I just sat in a seminar class about light weight construction. The class was excellent and I will tell you this, we need to rethink how we are going to fight residential structure fires. The way the new truss-style construction is made, it is not safe to go on a roof or into the building any more.
It’s been demonstrated that the new construction material is burning through at a much faster rate and so by the time we get to the scene there is a danger of collapse, if it hasn’t happened already. Also, in many cases, due to this faster fire development, the buildings are more heavily involved in fire when we arrive on scene than with more conventional construction.
This bothers me, because we still fight these fires like we would with the older homes. There is a huge difference in the amount of time that we have to do a search; the ten minutes we used to spend on an interior search in older homes is not feasible in the new buildings. We really need to start thinking more when we get on the scene of a structure fire about whether we really need to be on the roof and whether we really need to go into the structure.
Ok, what do you all think, am I overreacting to what I learned in class? I don’t think so.
Actually, this is nothing new to the fire service. They have been building buildings with truss construction for over 30 years. Back in the 1980's LAFD did a study on the different type's of construction they had been responding to. Very informative the findings. i think we as a fire service hear the term "truss" or " light weight construction" and we all get a little ahead of ourselves. Most of the fires we encounter do not even affect the structure of the building, and too often i hear firefighters panic over these buildings. Do you have to change the way we go in these buildings? Yes we do, so dont jump on me there, but we still have to contain the fire perform search when needed and if we can contain the fire quickly. In the smaller depts with little manpower, and a far longer response times your approach will be different then mine.
We have started a campaign to mark those houses in our district constructed with lightweight materials. Also, the county now benchmarks structure fire incidents with announcements over the radio every 15 minutes, to let the IC know how much time has elapsed since the alarm.
Yes Joe, I do think there is a little over reacting with these buildings. Are they dangerous, sure they are. I didnt say they are not. Do i think we should just stop and break everywindow and play handlines into the one room fire in a single story building...Not at all. These buildings are not new but people are just starting to talk about them. Where have you all been?
For simple room and contents fires I have read how alot of depts really do over react.
One of the changes in truss manufacture that I have seen for the US (not here yet, thankfully) is the replacement of the gang-nail connectors and gussets with finger and groove glued joints. The glue vapourises pretty quickly. No glue means a couple of bits of timber that have received a divirce, they part quickly. These are being used there for both roof and floor trusses. I don't know how widespread the practise is, but it is happening.
But I agree with you, it doesn't mean every fire becomes a surround and drown. Here we still arrive in time in most cases to attack and contain a room fire. Probably most of you do as well. Perhaps the change that's needed is too be more aware of the chance of a quicker spread of the fire, and the resultant loss of structural integrity. It's always happened, it's just that with the newer construction methods it's likely to happen sooner. Much sooner.
The problem is that the plates being used to hold everything together is not the same from years ago. They are flimsier and cheaper material. The trusses themselves aren't being made in the same way either. Everything is being made lighter and with cheaper material. Floor joists are not one piece of wood any more they are a 2X4 at the top and bottom and a piece in the middle that is a plywood type material. I don't know about you but I sure wouldn't want to stand on any of those in a fire situation. If you ever see this class offered I recommend taking it. There is so much more that I just can't put here. Very good class.
I agree we need to rethink our tactics as well as It would be nice to have the areas we cover to make it manditory that we be able to set up some pre-plans with the residents at these houses to make sure what kind of construction we are dealing with. In our area we have older homes as well as newer ones but also some that have been remodeled.
John, a pre-plan for every house in your area? Or just for those that are identified as being of the modern, cheap, light-weight construction?
Ed, you say you haven't seen a collapse yet on a savable house. Isn't that just the point? We can still be called upon to go internal on a house that may be only marginally savable, that's where modern trusses could be putting us in more danger, and yet not be visible.
A system not mentioned yet in this thread is the joist with timber upper and lower stringers, joined by flattened sheet steel V's. The last house fire I attended had this type of joist as floor/ceiling. Those over the kitchen (area of origin) still had the stringers, but all the steel parts had fallen away and were on the kitchen floor. The timbers had a distinct downward bow - the upper story was not at all safe. The house looked to be somewhat repairable until you saw those joists.
Being new to fire fighting but not to common sense, is there a connection to approving home construction types to how quickly they burn? Are home builders and government inspection agencies on the same page as us in this matter? Are fire departments expected to change their tactics because of greed in making home cheaper to build? Hope to find the real answer here. TCSS