HIDDEN FIRE AND COLLAPSE
by Francis L. Brannigan, SFPE
In my last column (August 1995), I discussed the deaths of four firefighters who possibly may have been saved if there had been proper preplanning. In the Seattle tragedy,1 summarized below, it is most likely that preplanning at the level carried out by most fire departments would not have uncovered the alteration in the structure responsible for four fatalities when the floor on which they had been working collapsed into the basement raging with fire. Additions had been made to the 95-year-old Mary Pang Food Products warehouse building, which also was buried in the earth 70 years ago, when the street level was raised. The former one-story building became the basement of a two-story building. The existence of the basement was unknown. This led to confusion on the fireground with regard to the locations of units. A firefighter felt the concrete topping over the wood floor and found it to be hot. Assuming that it was the basement floor, he decided to ask the lieutenant about it after the fire.
The building had not been preplanned. All major older buildings should be preplanned; incredible alterations probably have occurred over the years. In this case, an additional floor was added. One brick wall was too low. A “pony wall” of 2 ¥ 4 wood studs was erected atop the brick wall to support the new floor joists (see illustration on page 91). The roof was supported on a column or columns standing on the new floor. The interior finish did not make the serious inconsistency in the structure apparent during a casual inspection.
After the collapse, I was asked at several seminars, “How could it happen? I heard it was a heavy timber building.”
SOME COMMON MISCONCEPTIONS
Firefighters are taught that buildings are divided into five classes, one of which is heavy timber. Unfortunately, this simple broad-brush breakdown appears to be a good example of Alexander Pope`s “A little learning is a dangerous thing.” The danger is in the details.
A serious fallacy is all too commonly believed: “All heavy timber buildings have excellent fire resistance.” Although appropriately built mill-construction (heavy timber) buildings may have significant inherent fire resistance, no heavy timber structural element was ever able to get even a one-hour fire resistance rating under ASTM E119.
“Heavy timber” as designated by building codes often falls far short of the inherent fire resistance of true mill construction as originally conceived for the New England textile mills, in which each known weakness was engineered out of the structure.2 Sentences that read, “Heavy timber, or as it is sometimes called, `mill construction`…” are dangerously incorrect.
Remodeling often degrades the inherent fire resistance in all types of wooden buildings:
A common structural deficiency occurs when a stairway or other opening is relocated. The patch of the old opening is usually supported on 2 ¥ 4s, not heavy timber.
Unprotected steel is used to replace a defective heavy timber column.3
A rebuilt roof can present a “death trap,” as is the case in Boston (see photo right). Part of the roof of this “historic old dump” is sawn wood beams. The rest consists of wooden I-beams. One end of the I-beam rests on a plank shelf supported by steel brackets lag-screwed into the block wall. After the ceiling is in place, this condition would be another deadly secret. I know of this hazard only because I looked at it with Captain Dave Mager when the building was under reconstruction.
New gypsum board ceilings dropped well below the old high ceilings create a huge void in which explosive CO can accumulate and fire can extend unchecked. Do not believe that this construction feature provides the equivalent of “rated fire resistance,” even if the building department says so. The ASTM E119 test, which rates fire resistance, permits only severely limited void spaces.4
These are just a few examples. Remodeling operations on older buildings should be studied carefully and frequently for death-trap installations. Don`t believe that “All is according to code” is any guarantee of firefighter safety. (If you see an example of unique remodeling, shoot a slide, send it to me for possible use, with credit, in the Preplanning Building Hazards column.)
Other examples of hazards within structures appeared in the following particularly excellent articles in recent issues of Fire Engineering:
“Removing Security Bars,” Captain Bill Gustin [Metro-Dade County (FL) Fire Department], July 1995. Note particularly the caution on using PPV and fog, which may make firefighters more comfortable at the cost of injury or death to occupants.
“Rapid Intervention Companies,” Captain Jim Cline [City of New York (NY) Fire Department], June 1995. I have seen utter chaos on the fireground when a firefighter was reported missing or in trouble. There can be no doubt that some firefighters who have died could have been saved if the fire department had planned, trained, and been equipped to react promptly to a firefighter in trouble. [A fatal light wood truss collapse in Louisville, Kentucky, (to be discussed in a future column) led the Louisville Fire Department to develop a formal policy on rapid intervention groups.] Note also the excellent discussion of how firefighters get into trouble.
