chemicals.
I also have some concerns with 2lb foam and settling, I have heard of cracking and shrinking of the closed cell foam due to the nature of wood which changes dimension as it dries.
I finally have a set of plans that you can give me a price on, contact me to arrange a meeting please
Thanks, Bigman
"as I understand it, because the 2lb foam is "closed cell" there is still outgassing of HFC's etc. over a very very long period of time, where the 1/2 lb foam is open celled and outgassing is done in 1 or 2 days. "The Cure time is 4 hours for my 2 lb foam. There could possibly be some gas given off after this but very very negligible amount. Your AC unit probably leaks more HFC’s then the foam does. The very old, now outlawed, urea formaldehyde foam is maybe where that information came from, not currently used SPF.
By the way, this has been used for 30 years successfully."I also understand that water is used in the open cell spray process whereas closed cell uses HFC's or other chemicals."Yes, the open cell foam uses water as an agent. The 2lb system uses HFC-245fa . This blowing agent has zero ozone depleting capability."I also have some concerns with 2lb foam and settling."The rigid closed cell foam does not 'settle'. That’s how you can spray it on a ceiling and it stays in place by itself. "I have heard of cracking and shrinking of the closed cell foam due to the nature of wood which changes dimension as it dries."I simply have not heard this one. The logic I would use to prove that false is this: roofing. The closed cell foam is used extensively in roofing applications. A coating is put over the top as UV and abrasion protection after. It is self flashing also. So you can spray right on the deck up against that brick wall. Now of course the coefficient of thermal expansion is way different between the brick and the deck and there is no problem there. Foam roofs rarely leak.Have you been talking to the Icynene salesman?Stu
Hi Stu,Thanks for some very interesting comments about 0.5 pound vs 2 pound foam. I am a new installer of BioBased foam in Cleveland, OH, and very eager to learn more about the pros and cons.BioBased, which offers both types, has been telling me about problems going from 141 to 245 as the propelling agent. They claim that 245 foam must be pressurized to be controllable. Are they blowing smoke? If not, how do you handle it in the field?How do you feel your two pounder stacks up in a bid situation? Can you compete on price with the half pound foam? Any tips, ideas, thoughts would be hugely appreciated!Thanks,
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Hi Stu,
I was wondering if installing a radiant barrier to the underside of the roof deck would be a worthwhile thing to do before foaming it with the closed cell poly foam.
I think the radiant barrier has to face an air space -- it doesn't work if you spray foam directly on the barrier.
Billy
Actually radiant barriers will work with foam on them providing they are Between the foam and the roof sheathing. Really only good for warm climates to reflect the suns heat back outside. In colder climates they are not going to reflect the houses manufactured heat back in.
So if I apply the radiant barrier to the underside of the roof decking thats visible from the attic it would help reflect the radiant heat back out. It gets pretty darn hot here in Oakland CA in the summer so I believe that something like this would be useful.
Daniel Neuman
Oakland CA
Crazy Home Owner
In a word, Yes. It will be more affective on the sides of the roof that get direct sunlight. There are all kinds of radiant barriers. Some are just a reflective coated mylar, others are a kind of silver coated buble wrap and there are even reflective ice & water shield type roof under layments. You could even get a two fer by using the rigid foam board that has a silver coating on it. Will be a little more work to install but it will give you some R value to further insulate the attic from the heat 'pushing' through the roofing.
Dan-
A call to a real scientist might be in order. Go to the web site of the foam material supplier and there is often a tech line to call. Often times you can ask for a product engineer or a test engineer and get a great detailed answer. Usually no one asks these guys anything near their area of expertise and are so thrilled someone is interested they will talk as long as you want. try corbond.com
or BASF.com/sprayStu
I agree with Billy. Radiant barrier means to me that it is a barrier against radiation tranmission of heat. That only takes place through space. So, I would have to deduce the usefulness would be nil.Stu
Any idea whether Icynene is prone to collect mold and mildew after installation? I saw a sample of icynene in an architect's office here once that had shriveled and turned blackish. My guess was that it had absorbed moisture from our very humid climate and grown some mold.I've never heard of this mold issue with Icynene before, but it kinda gives me the creeps.
