Read recent notes on benefits of I joists vs 2xs. As a fireman the standard rule with I joists is to retreat to an exteror attack as soon as humans are out of the building. I-joists burn through too quickly and bring danger of sudden failure. Result is I- joisted buidlings likely suffer more damage then an equal 2xs construction.
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half of good living is staying out of bad situations
I'm getting the hell out during the fire either way.
After the fire i'm fixing/replacing anything that is affected to a point that it is as good as before - that's why I pay ALOT of money for insurance.
I understand your concern - as a guy in the fire - but it doesn't effect most people.
When my agent charges more for one type of construction vs. the other then I'll care.
Structurally either way is adequate.
In your own post you stated that when you encounter i-joists,you only fight from a distance.
It looks like a self-fulfilling proficy.
Remodeling Contractor just on the other side of the Glass City
Just commenting that all things being equal an I joisted house is likely to suffer more damage due to fire fighting constrants. Cardinal rule is risk assestment to fire fighter injury and due to rapid I beam failure means quicker move to exterior defense with attendent higher damage.
erik111
I agree completely with your thinking.. If you go into old timberframed warehouses after roaring raging fires you'll often see the building still standing and the timbers needing little more than a sandblasting to be made reusable.. That's why the UBC doesn't have a fire rating for larger timbers! It takes too long to get them burning and they burn too slow to weaken..
Now if America would just adapt European firecodes with regard to the pegged connections we are sooo much in love with large timberframed buildings could be rated along with masonary buildings for fire purposes..
Just for information the eurpoeans require a steel or metal connection thermally insulated.. What that translates into is a steel bar or bolt with wooden pegs coverings simulating the "look" of of traditional pegs..
The weakest point in traditional timberframes is the connections.. those pegs burn thru and the post falls down. By using thermally insulated metal fasteners that possiblity is avoided..
But more closley to your point it simply takes longer for a solid wood joist to burn thru and weaken than it does a I joist. In addition the adhesive has an operating tempurature. when that is exceeded as in a fire the flakes of wood fiber expose their thin edge to further flame and more heat resulting in quick delamination and failure. Try to light a log with a match. can't be done.. the thermal mass prevents ignition.. However a thin wafer of wood fiber is easy to ignite with a match and that causes the adhesive to fail exposing more fiber edges etc..
I was going through the latest FH and I saw a section where they said that I beams -steel - will not hold up as well as 2x lumber, resulting in a greater catastrophic failure. I have no experience at all here, but this seemed really surprising to me.
Any thoughts or experience out there from firefighters? Care to explain - or disagree?
Don K.
EJG Homes Renovations - New Construction - Rentals
That's because heaat will contribute thermal distortion to the steel far sooner than it will burn the strength out of a solid joist
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
It's also because "we" aren't allowed to spray on that 1-1 1/2" thick coat of absestos-modified celulose on the exposed steel. That treatment added hours of full fire exposure ofr "red iron."
That's life though, things change.Occupational hazard of my occupation not being around (sorry Bubba)
Around 1200 degrees steel turns into spaghetti. At lower temps it elongates, and steel beams in pockets in masonry walls have been known to elongate enough to push the wall down during a fire.
I think that's a gross over-generalization. What size of I-beam are you going to compare to what size of beam made from 2X material? The thickness of the flanges on the I-beam and the number of plies of the 2X beam would all affect how they performed. How would the fire attack the beam? (Every fire is different) Are you comparing a fire from below, or one that starts above the beam?I just don't tyhink it's that simple....
Aren't all generalizations false?
Boss -
I haven't worked on any fire jobs that I recall with steel beams that failed. I don't know how much fire it takes to generate 1200 degrees of heat, or what that same amount of heat will do to a laid up 2x10 (for comparison).
I started to read your thread on fires and trusses, and hope to finish it soon. I do find it interesting. My buddy is a fireman for 40 years, I will talk to him tomorrow.
Don K.
EJG Homes Renovations - New Construction - Rentals
PS.: By the way, I was thinking about Laurel the other day.. Post.#74264.3 Pumped for the Fest
I've never actually seen a steel beam that was in a fire either. I was only pointing out that I didn't think it was a simple comparison. There are just too many variables. I don't think 1,200° in a fire is very much at all. One point to consider is that while a steel beam may not last longer in a fire, it also doesn't contribute and fuel to a fire.
