Polyurethane SIPs and delamination - a myth?
Last Post 21 Sep 2009 11:19 AM by azbuilder. 49 Replies.
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RasThavasUser is Offline
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10 Jan 2009 08:02 PM
I recently talked to a builder who uses EPS SIPs but won't use PU SIPs. The reason, they say, is that PU SIPs offgas, which results in shrinkage of the foam which leads to delamination. I don't recall hearing this before. Can anyone shed some light on whether this is true, partially true, used to be true or is simply wrong?


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10 Jan 2009 08:20 PM
Posted By RasThavas on 01/10/2009 8:02 PM
I recently talked to a builder who uses EPS SIPs but won't use PU SIPs. The reason, they say, is that PU SIPs offgas, which results in shrinkage of the foam which leads to delamination. I don't recall hearing this before. Can anyone shed some light on whether this is true, partially true, used to be true or is simply wrong?
It is true that PU will shrink with age, wether that is the reason they delam I do not know, they also loose R-value with age.
I can tell you from experience in cutting them , the dust is itchy to the skin . 
PU will offgas,  some mfg. claim to have over come that problem, but I am not sure if they all have.



Chris Kavala<br>[email protected]<br>1-877-321-SIPS<br />
CHLUser is Offline
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12 Jan 2009 07:43 AM
Some people who use EPS sips never seem to miss a chance to knock PUR panels - and most of the "knocking" is unfounded or downright lies. Let me explain. First, there are very few polyurethane panel companies in the US but those that do make the product are very professional and can educate you about the product. Polyurethane is a widely used foam throughout the world, from car seats to Icynene spray foam (both open cell) to PUR panels or bowling balls (both closed cell) polyurethane manufacturing is a chemistry that is well known and stable. Some of the best known glues in the world, like "Gorilla Glue" are polyurethane based. This is a HUGE difference between PUR panels and EPS panels. PUR foam is its own glue - where EPS panels require a different material and manufacturing process. When you add components or processes you introduce opportunities for error. Search the web - you'll find many instances and discussions of delamination on EPS panels yet very few for PUR panels. The only way PUR is going to delaminate is if the foam is not mixed correctly and this is a manufacturer issue, not a product issue. In fact some PUR panel companies offer either very long or lifetime warranties against delamination because that is one of the more reliable parts of their product - they just don't worry about it.

Phenolic foams will shrink but this is not polyurethane - again, properly mixed polyurethane foam does not shrink regardless of what some EPS guys say.

Cured polyurethane foam DOES NOT OFFGAS. Again this shows some ignorance but perhaps understood. Polyurethane is a plastic and it will cure usually completely in about 24 hours. PUR foam DOES "LOSE" R-VALUE, but usually in the range of 7-8% from initial blown but that entirely depends on the siding material used and it's permeability. When your initial blown R-value is typically between 7.5 and 7.0 - and you lose 7-8%, you are still almost twice as energy efficient of standard 1lb EPS (typical densities used by EPS panel manufacturers). Look up LTTP - this stands for Long Term Thermal Profile. Listen, your refrigerator is probably insulated by PUR foam, NOT EPS. Think Igloo cooler or the cheap white styrofoam you buy at the gas station when you are taking your kids fishing. Yeah, it's like that.

When PUR foam "loses" R-Value, it is essentially "in-gassing", not off-gassing. Again, let me explain. The foam is shot into a panel in an EXOTHERMIC reaction. This reaction creates billions of tiny bubbles of (hopefully) close to uniform size and density. But when these bubbles cool off the volume of the bubble remains "large" (it should still be very small) but just as lower pressure shrinks gasses the pressure inside of the bubbles decreases relative to the ambient air pressure outside of the panel (see Charles's Law or Boyle's Law for the relation between temperature and volume and pressure for gases). Now the blowing agents typically used inside of the panel have non-polarized molecules that do not promote molecular cross linking (and therefore thermal conductance) - that's why they are preferred. But a small "vacuum" inside of these bubbles over time (again, depending upon the siding used) will draw in ambient air - air that may contain small amounts of moisture. That moisture has polarized molecules that will dutifully line up and conduct thermal energy but again, in incredibly small amounts. Panels cured in dry environments will have different LTTP profiles as opposed to those that occur in moist ones - but again, it's miniscule. This is like a gnat's ass when compared to the in-foam voids and moisture present in EPS foam - get a microscope and look at it and the air is free to move in just about any direction - that's why it has approximately half the R value.

