Icynene + wood ceiling a fire hazard?
Howdy all;
We’re currently prepping the underside of our roof sheathing to have 5″ of Icynene sprayed between the upper trusses. After that we plan on covering the icynene with car/barn siding and voila – there’s our ceiling.
Recently my wife’s uncle told her that we couldn’t do this as it was a fire hazard. I know that Icynene can be consumed by fire, but that it isn’t a fuel for fire and won’t continue to burn if the source of the fire is removed. What I don’t know is whether the wood siding planks we’ll be putting up to cover the upper trusses and icynene foam will be acceptable based on Building Codes, or just a general safety standpoint.
I’ve seen a number of car-siding ceilings, and in talking to the folks that built them the issue of fire resistance never came up.
Have I missed a really big consideration? I’d like to sound a little smarter next time I run into this uncle (so he doesn’t worry that I’m going to kill his niece with shoddy craftsmenship… =)
Thanks for any help.
banned from the nail gun
Replies
The whole thing is flammable, what's he talking about the siding or the foam or the trusses?
Joe H
Who knows for sure. My best guess is that he's unaware of the burn properties of Icynene - it seems to behave pretty benignly as far as I can tell. This coupled with the fact that I'm wanting to build a wood ceiling has my wife thinking her dumb husband is building a fire trap. It's kind of frustrating being second-guessed without having been around for the initial conversation.All that being said - am I creating an enormous fire hazard? The roof sheathing, trusses, and everything else up there is 100 year old wood - I don't imagine any of it's too fire resistant to begin with. I just don't want to make it worse.Argh.------------------------
banned from the nail gun
He might be thinking of sprayed polyurethane.
Poly has a significantly higher smoke development.
Terry
Sprayed foam insulation burns like rocket fuel; it's not to far from the truth to describe it as "solid gasoline."
This is why it is always- and especially when mounted overhead- recommended to face it with at least 5/8 of drywall.
There is no reason that you could not face the drywall with wood, though, to get the look you desire.
Are you the same one who used the "Rocket Fuel" statement a few weeks ago until a third party stated that he tried burning it and he couldn't even get it to burn? Please post pictures of this "Rocket Fuel" you've seen. We would all love to see the evidence. Stu
Yes, I am the same person. Despite the assertion of that other person, and their completely unscientific "test, I stand by it. The industry standard fire tests bear me out. Indeed, it is these very tests, which I have performed and witnessed, that are the basis of my opinion. As mentioned back then, some foams are marked with deceptively low flame spread ratings- deceptive, because they take advantage of a quirk in the testing arrangement.
As I have personally witnessed, numerous times... I don't care how many "flame inhibitors" are added to the mix- the stuff still burns with great enthusiasm.
It also generates a particularly nasty smoke- one that is far more irritating that even the "smoke generated" numbers would lead you to expect. No need to accept my word for all of this; feel free to check with either UL, or the manufacturers. All involved are quite strident: They would greatly prefer you never mount the stuff overhead.... insist it be protected by drywall or other fire-rated material... and double that if you simply must place it above you!
hey reno;
While I appreciate your thoughts, I think you're making some pretty unfounded claims, at least where Icynene is concerned. Like someone mentioned, perhaps other types of foams are guilty of being really combustible, but I just spent the last 15 minutes trying to get a chunk of Icynene to act like solid gasoline. It turns black and shrinks, and puts off an odor that approaches old moth balls, but it doesn't carry a flame and produces little smoke. This confirms what other sources (both the icynene web site and unrelated insulation/construction web sites) also say.Again, I appreciate anyone's ideas, but get your facts straight. If you're not careful someone might take you seriously... =)For anyone interested, Here are some before, during, and after shots of my unscientific burn tests. The last one I'm pulling away the flame, and the foam has no flame of its own - just a wisp of smoke.http://www.eyepulp.net/photo/misc/burn1.jpg
http://www.eyepulp.net/photo/misc/burn2.jpg
http://www.eyepulp.net/photo/misc/burn3.jpg------------------------
banned from the nail gun
Perhaps I am confusing the stuff with something else... what does the UL label say? It should have both a "flame spread" and "smoke generated" rating. The clever way this stuff fools the test is, as you described, by 'shrinking away' from the flame. It also will fall away from he remaining insulation as it nears ignition. This is the effect of the "flame inhibitors" added to the mix. Put the stuff in the "Steiner tunnel" (the apparatus for measuring flame spread), and a different result is discovered.... the stuff near the flame falls to the floor of the tunnel, where it burns with great gusto, giving off lots of heat, flame, and smoke. However, the great amount of air that is forced through the duct during the test does a fine job of keeping these flames from igniting the rest of the sample. So the stuff gets a 'flame spread' rating that looks like "fire resistant," but really isn't.