I'm not your type. I'm not inflatable.
As has been pointed out in similar threads, the deficiencies of i-joists could be ameliorated with intumescent paints.People have to get sufficiently educated about fire safety to get past the laughing point at the idea of painting joists.I suppose we'll have to wait for a big headline-making fire with lots of kids killed......
"I suppose we'll have to wait for a big headline-making fire with lots of kids killed......"
I've never heard of a case where structural collapse of a roof or floor member kept any occupants from getting out of a burning building.
By the time a fire has progressed that far everyone inside is already dead.
The only good loan is a paid loan
Hey Boss,
Thanks for all your input/info, this is an understated and little known area of expertise and I find it great to know the opions and views from around the country on this subject.I myself have thought about this in passing while watching a plumber burn the cr@p out an I- Joist sweating copper on a build. I have a few firefighter friends who are concerened about it and the biggest challenge being, which houses have I joists? Protocol is being discussed by head chiefs and building dept. on this from what my buddy says. The biggest worry is actually the steel framed tract homes! Sumarising his expaination: A first floor fully involved fire heats up the steel studs, the cement board siding seems the retain heat inside the building envelope trapping heat. Studs turn into rubber bands and seemingly premature colapse of first floor even before second floor is involved. Point: Most bedrooms are on second floor= difficult manual attack for survivor search, time is super critical! Here, there are many new developements with barely legal fire lanes and many,many cars parked on side of streets making for difficult access in the first place so a ladder truck or even engines have a difficult time. Along with neighbors wanting to save thier vehicles and choking the streets. He described a five block dash in full bunker gear with a roll of hose and ladders, etc... because of this. There are many factors that contribute to failure and possible loss of life. A fire resistant glue, coating maybe? could give those extra minutes for a rescue. Burn through is a problem that should be addressed and I hope some I joist mfg. guy is reading this thread. It only takes one highly publicized incident to bring this to a head, lets hope it doesn't happen that way before someone get smart.__________________________
Judo Chop!
I had kinda forgotten about this thread until I saw your post. But I did a thread once called "I-joists roasting on an Open Fire" that might interest you:http://forums.taunton.com/tp-breaktime/messages?msg=37987.1I don't look for any coatings on I-joists anytime soon. The manufacturers would likely be willing to do it, but people simply aren't willing to pay for it. In the talks I've given to fire departments, I tell 'em not to expect any changes. The public just doesn't care about firefighters and their problems until something big happens. One of these days if some cute blonde firefighter with big boobs gets killed then everyone will be screaming that something should have been done to prevent this, etc. The politicians will sieze on it and maybe try to pass a law or two. Then the public will quickly forget about it and move on to something else. .As I said before, I don't think I-joists and occupant rescues are an issue. By the time the fire has progressed that far any occupants would already be dead from smoke inhalation. I've read a lot of fire reports, and have never heard of a case where any kind of structural collapse kept occupants from getting out or being rescued. To me, the solution is to quit risking human lives to enter unoccupied buildings to put fires out. But when I tell firefighters that, they don't want to hear it. One firefighter told me: "That wouldn't be any fun".So basically I don't figure much at all will change.
The biggest worry is actually the steel framed tract homes!
Sumarising his expaination: A first floor fully involved fire heats up the steel studs, the cement board siding seems the retain heat inside the building envelope trapping heat. Studs turn into rubber bands and seemingly premature colapse of first floor even before second floor is involved.
Which is an interesting supposition. But, not one I'd really worry about in some ways.
If we presume an all galvanized stud construction (not a pipe frame with metal stud infill--that's slightly different), there really plenty of evidence out there from commercial construction. You'd have other problems (like flashover) well before you get soft studs. Don't forget that the exterior walls are filled with "something" (ok, it's tract builders, it's the cheapest FG installed backwards). The exterior siding should not affect the assembly that much at residential fire temperatures (and given the way the tract builders have likely slapped it on, it's drafty and loose anyway).
Galvanized construction has an advantage in having a lot less material to get "involved" in a fire in the first place.
