I reframed a six family house this past summer, the loss was do to a fire.
We used 32′ I-joists for the flat roof.
Needless to say two weeks ago someone torched it again.
The point is. When I got there to see the house, I was amazed how easy the I-joists burned.
Had there been 2×10 or 2×12’s, would that whole roof be gone?
Me personally. I don’t think so. I think the thought of these I-joists are fine for what we use them for but as far as fires are concerned, I think we have a serious problem.
This is the first fire job that I have done in 12 years that was burned down again and to see the I-joists was scarey.
I would like to bring this up at a seminar.
Any thoughts.
Joe Carola
Replies
Joe
Course it burned. Lotsa glue in dem joists. What else would you have used anyway......2x stock? That would burn just as easily. Thing that might be of interest would be .....since they manufacture these things. ....why not fire proof em. The added cost would be worth it. Then again why not fireproof the plywood? Reckon they dont figure people are gonna torch things on the whole. If you used steel I-beams then that'd be standing..so what.everything else'd be a marshmellow roast.
Be burnt
Namaste'
Andy
It's not who's right, it's who's left ~ http://CLIFFORDRENOVATIONS.COM
Andy, actually, steel fares much poorly in a fire than 2x dimensional lumber. I'm not sure of the comparison of I joists to steel, though.
Framer, if it's that big of a deal, use 5/8 type x rock wherever you want and install draftstopping. I would take that alternative (done well) over a factory fire proof.
Jon Blakemore
Jon,
We actually did something to that effect that about 5 years ago. The beams sat up on abouit a 2' kneewall above the ceiling beams and every 4' we had to run 3/4" plywood from the top of the I-joist down to the top of the ceing beams across the whole width of the building.
In my mind for years it just seemed like common sence that they would burn quick just never thought about it until I seen it.
Joe Carola
I'm more concerned about the scum that did it. I already know that plywood burns hot and fast and thin wood burns through faster than solid two by dimension lumber.
But arsonists are cowards and perverted. How many fingers should we cut off?
Excellence is its own reward!
"The first rule is to keep an untroubled spirit.
The second is to look things in the face and know them for what they are."
--Marcus Aurelius
Piffin,
Cut them all off but the thumb. That way they would still try to grab things and get real mad. Remember that Mike's hard lemonade commercial where the guy loses his hand and then goes to the bar. The bartender slides the Mike's down and the guy reaches for it but can't grab it. He's got no Hand!!
Piffin,
I'd say we cut off both his hands. If he gets caught he'll probably get a slap on the wrist like everyone else in this country does.
The first time they torched the house the people were home.
My friend is the GC on the job. I feel bad for him because his mother past away and he went back to Greece and this happened while he was out there.
He was 2 to 3 weeks away from completion of the job.
These houses are set up where their only 6' in between eachother.
Luckily only the siding burned on the house next door.
On the third floor there was 27 spots where they said that they cut small holes out of the sheetrock and poured gasoline and then used a torch.
Now we have to do the job all over again.
Joe Carola
Use neither, timbers! That's the answer! If a TGI burns thru in 7 minutes and becomes weakened in 4, then a 2x's will burn thru in 12 and weaken in 7. however a timber will take more than a half an hour to burn thru and 20 plus minutes to weaken.
Doubt me? Look it up in the UBC.
Frenchy,
Sounds nice, but I guess will have to tell that to all the architects and engineers.
Joe Carola
Joe,
I joists are part of a system and it's kinda unfair to use just plain wood as a burn rate. Properly installed sheetrock will provide a decent firestop probably enough to make the differance.
On the other hand I can put a 6x 9 in the fire for an hour and pull it out and still have enough strength left in it to walk acroos the room on it.
after an hour in the fire place I'm not certain I could evan find the ashes of the TGI
"Properly installed sheetrock will provide a decent firestop probably enough to make the differance. "
It won't make any difference when they cut holes in it and pour gas into the cavities.
Maybe I'm not able to look past the end of my nose, but I don't think we should design our buildings with the assumption that someone will try to burn them down.
I could easily damage a car very seriously (even sabotage that is likely to injure the occupants) with just some wire cutters, but that doesn't mean that we should desing our cars accordingly.
Maybe I'm just being naive...Jon Blakemore
2x's will burn thru in 12 and weaken in 7.
