Inspector says NO WAY to rigid spray foam under roof deck due to fire code–isnt’ that application pretty widely used?
A high-performance single-family home builder shares tips from his early experience with two apartment buildings.
"I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.
Dig into cutting-edge approaches and decades of proven solutions with total access to our experts and tradespeople.
Start Free Trial NowGet instant access to the latest developments in green building, research, and reports from the field.
Start Free Trial Now
Replies
Inspector is correct - the foam needs substantial protection from fire. This is usually provided by two layers of drywall.
It cannot be stressed enough ... foam insulation is made from petroleum ... expect it to burn like it!
The manufacturers' instructions for installing foam are quite clear on this point. Foam, especially when installed overhead, needs lots of fire protection.
renostienke,
check the regs, type X sheeetrock is usually the approved requirement for fireproofing requirements in over head application. Home Depot sells type X for only a little more than regular sheetrock. (about 60 cents a sheet last I looked)
second
Check you information regarding foam, most foam will burn when exposed to a source of ignition but will self extinguish.
Regular readers of this forum have been around this bush several times already..... Whatever the claims of the manufacturer as to the 'self extinguishing' or 'fire retardants' in their product, ALL currently produced foams fail miserably in industry standard fire tests. "Rocket fuel" is one of the common terms used to describe the burning characteristics. Likewise, a common manufacturers spec for foam installed overhead is that it be protected by a 1-hr rated assembly; this most often is accomplished by double layer of 5/8 drywall. So, it's not unreasonable for the inspector to want such protection for the foam. Time to get an architect to sign off on the plans.
So, it's not unreasonable for the inspector to want such protection for the foam. Time to get an architect to sign off on the plans.
I am also in favor of not having a fire reach my living space without a fair chance to escape, so I am happy to meet this code. I would rather use an approved single layer of drywall than 2 standard layers, so I will check with the inspector to see if that will satisfy.
Thanks for the comments--when I did an advanced search for foam I found so many posts that I was going cross-eyed looking for everything I needed. Initially I was looking for (and found) info on spraying under the roof deck and not venting vs. venting attic and spraying the attic side of the ceiling. After reading the posts, I opted for teh former and ran into the code issue...
An architect drew these plans, but I don't know what it means to have him "sign off" on them...
By "sign off" I mean a set of plans, with his stamp, that has been submitted through plan review ... and approved. To a large extent, the inspector does little beyond verify that what the architect drew is what the contractor built. For example ... if the architect specifies one layer of rock, one will do. If he spec'd two layers, then you need two. Etc.
renosteinke,
Nonesense!
I had plenty of chances to test my foam's fire resistant properties.
One of the tools used with SIP's is a melter which looks exactly like a bent barbeque fire starter. What you do is heat this thing up and carve out foam to allow for making custom fitting panels.
You melt the foam out.. it gets glowing red hot. Eventually if connected long enough it's possible to get the foam to burst into flame.. to extinguish you simply remove the source of the ignition from the foam.. the flame goes out by itself or a quick puff from the worker blows it out even quicker..
I used that same melter to remove foam from my sisters house,, she had a stick framed house with foam sprayed between the studs.. one area was sprayed but the excess foam had not been cut away.. when my sister was finally ready to sheetrock that I gave her a hand and showed her how the melter worked in tight areas where we couldn't get a sawzall blade into. eventually glowing red hot we got the foam to burst into flame.. however the flame wouldn't spread and eventually died out on it's own..
I'm sure that if you put fiberglas to the same test flames might spread and while celluliose has flame retardant in it like foam it too can burn in roughly the same manner.
It's really not a matter of opinion. Building assemblies, and their parts, are subjected to standardized tests. These tests often are defined by an ANSI standard, and manufacturers' results are verified by independent labs, such as UL or FM. One of the challenges in "fire science" is developing tests whose results are comparable to real-world fire results. That's the problem with so many of the 'matchstick' tests folks do .... the results do not mirror what happens in real fires. I have performed these tests, on both production materials and experimental mixes. I am well aware of the various attempts to make the stuff less flammable. All the special additives ever seem to do is make the resulting smoke and ash even more noxious than it already is. None of them have made the slightest difference in the tests. Oddly enough, there once was an essentially fireproof foam available; it fell victim, IMO, to one of the earlier environmental junk science lawsuits. That many builders seemed to have disregarded manufacturers' instructions didn't help matters any. Opinions are a lot like fingers ... most have a couple handfuls of them! Facts and data are another matter. There's a reason the manufacturers have the instructions that they do.
reinstienke,
I gave you facts. You choose to ignore them and fall back on your sources,, if I had the inclination I'm sure that I could find the tests and such which support my position.
