TJI Type Joists + Fire 1

[CANPRO]

I've heard people talk about how these types of wooden joists, the ones with a plywood/OSB web, don't hold up well in a fire.

I'm just about to do some searching on the internet...but I was wondering if any of you have had any direct experience with how well these types of joists resist fire.

 

[dik]

I've been involved with several fire investigations and they don't do well... in addition, they can be dangerous to firefighters due to loss of load capacity... they also burn fast... when 3/8 particleboard/plywood chars, there's not much load capacity left.

Dik

 

[msquared48]

ESR 1153, pages 18 to 20, has several fire rated assemblies shown, some with insulation.

The implication to me is that even with "fire resistant" glue, elevated temperatures will lower the joist capacity before the fire reaches the joist through the assembly. That's the problem.

I agree with dik here. You might try calling Truss Joist, or similar manufacturers and see if you can get an applied load performance curve relating to temperature. Don't know that they will accommodate you, but it can't hurt to ask.

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[Forensic74]

Around me there are several jurisdictions that dont allow them because of the fire cheif's experience with them in fires.

 

[dik]

MM10 is on the mark... you may want to talk to several firechiefs (chieves?) about heir experience with them and what they can recommend... might give you a better answer than TJI rep...

Dik

 

[CANPRO]

Thanks for the responses...Someone once told me that firefighters won't enter a burning house if they know there are TJI joists, which is why I posted the question in the first place.

It makes sense just thinking about it that they wouldn't last long in a fire...but its always nice to hear some 1st hand experiences.

It would be interesting to hear the opinions of the firefighters vs. TJI rep

I just find it odd that there are obviously safety issues with this floor system, but I see homes being built with them all the time with no added fire protection...seems like the building codes should have addressed this already

 

[dhengr]

Actually, I believe the building code which was in competition with the ICC/IBC in the early days of that national adoption fight, the one proposed and pushed by the firefighters (NFPA 5000, I think), did take exception to these products for all the reasons mentioned above. The NFPA (National Fire Protection Assoc.) might be the place to go for their side of the story.

 

[SkiisAndBikes]

No direct experience, however I have a friend who is a fire fighter and we have had several discussions about all the 'new and innovative' structural framing sytems now being supported in the local building codes. The summary of his opinion is essentially that they 'don't build them like they used to' and the fire fighters in the local hall are wary of any newer type constructions.

He felt the local fire fighter training college would benefit from a module taught by a structural engineer to provide an overview of the common structural framing type systems in use and their relative performance under fire situations.

 

[BAretired]

TJI joists have virtually no fire resistance on their own. They rely completely on the protection provided by ceilings, usually gypsum board. When the ceiling goes, the floor goes...end of story.

BA

 

[MiketheEngineer]

We had this problem when roof trusses became common. Firefighters were scared - and maybe rightly so.

I have even heard of jurisdictions that make the homeowner post on a front window that the house has wood beam floors and/or roof trusses. Theoretically this informs the fire fighter of any possible problems.

From my experience, most fire fighters do not enter a residence unless they feel there are people involved. They just stand back and hose it down until they can safely walk in. Makes sense to me.

 

[Splitrings]

I have been a volunteer firefighter for about 20 years and also have an engineering background. Nothing holds up to fire better than solid wood members, especially large ones. Most firefighters today are well aware of the dangers of roof trusses. I have had the chance to be on the roof of a manufactured home with trusses made of 2"x2" members. I am all for conserving our resources but this is a little ridiculus. Now the use of wood I joists and floor trusses are becoming almost the norm now. I have no personal experience with them but have seen plenty of case studies and the results are not good. These floors are giving out much earlier in the event of a fire. A comment was made about firefighters only entering a structure if they suspect people are inside. This isn't the case. We are a small rural fire department and have been doing aggressive interior firefighting for 15 years. Our state requires all commercial buildings be placarded with a red triangle with the letters F, R or FR. This indicates Floor and or Roof trusses.

 

[MiketheEngineer]

Give me a 6x12 wood timber any day - even over an I-beam in a hot fire. You will live a lot longer!!

I am not a firefighter and I admire that they put their life on the line everyday!!! But the economics say that we use the minimal resources when building. Sure we could build a house that was virtually fireproof - all concrete or fully sprinklered. Like that is going to happen!!!

Our local county tried to get sprinklers in all new houses. That quickly went down the tubes.

And actually how many newer homes burn?? With modern electric services, smoke alarms, etc - not too often where I live - except for the village idiot that fries a turkey in/on his garage/deck or dumps hot fireplace ashes in his garbage. Both happened recently. Admittedly, lightning has gotten a few - but not very often.

IMHO - I would just break out windows and stick the hose in - save myself and maybe/maybe not the building - but its not my building so I don't really care - as long as no one is in there. Take it up with insurance company.

 

[CANPRO]

Splitrings...I like the idea of posting the red triangles. I sent an email to the local fire dept. the other day asking their general opinion on this floor system, but I haven't heard back from them. It seems like giving firefighters a heads up on the framing is the least you could do.

Mike...I didn't look for the exact reference for fire rated assemblies that you mentioned, but I did find a few.

http://www.woodbywy.com/literature/1500.pdf

The most of I've ever seen added to the joists is a single layer of gypsum...clearly this is the absolute minimum, but I've seen many unfinished basements with exposed joists. Maybe the building inspectors need to be educated a bit more on the matter.

 

[MiketheEngineer]

5/8'' type "X" fire rated sheet rock will give you about an hour's worth of protection. Should be mandated in all residences. It is for the wall/ceilings between the garage and living spaces!!