Regarding "itchy" foam (?), what the heck is someone doing cutting panels on a job site? That creates many opportunities for error - voids, delamination (of EPS), moisture ingress, unskilled labor cutting panels wrong, etc. PUR panel systems are "engineered to fit" and different systems have ways to accomodate for foundations or frames that are off.  Again, speak to the manufacturers for the straigth scoop and evaluate on your own.

Your builder friend just probably doesn't want to pay more. PUR companies can not always command the premium that their product offers and EPS is CHEAP in comparison. Again, there's a reason that the vast majority of panel companies in the US are EPS and not PUR, but there's also a reason why the vast majority of construction panels sold in Europe are PUR - they don't have the huge chemical industry lobbies that the US does and safety and insurance regulations discourage structural EPS panels. Please do not hesitate to ask more questions if you have them. You're doing what you should be doing - asking for input and researching your questions.  Through indpendent research you should be able to weed through the chaffe and get to the kernals - the "meat" of truth that you're looking for.


chuck07User is Offline
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12 Jan 2009 08:26 AM

I'm confused.  It sounds like in paragraph 4 your explaining how PUR panels shrink.  How does that support your premise that they don't shrink?  I don't think there is any question that PUR is a good glue.



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12 Jan 2009 08:30 AM
In physical size there is no shrinking.  The polyurethane plastic - after about 24 hours - is inert - simply a solid plastic.  The pressure inside of the bubbles inside of the plastic may change, however (again, we're talking at the molecular level).  The bubbles are formed in heat and dry while still warm but over time the gases inside of them cool and the molecules "close in", creating the negative pressure inside of the larger bubble.  Let me know if that's still not clear and I'll try to explain another way.  Getting ready to board a plane so my apologies if my reply comes later.


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12 Jan 2009 08:38 AM
CHL:

Fords or Chevys, depending on what you sell, is what you will push.
All of the statements in my previous post were facts.

Your tap-dance was amusing and as other proponents of PU they are always on the defense.

below are links to OSHA and other agencies expressing the dangers of PU, you will be hard pressed to find any dirt on EPS

http://www.osha.gov/SLTC/isocyanates/index.html

http://www.cwa-union.org/issues/osh/articles/page.jsp?itemID=27338964

http://www.cdc.gov/mmwr/preview/mmwrhtml/00053340.htm

http://healthychild.org/resources/chemical-pop/polybrominated_diphenyl_ethers/

http://www.freshpatents.com/Process-for-the-production-of-polyurethane-products-dt20070517ptan20070110877.php?type=description

http://www.arap.org/adlittle/4.html


Chris Kavala<br>[email protected]<br>1-877-321-SIPS<br />
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13 Jan 2009 07:05 AM
Mr. Kavala, I've taken a look at some of your other postings and now understand a little more about you. You are a salesman and you shamelessly promote your product - very often in entirely unrelated questions - at the expense of truth and science. What you call "dancing" we in the reality based community refer to as science. And perhaps not surprising you did not disagree with anything I said with any substantive information.

You presented many links listing the dangers of the COMPONENTS of polyurethane. Yes, you got me, some of the components of your refrigerator's insulation or your car seats or foam panels (yes, EPS and Polyurethane) can harm you but because in fact the components of the chemical reactions actually CHANGE THE CHEMICAL STRUCTURE of the compounds THEY ARE NO LONGER THE COMPONENTS. OSHA has a health warning against styrenes used in EPS - http://www.osha.gov/SLTC/styrene/index.html - including effects of the central nervous system, etc., yet we know that chemical reactions make EPS inert, just like PUR. Cast not the first stone, Mr. Kavala. You have presented no convincing or supported evidence of your implied comments that PUR foam kills people. And I noticed from the time stamp how quick you were to produce that list so I'm sure with only a little research I would see you've done it before.