I had icynene in our old home ,this home experienced extreme flooding. Lots of other surfaces developed mold growth, the foam insulation showed no signs of mold growth or any degradation of the material. Our new house has polyurethane foam in four years there are no indications of foam shrinkage at the studs. The polyurethane foam sticks everything together and stiffens wall assemblies.
Thanks!
Your comments about mold (and lack thereof) are reassuring.
NotaClue
Just a side note: I assume the exterior siding is wood.. .if so make sure that you prime the inside of the siding.. .it will help the exterior finish from peeling.
Here are some random thoughts from someone who has both materials in a similar house. We gutted out Victorian to update the insulation, piping, electrical, etc. We settled on closed-cell foam in the old part of the house and Icynene in the new part. The 4" stud cavities in the old part are filled to about 3.5" out of 4" with the closed-cell foam, the 5.5" cavities in the addition are filled 100% with Icynene.
So, in theory, both kinds of walls will have about the same R-value. The built-in vapor barrier of closed-cell polyurethane makes sealed attics/cathedral ceilings simple (though you usually have ot cover it with a fire-resistant sheathing on the inside). Due to the polyurethane, we may be able to reduce the capacity of the cooling system by another ton...
As for the Icynene vs. closed cell Polyurethane stickyness/fill, etc., I think that depends largely on the installer. In our case, the insulation contractor pushed hard for the usage of Icynene, presumably because it is easier to work with after it has been applied (much more friable). He also mentioned its greater flexibility/fill characteristics as an advantage. However, my personal experience does not match the promises of Icyenene.
Don't get me wrong, I am happy with the stuff and 99% of the work. However, there were several areas in the house where the Icynene did not fill the cavities 100%. Also, several areas featured "slugs" in the cavities had not bonded to the studs because a non-sticky skin formed before the expanding slug hit the sides of the studs. Not a big deal, we simply came in with our handi-foam cans to fill in the holes after the fact.
Meanwhile, in the areas where closed-cell foam was used, there were no such issues. I could hear the closed-cell foam keep expanding for hours after its initial application, so the studs were sealed tight. The closed-cell foam is also much stiffer, so it's harder to shave down. Given that we rebuilt the basement from the ground up, I hope we won't have settlement issues to deal with...
Using both PUF and ICY?
We're doing a barn-to-house conversion in Michigan. Post-beam, balloon construction. Cathedral ceilings will be filled (2X6 rafter bays) with polyurethane up against the sheathing; then covered on the inside with 1" extruded polystyrene ("pink") sheet as a thermal break/vapor barrier, taped, drywalled.
QUESTION 1: I'm not sure the resulting R value will be enough in the roof. (PUF outgassed R7/inch X 5= 35 + XPS R4 = 39Rs total). Should we fur down and go for more? We're going to be heating 3,500 sq ft, radiant hydronic infloor and panels with an oil condensing boiler.
The insulation contractor suggested that we spray 2-3" of polyurethane into the 2X6 wall cavities against the exterior wall sheathing and leave the remainder empty (R 14-21 total).
I was going to either leave the remainder of the bay empty as the contractor suggested or fill with cellulose for more Rs; install "pink" foam sheet on inside, tape, and drywall. If sealed pink foam is also a vapor barrier, I've got it on the inside of the wall, which should be correct.
QUESTION 2: If PUF is a vapor barrier, isn't it on the wrong side of the wall? Besides that, wouldn't I end up with double vapor barriers? "double" ain't good here. Shouldn't this foam be open cell Icynene rather than PUF? That way any moisture getting into the wall should migrate to the outside (OSB/plank sheathing, felt, board/batten cedar).
Hubby says I'm thinkin too hard.
This message is very timely as I also have a Victorian in the SF bay area region (Oakland CA) and I am looking to do the closed-cell-foam-on-the underside-of-the-roof-deck-with-no-ventalation-thing. I have searched the archives and boy is this a hotly debated subject. For me the fact that I do not have to retrofit soffit and ridge vents is a big plus and there is no way Oakand CA gets as hot as Las Vegas where they did the testing. Since we are local I would be interested in hearing your experiences with this particular system and with the contractor.
Thanks,
Daniel Neuman
Oakland CA