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creeky
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# Posted: 25 Jan 2014 11:28
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recently there's been a bit of talk about insulation. don't know why. what with this mild winter we're not having.
so I looked up my two favorite insulations for safety:
Roxul: concern: offgassing: source: company
"Although a formaldehyde-based organic binder is used during manufacturing, a high-temperature curing phase virtually eliminates volatile compounds. The result is no measurable free-form formaldehyde in the final product and no volatile organic compounds that can off-gas. "
this material is completely safe. and to all intents and purposes. fireproof. it is commonly used as filler/insulation around wood stove pipes.
Polyisocyanurate insulation: concern: offgassing and flammability
Flamability:
Polyiso is stable over a wide temperature range (-100°F to +250°F) (greenbuildingadvisor dot com)
Polyiso has a melting point of over 392° Fahrenheit (200° Celsius) and is made up of minute closed cells that contain hydrochlorofluorocarbon (HCFC) gas, which is non-flammable, inert, and an excellent insulator. (wisegeek)
Offgassing:
Polyiso uses pentane, a hydrocarbon, as a blowing agent. It escapes extremely slowly, over many decades. If you own a car and visit a gas station, you probably breathe in more hydrocarbon fumes every time you fill your gas tank than you'll get from the polyiso insulation in your walls over many decades. (green building)
Conclusion:
Safe to use.
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MtnDon
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# Posted: 25 Jan 2014 11:56 - Edited by: MtnDon
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Polyiso is usually used on the exterior, at least that is the method the manufacturers have in mind. Installed on the exterior there is virtually zero concern about breathing any off gassing anyhow.
It's hard to beat the R 6.5 per inch of polyiso. It will melt and it will burn though so must be covered in 1/2" gyproc or equivalent to give occupants a fair chance at escape in case of a fire.
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bldginsp
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# Posted: 25 Jan 2014 15:41
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I don't know, but I imagine (or hope) that if an offgas producing insulation has a means of venting off the gasses in the assembly in which it resides, that the gasses will vent out and away from the air you breathe. So, in a framed underfloor situation with crawl space and venting, far less of the gasses will work their way up through the cracks in the floor plywood, than would enter the air space underneath and vent off. Same with any ceiling assembly that has venting above the insulation, which all should.
But in the walls there is no venting, so the gasses, I suppose, would be more likely to end up in your air, or at least some of it.
I bought a bunch of R30 insulation off Craigslist which I'm sure is the old stuff and will offgas formaldehyde. It's going in the subfloor above a well vented space, and the plywood subfloor will be glued down with Liquid Nails, hopefully sealing to an extent.
In my vaulted ceiling I'm using polyiso, and will place a 10 mil moisture barrier beneath it which, I hope, will limit passage of gas downward as well as moisture upward. As well, there will be cross-ventilated air space above.
But for the walls I plan to use Roxul for the reasons you quoted. It should be said, though, that manufacturers of fiberglass have reduced formaldehyde use in the glass. However, I don't know how much or how to gauge whether what they have done will reduce exposure to 'acceptable' levels. What is an 'acceptable' level for a carcinogen, anyway? If it's there, it's increasing your chances of getting the disease.
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bldginsp
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# Posted: 25 Jan 2014 15:47 - Edited by: bldginsp
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MtDon- I am unaware of any requirement to cover polyiso with gyp board as a fire protection measure. Is that code, or a manufacturer's listing requirement? Or what?
Edit- on doing a little googling, I found that the older polyurethane insulations were very flammable, but the polyiso types are less so, and meet code fire resistive ratings without addition of retardants. But, thus far, I haven't found anything clarifying when/where gyp must be used between insulation board and living space.
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MtnDon
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# Posted: 25 Jan 2014 16:09 - Edited by: MtnDon
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Good question bldginsp, Printed right on each sheet of Johns Manville polyiso the a statement that states the material must be covered on the inside by 1/2 gyproc or equivalent 15 minute fire barrier, becauseof its flammability. If this is actually listed in the code, I don't know exactly where. I have seen the vigor that any of the foams do burn with.
One problem is finding the minute rating of other materials. I believe T&G 1x wood siding will have no problem beating the 15 minute barrier. I just can't point to a paper.
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bldginsp
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# Posted: 25 Jan 2014 16:39
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The only materials I could find that meet the 15 minutes are cementious or non-combustible. I think I'm going to have to throw a layer of 1/2" gyp on my roof under the polyiso. Another $100.
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creeky
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# Posted: 26 Jan 2014 09:26
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Foams have a lot of embedded energy. That's for sure. But it would be interesting to test foil covered polyiso vs t&g painted with polyurethane/shellac. Esp. after the t&g has aged a few years.
http://c.ymcdn.com/sites/www.polyiso.org/resource/resmgr/technical_bulletins/tb104_ju n30.pdf
is a "fire performance of polyiso in roof systems". They speak very highly of the material. bldginsp you might want to have a look.
also:
"Polyiso passes both the ANSI UL 1256 and FM 4450 fire tests without a thermal barrier. Polyiso, a thermoset material, stays intact during fire exposure in the ASTM E84 or "Tunnel Test." It forms a protective char layer and remains in place during the test, thereby meeting all building code requirements and contributing to a fire-safe building."
http://www.polyiso.org/?page=FirePerformance
apparently 60% of all commercial buildings are now insulating with polyiso.
what I like is the material is fairly easy to source as a recycled / used material and for the money offers tremendous insulating value.
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bldginsp
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# Posted: 26 Jan 2014 16:04
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Creeky-
I got all my polyiso for my cabin roof from craigslist, at half price or less. I had to watch for a while, but it came up.
Yes I've seen a few references to how polyiso seems to be a lot better than polyurethane foam in fire situations. All of that info, though, that I've seen, comes from the manufacturers themselves. They are hopefully right, but we know where their motivations are. Not sure where to go to get an objective look at this.
But I think I might throw a layer of gyp on my roof under the polyiso anyway, just for peace of mind. When the stuff does burn, it produces CO and cyanide gas, not a pretty scenario.
Thanks for the links
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creeky
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# Posted: 26 Jan 2014 21:34
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This is an important topic for me so I'm happy to hash it out.
I've bought almost a hundred sheets of polyiso so far. when I get to year three on creeky's camp build you'll see I've built one of my out buildings (ah the noble shizzer shack) almost entirely out of polyiso. used and new. the ease of installation. the high r value. the amazing ventilation/heating systems you can build with it. the low cost. it rocks.
and that it does meet ansi ul, fm and astm standards and is approved by code is important ... that's about as objective and realistic as we're going to get.
in perspective: it seems all combustible materials that contain nitrogen create hydrogen cyanide. so. wood. not to mention laminate flooring/cabinets. glues. furniture (filled with polyurethanes). etc.
According to the literature I've found, your biggest concern in any fire is CO. I mean we don't have to fight the fire. we just have to get the bleep out.
imho. twice warned and all that. there is no substitute for smoke/gas detectors. planned and practiced emergency escape routes.
of course. my biggest building is 12x20. It's two steps to being outside. i practice hasty exits a dozen times a day. those with larger buildings and longer exit routes being taken by less capable legs ... may have other thoughts.
and I have smoke/co/gas detectors everywhere. for 60 bucks ...
I would like to see a drawing of your roof. I don't see what you're saying. why would you put an additional fire barrier in an area, usually free of ignition sources, that can't contaminate your living space? In a high ventilation area like that I would think CO and HC would be low risk factors?
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