Now, if the FC feels something "ought" to be done, he could suggest moving to 5/8" GWB, which is downright hard to come by not in Type "X" (1 hour rated) form. The local DW people will hate him, but, hey, there it is. If he really wants to be a donkey about it, he can ask the code be changed to 1 hour rated exterior walls (ask your local DW guy how much he like fire pookie . . . <g>)
Now, a "mixed" structure gets more complicated. Like, galvanized walls, but with wood floor trusses, and, say, TJI rafters. "Why" a person would build that way is a bigger question, to my mind, than how to fight a fire in such a building.Occupational hazard of my occupation not being around (sorry Bubba)
DonK,
An average bonfire/ campfire will generate over 1300 degrees of heat
DonK
If the world trade center had been built out of wood instead of steel, chances are it wouldn't have collapsed..
Frenchy wrote:
>> If the world trade center had been built out of wood instead of steel, chances are it wouldn't have collapsed..It would have collapsed from it's own weight before any fire got to it.Ever wonder why you never saw a 100-story timber frame?
Ever wonder why you never saw a 100-story timber frame?
Well, partially due to the fact that there'd only be about 1-200 sf of leaseable space in the bottom third of the floors . . .
Occupational hazard of my occupation not being around (sorry Bubba)
Eric Harper, Well Duh!
Jee I never thought of that! But you see we weren't speaking about strength to weight ratio which your post implies but rather strength of materials in a fire..
The thermal insulational value of large timbers is well documented. several major warehouses here in Minnesapolis have been totally gutted all except for the timbers and exterior bricks. with only minor sandblasting the timbers were reused in the same building doing the same job! try that on a steel framed building!
Frenchy, No duh! Just thought I would point out the maybe-not-too-obvious.
Since were discussing steel beams and heat, I wonder if anyone in here has every straightened out a beam with heat.
We used to straighten them in the steel yard by heating the flange on the obtuse side. We'd heat the flanges cherry red for about 6 to 10 inches, then let it cool. When it cooled, it would contract the beam straight. Don't ask me how....I know it worked because we did it alot on beams that had a kink in it.
blue
Blue-
When I worked for a suspension bridge company, we would bend beams in a similar fashion. Over whatever length you want the bend, heat the side that you want shortened (inside of the curve). Only we never got them past shiny silver heat. I think it was something about strength, the instructions we had were to not get them red hot.
The beams for the Seattle Space Needle were curved that way. They must have gone through a lot of Acetylene.zak
"so it goes"
"As a fireman the standard rule with I joists is to ..."
How do ya know?
not how do ya know the rule ... how do ya know I joist construction vs 2x joists ...
I don't see how this could factor into rushing to put out a house fire.
Not like ya stop by the building dept on the way out and check the prints.
Jeff
Buck Construction
Artistry In Carpentry
Pittsburgh Pa
Flame impingment on the I joist centers causes rapid failure due to the thinness of the wood. Failure of a few joists can overload the entire section causing rapid collapse. No one has figured our how to predict the rapidity of collapse so the general rule is get people and animals out and then fight the fire from the exterior rather then aggressive interior attack. Result is usually more damage before fire is under control. It varies by departments but pull out is faster on joisted buildings then those of solid 2x's. You can talk to your local FD and see what they do. I have been a part-time builder but I have never used anything but full wood or full manufactured beams for support. You have a similiar problem with manufactured roof supports where the metal plates used at joints will heat and curl away causing roof failure. I know it meets code but no one has ever evaluated the Building Code for fire failure that I know of.
My rule of thumb is if the house starts to burn then let it.
Less mess to clean up and better to start fresh. ( However I think the insurance company may disagree)
"You have a similiar problem with manufactured roof supports where the metal plates used at joints will heat and curl away causing roof failure."
That's a popular idea, but it isn't true. Truss plates curl when they're overloaded and pulled out of a joint.
Heat doesn't curl them.
I did a thread a few years back about Trusses and Fires if you're interested in reading it.
Those are my principles. If you don't like them, I have others.
Actually...
We do incident pre-planning for a lot of the buildings in town. Not a big town so it's not hard and has been in progress for many years. If we're on the way to your burning building, we already know a lot of stuff like... do you have sh!tty lightweight roof trusses and a flat roof with A/C equipment on it that it's not designed to support... do you have a large quantity of hazmat stored on the premises... do you have a 500-gallon propane tank right against the back of the building, behind all that cardboard and the stack of pallets... do you have unreinforced masonry... do you have underbuilt stairs... and so on.