Let's see where we do agree,
first fire is dangerous and in a fire many things which are not rated will burn and provide dangerous levels of smoke.
2nd Any insulation should be covered..
3rd building codes specify exactly what is required in given situation..
Now where we disagree. you call foam a rocket fuel and I say that foam that the foam I've used and my sister used is self extinguishing..
How do we resolve that? lighters at 20 paces? ;-)
Resolve it with the "Steiner tunnel," the test method described as ASTM E-84.
renostienke,
you bring the tunnel I'll bring the foam. if you want I'll even bring the fiberglas or celluliose..
Save yourself a trip ... I believe the info for all of those is on the UL web site. FG essentially no flame spread. Foam off the scale. Even the foam with "low" ratings comes with a caveat that boils down to "product cheated, and gave misleading results - bury under lots of drywall!"
renosteinke,
let's see they conformed to the UBC requirements and that's some how cheating?
I'm sorry but I haven't memorized the new code to recite chapter and verse.. it's been years (decades) since I was a fire fighting instructor but I am fully aware of the danger of fires and that danger was resolved completely before I decided to use it in my home..
There are millions of homes out there with foam in them, either they are all wrong or perhaps you aren't fully aware of the correct information on the subject..
besides, if a fire starts in a house the burning of the insulation is a tiny fraction of the smoke created.. furniture matteresses, rugs and thousands of other items create far more smoke and fire danger than insulation..
Your focus on one item cause me to question your subjectivety on the subject..
No, they did not conform .... the nature of the product interfered with the test, causing it to appear to be far less flammable than it was. The "tunnel" has a massive flame at one end, with a strong draft, and the sample place on the top of the tunnel. The idea is that the flame will light the sample, the draft will move the burn along, and products can be compared by how fast the flame moves the length of the tunnel. Foam samples, as soon as they are touched by the flame, fall to the floor of the tunnel ... where they burn with great vigor. The forced draft, however, acts as a barrier, preventing the burning foam from igniting the rest of the sample. Full scale testing, where the foam is installed in actual walls and ceilings, confirm that unprotected foam burns like gasoline - or rocket fuel. It also puts out about double the heat that a similar amount of wood or paper generates when it burns - a heat output again consistent with petrol. Finally, the smoke generated is amongst the nastiest of any product, and there's lots of it!
renosteinke.
That's pure bullship..
where to begin!
OK let's start at the heart of fire,
it takes three things to have a fire.. heat, fuel, and oxygen
cut off any one of those three and you don't have a fire.. pure and simple!
Fiberglas insulation is real good at providing all three..
It's a poor thermal barrier( it's is used in furnace filters because it flows so much air so freely) and it can burn providing fuel..
Same with celluliose..
While it's a superior thermal barrier, less likely to provide massive air movement, and usually treated with a fire retardant it too is capable in the right circumstances of burning..
Foam on the other hand is superior as a thermal barrier, thus less likely to transfer heat, air proof (if you doubt me spray some in your throat) ;-) and fuel...Like celluliose foam is treated to not be a fuel.. like celluliose it will burn but remove the ignition source and the fire will expire..
All I've done is explain the facts, as developed through repeatable experimentation, testing ... and verified by looking at actual fires. This body of information has been accumulating at least since WW2, and the work continues daily. Many, many code requirements were influenced by these tests. Everyone has opinions .... when you have data, your opinion gets noticed.
2006 IRC allows for 3/8" sheetrock or 1/4" ply as a thermal barrier over foam in an attic space.
I'm not sure which code you fall under or if your fire code supercedes building code.
OP-
did the inspector show you the section of the code he was referring to? Or- more than likely simply talking out of his azz?
Code here is 15 minute thermal barrier coverage. That is 1/2" sheetrock, or equivalent.
PS. Love you Frenchy. Keep up the good work.
He did not specify the code, but we decided to spray 8" of open cell on to the top of the ceiling drywall instead and vent the attic. We have no mechanicals in the attic space and it is about 2,500- less costly since we have a steep pitched roof and spraying the roof deck was adding up dollar-wise.
In many areas you can also spray an intumescent paint over the icynene instead of drywall. We've used FF88
Barry E-Remodeler
that makes perfect sense to me. Good job.