I'm reminded of the Wisconsin governor who, when confronted with our government's "concerns" that medications dispensed in Canada were unsafe and therefore Americans should not cross the boarder into Canada to get the medicine they so dearly needed but could not afford here, said "Show me the dead Canadians". Simply tossing out a bunch of links to produce the appearance of proving your point - when in fact it doesn't - (think "Show me the dead refrigerator owners") - does not do this message board or the viewing public any service. And by the way, no US manufacturers of PUR panels use TDI mixes - that wouldn't make sense in the first place - and you may want to do a little research on the flame retardants (so now it doesn't burn, it just vaporizes) used in EPS - not pleasant stuff, and sometimes the same ones used in PUR.


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13 Jan 2009 07:25 AM
CHL;

if you went thru all 866 post then you know I offer much more to the forum than promoting steel SIP construction.

If you knew what you were talking about you would know that the EPS flame redardants off gas in 24 hours or less, long before they get to the jobsite.
Unfortuately all the carcengenic chemicals in PU continue to off gas for years while its in your home, ain't nothin green about that!
While some PU mfg. have made the effort to clean up their industry, all have not.
I don't live in a refrigerator, so a small anount of PU in the home is acceptable.
If you looking for dead Canadiens go to the cemetary


Chris Kavala<br>[email protected]<br>1-877-321-SIPS<br />
SimonDUser is Offline
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13 Jan 2009 07:39 PM
Hi, I'm a SIPS Designer down here in Florida. I've been in the biz of SIPS for about 12 years. Worked in an EPS SIPS manuf. plant early in my career and now I'm an independent designer who has designed many buildings with both kinds of panels. My opinion is that both types of panel can experience this problem if not manufactured properly. But all things being equal, I think an EPS panel would be more likely to delaminate than a PU panel, because EPS panels require a third component (the glue) between skin and foam core and with a PU panel the foam core is the glue, having one less component that could fail. However, this one issue is not grounds to dismiss the other kind of panel as inferior. The best panel is the one most readily available in your area with the company having some kind of track record for satisfying its customers. (Hey Chris! Know who this is?:-)


Building Designer<br>PANELfusion, LLC, Tampa, FL<br>simon@panelfusion(dot com)<br>"Metal SIP Advocate"
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13 Jan 2009 07:42 PM
SimonD;

yes your the guy that I shared an office with


Chris Kavala<br>[email protected]<br>1-877-321-SIPS<br />
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14 Jan 2009 10:22 AM
I have to say I'm never surprised that the EPS guys say one thing and the PU guys another, but I use either one and after eleven years, I recommend only PU to our clients. I've worked with three different PU manufacturers and have had no problems with the product (I don't count a few onsite adjustments as problems...just construction). I know that many people use EPS and they've been satisfied, but I'm more comfortable with the PU system. I like the more dense foam (thinner panels). I like the fact that my panels are always exactly the right thickness. I like the fact that PU doesn't burn and does only degrade at a much higher temperature than EPS. I'm not a manufacturer and can pick my supplier, so I'm not selling, just commenting.

The myths and quasi-facts that abound about each are, for the most part, just taken out of context and twisted. I've seen that on both sides. We looked at what we want the panel to do and at our experience with both and chose to use PU.

Dollar for dollar, PU is the better bargain. Just my two cents worth.


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15 Jan 2009 09:25 PM

Whoa there everyone! I won't enter the debate on PU vs. EPS but I will say this: We should all recognize that no matter what the foam, SIPs are what we are all promoting to sell and build with. It's like one posting said: Ford or Chevrolet. Address the specifics with the panel manufacturer. Since there may be challenging agendas here, lets work together to promote SIPs overall.

We offer a 50 year guarantee against delamination and rot for our in ground foundation and frost wall panels, and they're EPS. So we've clearly addressed the 'glue' issue. If Boeing can build a plane and many of the parts are glued together, I am sure the glue in a SIP panel can be sufficient and adequate to do its intended job and besides it's probably a PU based glue, how ironic is that?