We also know stuff like... what's in the building that we should immediately get out if possible? A lot of people have stuff they cannot afford to lose, and we try to know what's where.
Firefighting continues to evolve away from aggressive interior attack (because firefighters get hurt and die doing that) and towards exterior attack and exposure protection. We may enter your building and fight a room-and-contents fire, but we probably will not enter if it's more involved than that. We will prevent the fire from spreading to your neighbor's building. Sorry about that, call your insurance company and get another building.
Not that you really wanted to know.
Not that you really wanted to know.
Yes ... I did what to know. That's why I asked.
I think it's pretty cool than fire depts can and do keep that info handy. In my area ... older/city neighborhood ... it wouldn't work ... as everything's "already been built" ... but I can see how it'd help greatly in areas with a strong mix of the old and the new.
and I can see how having a plan of a whole subdivision could help the fire guys know what they're about to walk into.
Jeff
Buck Construction
Artistry In Carpentry
Pittsburgh Pa
Good answer David: I was wondering the same thing that Jeff brought up.
I'm sure the guys in the bigger cities aren't that knowledgable. Maybe some of the bigger projects might get a warning.
blue
there are places where that sort of information is being compiled into databases, based on permits, inspections, and appraisals. I would even assume that some cities already have it available along with GPS data for the team leader to review on the way to a call. I know our small local FD has been presented with a proposal ...Our FD members are the same tradesmen who build and remodel the hjouses, and who do the caretaking, so there is no need, we know our wayt around..but as I understand it, a team leader could open the screen for the address and have access to floor plan layout and pertinent info relavent to his department such as location of fuel tanks or gas lines. Other city departments would have access to other info relevant to their duties
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
We live in parallel worlds, it seems. The tradesmen here are the firefighters. The clients are generally not. Our emergency medical is also mostly a volunteer service... same folks. As more money moves in and more middle class leaves, the question is, who will handle emergency services?
That question is amplified here. As newmoney moves in the cost of housing is bid up and younger folks move off. The scenario is rtapidly moving to the point that the 'contrator' can live here, but his hired help all commutes. Add to that that the demographisc are aging
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
If I remember, the Isleboro ferry is maybe 10-20 minutes? Easy enough to commute, I guess. Here it's 60-75 minutes depending on route and you need to plan on at least that much waiting in line. A very small number actually commute here daily by ferry. The largest mechanical contractor here has 5-10 men on the island daily and he FLIES them over. Ka-ching. All of the service based businesses, the local government, the trades, the tourist businesses... having problems finding labor because of it.
What becomes a secondary problem then is that fewer young families theen mean there is a break-over point where the school has to close or its operating budget is insufferable. Than means even more folks move off, including essentail professionals like, say, young medical professionals, as well as electricians, heating technicians, plumbers -the kind of people you may have urgeent neeed for in the middle of the night.Our ferry ride is 20 minutes plus loading and waiting in line time, averagea couple hours each way. My main guys get a reservation for one truck. Cheaper fopr me to pay $5 than to pay for waiting time.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Piffen/Dave-
We have the same situation on Long Island, but without the bridge. The folks on the East End, in the Hamptons and that area, need contractors and such. The only way in since it's an island surrounded on three sides by water, is from the west, on a 2 lane highway. It's known to back up regularly for hours. Of course many of the workers cannot even begin to afford rental housing there, far less a purchase. Somehow the prices have gone up more and more.
As far as the firefighters, in general on LI, we have volunteers but I think that's changing. Everyone is working crazy hours to survive, so they don't have the time to do what they need to - drills, training, etc. Couple that with more regulations on the depts, and we have seen some depts that are hiring full time employees, complete with pensions, etc. They get the minimum number so they can roll a truck when they need to instead of waiting for whoever shows up. I can only imagine what the taxes will be when that layer of government has to be paid for too.
Don K.
EJG Homes Renovations - New Construction - Rentals
I have several friends who are firemen in the area. They keep a cheatsheet of how different subdivisions are built.
Of the ten or twelve firemen I know, all swear that they will not enter a house framed with TJI's unless a person is trapped inside.
There is a very prominent Architect in New Jersey who often oversees the building of what he draws. When he does he insists on 2X lumber
So I have been wondering all along...