“Risk Taking on the Fireground,” Battalion Chief Frank C. Montagna (FDNY), August 1995. This experienced fireground commander makes many excellent points, some of which should be framed and posted. Examples include the following: (1) “Save life first, then save property–never forgetting that the firefighter`s life is included in the life portion of your mission.” and (2) “A prime responsibility of each firefighter and officer is to return to his family at the end of the day.”
When I was teaching at Montgomery College, I went to every serious fire in the area. Sometimes the IC would ask me, “Should I pull them out?” The Irish are known for answering a question with a question, such as, “What are they accomplishing in there?” This put the IC in the position of making the risk-benefit analysis. The usual result was to go defensive; the risk wasn`t worth the results. Think of the “great stops” you made that were bulldozed the next day.
“Shifting Gears to Defensive Mode,” Battalion Chief Donald W. Stukey [Los Angeles City (CA) Fire Department], August 1995. It includes a review of many valuable pointers for getting out of dangerous buildings. Note also the photograph at the lower left of page 52. These Los Angeles firefighters withdrew from a building when a roof collapse was correctly anticipated. They did not withdraw far enough, however. If you must withdraw from such a building, do not take positions at openings or in the collapse zone. The roof collapse may send a blast of fire out of all openings and bring down the wall(s).
Note: Failure to shift to a defensive mode in time seems to occur at times to firefighters who do not experience many serious fires. In one such instance, a fire in an 880-square-foot residential basement was delivering very heavy smoke. Firefighters were attempting to get down the basement stairs. They noticed that the floor was soft. They started to get out. A firefighter lost his life and another barely was dragged to safety when the floor collapsed.
If we take the time of the alarm as 0000, the arrival time was 0011. The second hose team (the victims) was entering the building at 0025. The collapse occurred at 0029.
When the National Bureau of Standards (now NIST) made the comparative ASTM E119 tests between steel bar joists and nominal two-inch sawn wood beams many years ago, the steel bar joists lasted only seven minutes; wood joists lasted only 10 minutes. The test structure has a double wood floor, not the currently common single sheet of plywood. This test involves a static floor load of 30/40 pounds per square foot (psf). This cannot be compared with the dynamic floor load of about 675 pounds of three fully equipped firefighters. More recent tests have shown basement fires to reach 1,500°F in five minutes–the test fire is only at 1,000°F and climbing at five minutes. The test time always begins with ignition. The time element between ignition and alarm is rarely known and can be considerable.
Some time back, a fire department responded to a basement fire in an apartment house. A “heavy” electrical service in the area was sparking and spitting. Operations were suspended for 45 minutes until the power was cut off. Firefighters then charged into the building as if nothing was different. Three fell into the basement and were badly burned.
In short, ordinary wood joists that have been exposed to substantial fire for several minutes may have very little resistance to collapse under the dynamic load of several firefighters. If you are not winning, you are losing. The building`s gravity resistance system is under attack, and the building is deteriorating by the minute.
I urge all fire departments to adopt the following standard terminology: Dispatch to a “building” fire. When the fire is beyond a simple contents fire and is affecting the stability of the structure (wood burns, steel and concrete fail), then the announcement should be made: “This is a structural fire”–putting all on notice that the gravity resistance system is under attack. Operations must be adjusted accordingly.
I repeat that I believe we mislead firefighters in fire training buildings. The emphasis is on taking the punishment and putting the “wet stuff” on the “red stuff.” There is no concern for hidden fire or collapse; these elements are too dangerous to be permitted in training. These hazards must be taught in the classroom–as effectively as live firefighting. Reread my column in the August 1995 issue and note the similarity of the above incident to the Pittston fire, which claimed two firefighters` lives. n
1. “Four Firefighters Die in Seattle (WA) Warehouse Fire,” U.S. Fire Administration Report #77, prepared by Gordon Routley of TriData Corporation. The complete report is available without charge from the U.S. Fire Administration, 16825 S. Seton Ave., Emmitsburg, MD 21727. Send for it and study it. Ask yourself, “Can this tragedy be avoided?”
2. Compare a “heavy timber” building in your jurisdiction with the description of true mill construction on page 204 of Building Construction for the Fire Service, Third Edition.
3. A photograph of this kind of hazard was published in my article, “Preplanning Building Hazards,” Fire Engineering, March 1995, page 103.
4. Building Construction for the Fire Service, pages 186-189.
FRANCIS L. BRANNIGAN, SFPE, a 52-year veteran of the fire service, began his fire service career as a naval firefighting officer in World War II. He?s best known for his seminars and writing on firefighter safety and for his book Building Construction for the Fire Service, Third Edition, published by the National Fire Protection Association. Brannigan is an editorial advisory board member of Fire Engineering.