Build with a quality SIP and if EPS or PU, you will have a MUCH better house in many ways.



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15 Jan 2009 09:45 PM
In Canada the Gov. is planning tax breaks for home renovations but nowhere is there are mention of Energy Efficient Construction in the reno's.
Forget SIPs, ICFs lets Promote Energy Efficient Building.

PS EPS is better because for dollar it lasts longer.


Build Smarter with Structural Insulated Air<br>http://StyroHomeNews.blogspot.com
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16 Jan 2009 09:50 AM
OK, you've got me curious on this one.  I'd like to hear your reasoning behind "EPS is better because for dollar it lasts longer."  I think this is one more misleading claim for EPS but I hope I'm wrong.  Foam industry sales persons will tell you that both EPS and PUR will last indefinitely.


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16 Jan 2009 05:05 PM
The reason many want to ban EPS, is that it will not break down in time. On the other hand put Polyurethane in the sun and many types will turn to dust in 10 years. Don't always believe a sales person I say.


Build Smarter with Structural Insulated Air<br>http://StyroHomeNews.blogspot.com
Louie FischerSIPs User is Offline
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16 Jan 2009 05:11 PM
How far can typical PU SIPs span between support members for roof panels. Most PU companies only sell 4-6" panels. Also, how often do anyone's panels delaminate. We warranty our panels for a lifetime. To all potential SIP builders and homebuyers: Most all companies not making SIP's in their garage will offer the same warranty against delamination. These scare tactics are silly and rarely happen. In the three years I have been selling SIPs our company has not had a case of delamination. Also, I have not heard of any other reputable SIP company selling "structural", panels that have delaminated. All panels leaving our plant undergo quality control measures and our production process is third party tested every 4 weeks. Would all these companies still be in business if panels delaminated. I'm sure there is a horror story out there, but I would be willing to bet out of the millions of square feet of SIP panel sold each year, a small fraction of 1% have a delaminatin issue. Of that percentage I'd bet they are caught upon installation and replaced free of charge by any company


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16 Jan 2009 07:42 PM

You are correct.  Polyurethane foam, when exposed to UV light, will break down through a process known as UV degredation (many polymers do this).  This does not affect PUR sip panels however since the foam is not exposed to UV light when a structure is erected.

EPS's huge opportunity is to develope cost effective recycling centers because it will last for friggin' forever under just about all natural conditions.  It certainly is possible to recycle EPS, but as yet is not practical on a widespread basis due to the lack of recycling centers.  The term "recyclable" is used often but to little practicle purpose.

We would like to think that all SIP panels, regardless of foam core, would last for several lifetimes, yet this will depend most of all on the quality of construction of the building itself and the integrity of the moisture envelope to prevent a break down of the siding material or degredation of the EPS bead bond.  And yes, steel sips or fiber cement sips help to reduce opportunities for this to occur.



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16 Jan 2009 07:53 PM

Structural span is directly related to the thickness of the I-beam as determined by the web.  This equates to the width of the foam core.  Because of the density of PUR foam and its insulating properties PUR panels do not need great thickness to produce large R values.  For an R40 or R42 roof panel a PUR panel manufacturer only needs to make a 6.5" panel.  Depending upon EPS density the EPS panel supplier will need a 10" or 12" panel to achieve the same R value.  But what that buys the EPS panel supplier is greater span and that information should be available on their ICC-ES test data if not on their website.  Typically 6.5" PUR panels will not span greater than 8ft laterally unless reinforced internally.  Spans are generally cited in the horizontal plane and can be often greater in panel length if the panel is running the pitch of the roof (ridge to eave).



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17 Jan 2009 07:59 AM
an 8 foot span is pitiful!  most EPS core steel skin panels will span twice that


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17 Jan 2009 01:58 PM
Our 6" steel panels will span 19ft.


Chris Kavala<br>[email protected]<br>1-877-321-SIPS<br />
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