In a recent article in the fire service press, Kirk Grundahl, an apologist for the truss industry, said in a paraphrased quote that the firefighters have emotion on their side but the truss industry has the facts.
About 11 years ago I was invited by Joe Piscione PE, an official of Truss Joist McMillan, to address a meeting of truss people in Salt Lake City. Among the pictures I showed was a slide of an attractive three story wooden office building. Then I "undressed" the building, a mass of trusses. I explained that in a fire, firefighters would get on top of this burning pile of kindling to cut a hole in the roof to let the smoke out so other firefighters could get into the building. Collectively the audience gasped.
Shortly thereafter the USDA Forest Products Laboratory started work on finding ways to make trusses safer. The report noted that the work was in response to concerns raised by this writer. The final result is that to make a truss capable of achieving a one-hour rating under the weak ASTM E 119 test, the truss would have to be entirely sheathed in gypsum board. (I saw such trusses n Alexandria, VA a year ago but the pictures are lost.)
NEVER FORGET THAT A ONE-HOUR RATING DOES NOT MEAN ONE HOUR IN A REAL FIRE. See Chapter 6 of BCFS3 to understand.
The report suggested that since trusses collapse suddenly while sawn joists sag, it might be possible to design trusses with one part weaker so that the truss would sag before failure thus warning firefighters? Neat idea. My dream of dreams is to have some truss enthusiasts on a line in thick smoke with a firefighter's radar showing fire in the truss floor below.
Mr. Joe Piscione, an official of Truss Joist McMillan, spent his company's money to attend the IAFC meeting in Anaheim in 1992 and the additional fee for my pre-conference seminar on Trusses.
His letter appears below. I suggest you save this for the time when you are presented with arguments like Grundahl's. Note that Mr. Piscione bought a copy of Building Construction For The Fire Service, Third Edition. I never received any correspondence from him or anyone else in his company arguing that anything in the book was incorrect.
TRUSS JOIST MacMILLAN: A Limited Partnership
September 16, 1992
Mr. Frank Brannigan
Port Republic, Maryland 20676
Dear Mr. Brannigan:
I appreciated the opportunity to attend your presentation in Anaheim. It gives me a better understanding of the fireman's perspective when preparing to fight fires in various building types.
As a whole, I believe your comments on wood trusses, wood I-joists and connection were fairly stated.
If your objective was to provide a better basis for tactical considerations for fighting fires under various structural conditions, then I believe you were successful. Particularly, I think your advice about pulling out of building when the structure becomes involved in fire is sound advice. Fire fighters need this kind of direction from a recognized authority.
One thing I wanted to do was to order a copy of your new edition of "Building Construction For The Fire Service", so enclosed is a check for $45.00.
If I can ever be of assistance, please don't hesitate to give me a call.
Joseph R. Piscione, P.E.
Manager of Product Acceptance
THE FIREFIGHTER'S RADAR
Get the firefighter's radar (the thermal imaging camera) in the hands of a trained operator and up to the nozzle. Seek out fire in the ceiling, in the floor and in the walls. In recent months there have been several cases of firefighters falling through floors. The radar would show fire below.
Floors aren't what they used to be. They used to have a pine sub floor and a hardwood walking surface. Now it is a piece of plywood (which delaminates) covered with carpet, which may not meet modern flammability standards.