What percentage of new construction uses I joists?
In our area, I see mostly I joists in the past 6-8 years or so, but I don't have the broadest perspective.
Further...
Is there a total solution (e.g. drywall on basement ceilings, or sprinklers or something else) that would counteract the fire issue?
Other than smoke detectors, egress windows and teaching the kids fire safety, what else can be done to prevent fires/fire injuries etc?
Treat every person you meet like you will know them the rest of your life - you just might!
Brian,You ask, "Other than smoke detectors, egress windows and teaching the kids fire safety, what else can be done to prevent fires/fire injuries etc?"I think a lot of the solution has to be cultural, not legal. Things like promulgating values that favor open space over flammable clutter (think tradional Japanese home), no smoking indoors, a greater care and deliberation in the style of living.Many modern houses are already quite good from a fire safety perspective, thanks in large part to model building codes. The biggest gains now will come by improving the habits of the occupants.Not that buildings cannot improve. They can. Few people will implement the safety improvements until the AHJ forces them to, IMO.Bill
Those are great thoughts Bill - I have built the last few houses for myself - so I have an extreme interest in the fates of the occupants...
I am interested in this thread b/c I used I joists, and while I have no regrets, I realize there are tradeoffs. We build with wood, and wood is flammable to some degree.
I think the nature of the I joist debate is one of degree--taken to the extreme, anything flammable is a problem--we could argue that steel bar joists are a safer solution, or post tensioned concrete...but there might be other problems.
FWIW our floorplan is open - bedrooms off a greatroom, all kids' bedroom windows are ground level, and we don't smoke - but we do burn candles and cook food. So I gave some thought to these issues in the design, but the I joist fire issue wasn't in my mind.
I'm still what the market share is for I-joists
Treat every person you meet like you will know them the rest of your life - you just might!
"What percentage of new construction uses I joists?"
I think it varies a lot from one region to another. Around here I'd guess it's between 80% and 90%.
Q: How do you stop a lawyer from drowning?
A: Shoot him before he hits the water.
Now. amd issue with the I-joists that needs attention (by all of us to some degree) is the "nature" of I joist construction versus "traditional 2x" construction.
On of the big advanatages to a builder/framer in TJI are the very long spans possible, whether as floor, or ceiling, joists, or as roof rafters (one of the few places I see them here in s-o-g country).
Whereas, with 2x, given the state/quality/cost of the lumber, the spans are shorter, or the material is magnitudes of density higher.
So, with the same floor plan, you could, in a fire, have a TJI floor, spanning foundation wall to foundation wall, or a 2x floor with one or two midsapn girts supporting it. Not rocket science to suppose that any failure of a full span floor might (that's an operative word, might) be more dangerous to first responders than one with more supports.
Of course, the question for FRs is what's overhead as much as what's underfoot, come to cases. Doesn't do much good to have a concrete floor if the cathedral ceiling drops in unexpectedly (some very scary early reports in from today's Missouri City fires of alleged problems with some McMansions).
Occupational hazard of my occupation not being around (sorry Bubba)
I'am a G C, teach construction classes at the college and sometimes for the union. My youngest son is now a full time fireman , 9 24 hour shifts days per month. the rest of the time doing construction.. He said that in their fire acadamy class last year they were told of early failure of i joists and engineered lumber.trusses etc. he said some cities have requirements that a sign be posted on the exterior of builds noting their construction type. The city my son works for has onboard computers with all the info they check while on route to a call.
The bottomline is that most people don't care. Not most builders. And most people would never think about it. And if they do think about it, they don't care, save a few bucks.
I don't think there can be any arguement that 1/2 inch OSB will burn faster than 1 1/2 inche lumber. Just can't be argued. So most builders want to ignore the issue and not get into a discussion about it. Adn most people don't even know what an I-joist is.
Next topic?
The recient issue of FH had an article on I-Beams, Jr-Beams & H-Beams with 2x laminated into the webs. I have always felt that a Flitch plate Laminated between 2X's was better partly because the 2x's added fire insulation to the plate. Isn'tl it is the verticle depth of the steel that is the source of the strength. My prefered floor layout has always been a Flitch beam imbeded in the joist line reather than beams and posts underneath. HVAC & Plumers dont like them though.
Any Comments?