Thanks for a great discussion. While having experienced the fire racing up the outside of the building I guess I hadn't made the connection between that and lightweight construction.
Here's one for you. Many years ago on a POC FD that I used to belong to we had a fire in a 8 unit apartment building. We thought the fire was in the first story apartment to the left of the entry way. A crew went in and searched the apartment with a hose line, cetain they would find the fire. They found nothing but light smoke conditions and very little heat. They came out and another crew headed in, same thing. Just as the third crew was about to enter and another crew was heading down to the basement the entire living room floor of the apartment fell into the basement.
The fire had started in the basement below this apatment and and burned through several of the floor joists, and most of the the plywood floor decking. What we didn't know is they had poured about 1 inch of lightweight concrete on top of the floor decking for sound deadening. That is all that held the floor in place until just enough of the support underneath it burned away and collapsed.
No warning, no sag, nothing just boom and gone.
what i have found for the most part the 1st company (5 man crew) can place one guy on the exterior line (short duration likely), and then simultaniously get a crew and hose to front door of a residence in those type of exterior fires.
i have had done that twice two years ago. we have had a rash of wood framed chinmey fires a while back and got a few communicating into the attic. besides ensureing it wasn't on the lower floors we pretty much had an isolated attic fire then.
Pertaining to truss roofs however, I do not understand why so many people freak out and are so scared of ALL of them. Sudden, early, and total collapse of truss roofs occurs in buildings with large, unsupported spans - like churches or warehouses. Truss roofs in lightweight residential construction does not fit in this category. These roofs burn away, they do not fall down in mass. Small structural boards that may fall, fall to the ceiling joists. Even most McMansions have typical size rooms. There are not large open spans, just more rooms.
And for all the naysayers that will chime in behind this post, I once again off a challenge:
Find one documented incident in the history of the fire service where a firefighter was killed or seriously injured as a result of a truss roof failure in a residential building.
If I remember (yeah, right...) I'll take some pics of the truss signs when I go back to work on Jan 3.
Once again you have got to know you enemy 'the building".
A lot of new construction I see now is the glued together trusses like you mentioned with only 1/2" press board (chip board) as the roof sheeting and shingles upon that. Once that gets hot, the glue gives way so we constantly watch the roof and avoid going up if at all possible. Same for the flooring...if we can get a good quick knockdown great, if not, then we pull out and surround and drown.
Good topic by the way, just saw it.
I work for a pretty aggressive Dept when it comes to fire. 90% of the time the initial attack crew (Normally the first due engine Co) will have a truck crew RIGHT behind them and there job in this situation will be to expose this fire in the walls, attic, etc.. but we are pretty lucky to have a lot of man power on a working job. Within 3-4 minutes you will have 3 engines (with 3-4 each), 1 truck (3-5), and a rescue (2-3) ready to work... A lot of the time the rescue (ambulance) will be assigned to primary search while the truck company is assisting the engine crew with fire attack or venting ops. So command will go ahead and start another rescue for medical sector.. I've seen PLENTY of house fire stopped and property saved when its gone beyond a room and contents.. But there is a point to were you just write it off and go defensive.. But I've gone in and stopped a fire that most would right off..
Can anyone give their feeling on the lightweight fires they have been to? We have been told over and over about the lightweight trusses collapsing and that reinforcement has saved lives, but with our smaller SFD's that are compartmentalized, thus the partitions may be supporting the trusses more, it seems that our department has been noting that instead of trusses and roofing collapsing, it seems more apt to just burning away.....I'm not advocating staying in their, just wondering if other places are noticing that too.