Man Dear alive. You must plane them awful thin down your way.
Doc - The Old Cynic
Take a 2x and toss it on a roaring fire. Seven minutes later pull it out and compare it's strength. Now toss a 2x into the same roaring fire and see how long it takes to burn thru it.
There really is no way to accuritely measure the exact strength of a 2x since so there are so many variables. Moisture content for one. A new board has 19% moisture +or- an older board might be 7% or less. Doug fir burns at one rate, pine another and the "western white woods who knows? One board may be full of pitch and very fast growth and another pure heart wood from old growth.
When I was a fire fighting instructor I used to read some of the fire death reports to my class. It was amazing how many reports commented (in a seemingly positive way) at how new and well maintained the building appeared. Yet talking to some of the old timers who'd been around for a long time they felt safer going into turn of the century buildings than they did new ones...
But arsonists are cowards and perverted. How many fingers should we cut off?
They're Aries's Piff. they cant seem to help themselves. You from the far east in a past incarnation or sumpin bro? Cut fingers off? Perverted aint about fire its about pouncin' lil' kids and the such. Seems yer in a bad day bro. Save the sarcasm for me .....you're too upper echelon for that stuff...lol
Be a wall
Namaste
andyIt's not who's right, it's who's left ~ http://CLIFFORDRENOVATIONS.COM
Steel heats...bends..and fails.
Wood....burns....and chars...which protects the rest of the wood.
Frenchy's right....big timbers don't burn thru.........right away.
I'd guess that the wood I's burn thru lots quicker than dimensional.
Know for a fact that that a beam for the same size load......wood will out last steel in a fire.
JeffBuck Construction Pittsburgh,PA
Fine Carpentery.....While U Waite
Jeff
Pretty cool (hot) thread. Is this a fact? I kind of understand the concept but not sure I belive it. The fires gotta be pretty rip roarin' hot to have the steel fail. Right? So whats the time frame of failing steel next to wood? I kinda dont believe that theory. We talkin World Trade Center Vs a residential house or what? I find it unfair to make that statement without comparing apples to apples.
Be a wall
Namaste
AndyIt's not who's right, it's who's left ~ http://CLIFFORDRENOVATIONS.COM
The way that steel fails and wood fails are different because of the composition of the materials.
Wood is long fibres twisted together. It will fail by degrees. A wood framing member will gradually sag, splinter, twist and groan long before it's eventual collapse. The fire that chars without consuming will also harden. Heat that consumes wood, breaks it down to simpler elements and compounds - mostly gases.
Steel is more of a crystaline material. It's internal makeup is more like a brick wall stacked with weak mortar. when it fails, it happens suddenly, buckling with little warning. Heat will change the structure of steel without consuming it but an intense fire changes some of it to the liquid state.
The process of failure in the two materials is different..
Excellence is its own reward!
"The first rule is to keep an untroubled spirit.
The second is to look things in the face and know them for what they are."
--Marcus Aurelius
I once saw a picture in a carpentry textbook that was demonstrating this principle. It was a commercial building with steel bar joists resting on a wood glulam. The steel looked like a bunch of wet noodles, all twisted and sagging, on the wood member which was charred but not too bad. Granted (this is for you Frenchy) the glulam was probably something like an 8x24, but I could imagine that 2x10's still have a significant advantage over steel.
Another issue I just thought of, steel conducts something like 300 times better than wood. The heat in one general locale will quickly spread (possibly even from joists to plates to studs etc.) and break down the whole member much more quickly than a localized fire would affect wood.
Jon Blakemore
No sarcasm, Andy. Just cold hard facts.
It's well over 90% of arsonists are doing it for the pure pleasure. And a devient pleasure it is. Most have some history of abuse as a child and of deviant behaviour in other ways than just torching. Few women do it and the greatest portion of the men who do have trouble experiencing sexual relations with women.
Now take the definition of perverted.
Not the vulgate version. The actual definition of the word.
Does not an arsonist deviate from the norm? That makes him perverted in his passions and actions..
Excellence is its own reward!
"The first rule is to keep an untroubled spirit.
The second is to look things in the face and know them for what they are."
--Marcus Aurelius
I asked an I-joist salesman once if he had any information about I-joists and fire. He told me the best thing to do if customers brought it up was to change the subject and/or avoid talking about it.