reno;
Thanks for taking the time to clarify some of your comments. I think your point is well taken, as far as why it's bad for foam to burn in a certain way, as well as why current testing doesn't seem to catch it.That being said, one of the great selling points of Icynene is that it doesn't react like other foams to fire. It turns to ash and indeed smells, but it doesn't sustain a flame on its own. It's not a fuel source. This seems borne out the testing (real testing, not me and a lighter =) I've read on it - not just the spread ratings, but burn characteristics. Again, I can't speak for other foams, though I've definitely heard some of the horror stories.All this being said, I'm looking into a sprinkler system to make this a moot point from both a safety and code compliance standpoint. =)------------------------
banned from the nail gun
EyePulp - I'm not sure where you're located, but in some locales Icynene recommends a vapor retarder applied to the warm side. In some locations latex paint is sufficient but you should talk to their home office. They were helpful the one time I talked with them.
I can't answer your building code question but if you need to cover it with something you may be able to deal with the moisture concerns at the same time.
Best of luck.
hey grandizer;
I'm in central Illinois, US. According to what I've seen and heard from people in the area, a vapor retarder isn't needed on the foam. But the idea of being able to paint on or spray on something to produce the fire retardation is appealing. The ceiling's about 30 feet in the air, so if it's on fire then the rest of the building is probably already in cinders, but hey, if we can meet code, then I guess I'm not going to complain too much.Does this mean people typically have something between wood ceilings/paneling and the stud bays and insulation? Or do they just use a treated wood of some sort?To all:
Thanks for your help - this seems like such a basic issue, but like everything, there's always more to it.------------------------
banned from the nail gun
Don't trust the Icynene dudes for advice: follow the local building code. In my locale, open cell foam insulation like Icynene MUST be covered with a vapour barrier. Icynene meets the requirements of an air barrier, but NOT of a vapour barrier. Closed-cell foam (Corbond polyurethane etc.) does not require a vapour barrier.
Also, read my thread and make SURE you are covered in the event the Icynene guy screws up like he did on my place. It's been almost eight months since he sprayed my garage/shop and you can STILL smell the excess resin out-gassing through the layer of foam he sprayed over it, even with an intact vapour barrier covering the finished foam. And no action from the b*stard either- I'll have to take him to court to get anything out of him.
As to the fire concern: both wood and the foam are combustible. Based on my own experiments with icynene scraps, I can verify that it does not behave like "solid gasoline"- it's nowhere nearly as flammable as, say, polystyrene foam- that stuff burns like a b*stard. But Icynene appears to be no less combustible than wood, so it's far worse than, say, fibreglass or mineral fibre insulation from a flame spread point of view. A layer of drywall under the finished board ceiling would buy you time in the case of fire, and may make the difference between a fire leading to smoke damage and one leading to a total loss of your structure. But unless you have a fire which reaches the ceiling, it's all a moot concern. If you're concerned about having a structure which will survive fire and firefighting without major structural damage, build with concrete! Otherwise, install a sprinkler system- that will make more of a difference than drywall would, and will also usually reduce your home fire insurance premiums as well.
A sprinkler system? Now you're talking! That makes tons more sense than simply trying to slow the fire down. It just might be cheaper and easier to install than an additional layer of drywall too - though I guess a layer of drywall wouldn't need to be pretty or finished since it would be covered by the wood.Good ideas.------------------------
banned from the nail gun