I know there have been tests so I-joist assemblies could get one hour fire ratings (Or whatever - Don't remember exactly) But I have no idea where to find the info on those tests, or even who exactly it is that does them.
I do wish the I-joists industry was more upfront about the issue.
A side note to Frenchy - I know you like timber framing, but it's hardly practical for mainstream building. Takes too much large sized lumber that's not readily available.
Asking me about analogies is like... okay, I may be the wrong man to ask. [John Laroquette]
Boss,
I bring this up only because it was always a thought or a conversation over the years amongst other framers and builders.
I've done alot of fire jobs over the past 12 years and to actually see I-joists burnt for the first time just answered all my thoughts and questions comparing it to 2x's when burnt.
If a 2x is charred more than 1/8"- 1/4" we have to remove it. I'm sure when we start this job over again the slightest bit charred on the I-joists plywood we would have to remove the whole beam.
We'll I was thinking, It's probably worse using a Parallel- Chord Floor Truss, there's no plywood or solid 1-1/2" material.
Maybe like what Frenchy says about using timbers. We should start using 5-1/2" x 9-1/2" or 5-1/2" x 11-7/8" beams for our floors ;-)
Jon, I understand what you saying about them not designing houses so people don't torch them but once the fire gets through the fire rated 5/8" sheetrock if it were my house I would rather have 2x 's intead.
Joe Carola
While aspects of the need for greater framing member replacement may be higher with I-joists when compared to 2by framing and as person in a building trade this is interesting my greater concern is for safety. Both the occupants and any emergency personnel depend on the framing remaining structurally sound enough to allow escape or rescue. I'm not convinced that exposed I-joists, as presently manufactured and installed, pass this minimum standard.
In another post I suggested that a coat of intumescent paint, a paint that puffs up and forms an insulating char when heated, may provide an affordable solution. The paint is cheap, easily applied with unmodified rollers or sprayers and fairly effective. Once painted the I-joists could be installed in the same way they are presently.
Some have touted the relative survivability of timber framing. The larger bulk of the members takes a fire much longer to reduce its strength to hazardous levels. This effect is even greater if the square edges are rounded over. Many industrial building had exposed beams with a good 3/4" round that limits the ability of fire to catch.
All this bodes well for timber framing. I do like the look and feel of timber framed buildings but have my doubts about the real environmental friendliness of the method. Smaller framing members can be had from smaller, faster growing, trees. I joists make the most efficient use of wood both from a strength to material used basis and energy used in shipping. The counter claim is that timber framing promotes management of forests to produce larger trees. The problem is that while most timber framing comes old growth forests there is little rebound to move forest, once cut, away from toothpick factories, tree farms, to forests sustainably producing large diameter trees.
I like I-joists for their efficient use of a cheap renewable resource and ease of installation and think that, with some mitigation of their frailty when exposed to fire, they will continue to expand their market share. Intumescent paint is just one idea and may not be the best answer.
4Lorn1
Not to get off my subject but were you ever an English teacher? LOL
Be a wall
Namaste'
andyYou don’t complete your inner work before you do your outer work. Nor do you say, "Well, the hell with the inner work: I’ll go do the outer work because it’s so important and pressing." That’s not conscious either. The conscious thing is the simultaneous doing of both. "Ram Dass"http://CLIFFORDRENOVATIONS.COM
No. I'll take that as a compliment. Thanks.
You make a good point about using less expensive (shorter growth cycle) than timber with TGI's However it depends on two major factors.
First,
Construction details. Is the home built in such a manner that it is likely to be structurally sound for a long time?
Second,
Suitablitity,
Is the home of such a design that it with be useable for a variety of needs?
Someplace I read that the average house was 56 years old prior to it's demolution or total gut. Since some of the douglas firs that it was built with took a thousand years or more to grow it's obvious there is a problem.
My timberframe has some old growth oaks that were alive before the Declaration of Independance was signed. To make the use of such wood proper and sustainable I built it not for the typical 20-30 years but rather in a fashion that the Europeans did where homes lasted over 500 years.
Now there is real cost to such a decision but hopefully given time This house will justify that time and effort...
Do I for one moment suggest that this course is the proper one? NO! Indeed not! (it's said the average American lives in one location less than 5 years) Perhaps TGI's are all the typical American needs.