This column supplements the article “The Hazard of Suspended Ceilings” by Stuart Grant and Les Stephens published in the January 2005 issue of Fire Engineering in two aspects.1

The suspended ceiling may be a part of a fire resistance-rated floor and ceiling assembly providing membrane fire resis-tance as contrasted with directly applied “fireproofing.” Removing a single ceiling tile from such assemblies subjects the steel bar joists to the full effect of the fire.2

Similar assemblies are used in buildings not required to be fire resistive. In such cases, the ceiling tiles need meet only flame spread requirements if a ceiling is desired. This provides no rated fire resis-tance. There is no way to tell the assemblies apart. In the trade, persons who do not understand the difference between fire endurance and flame spread often use the term “fire rated” indiscriminately.

Building information should include the code class of the building. If it is classified as fire resistive, note whether the rated fire resistance is achieved by a vulnerable floor and ceiling assembly and whether columns are unprotected where they pass through the plenum space (this hazard is discussed later in this article).

It is a common practice to remove tiles from nonpublic areas such as storerooms (often a high fire load) to replace damaged tiles. The building management should be notified in writing of the necessity for maintaining the integrity of the ceiling and to have a stock of the original tiles on hand for replacement. Any missing tile should be cause for a citation, and notification of the collapse hazard should be incorporated in the dispatch information.

I am often asked how could this be permitted. The following material is abstracted from a paper entitled “How did we get into this mess?”3


In the 1960s, the steel industry was faced with competition from concrete as a high-rise structural material that could brag that no expensive ‘fireproofing’ such as that required for steel was needed since concrete acquires rated fire resistance by the way in which (hopefully) it is manufactured.

The steel industry, which had formerly bragged about how many tons of steel went into a high-rise building (the heavier the concrete ‘fireproofing,’ the more steel was required), worked hard to develop lighter cheaper methods of passing the ASTM E 119 Fire Resistance Test and thus get rid of the heavy concrete that has served well.

The principal product offered was a steel bar-joist floor with ‘left in place’ corrugated steel forms, which provide the tensile strength (otherwise supplied by reinforcing rods) required for ‘reinforced’ concrete, and protected by suspended ceilings of tiles on a steel grid. The tiles would also meet flame-spread requirements, and the void is useful for concealing wiring, ductwork, and even as one side of the HVAC system.

In the first edition of Building Construction for the Fire Service (1971), I pointed out the basic deficiency of this system-the loss or failure of one tile exposes the entire floor to the fury of the fire below. A steel industry representative denigrated the book as a “good book for people who can’t read.” When I challenged the individual at a meeting, he said, “It’s a good book.” I was told by a U.S. General Services Administration (GSA) fire protection engineer that the GSA never built a building for its own account with this type of construction.

When inspecting, do not skip a locked storeroom. I have found these locations have high fire loads and missing tiles that were removed to replace damaged tiles in more visible areas.

The steel industry also promoted the idea that columns need not be protected where they pass through the plenum area (the ceiling void) because the “ceiling would provide protection.” The absence of a tile might lead to a massive collapse because of column failure.4

I worked in a building where this had been done. I was told by the Montgomery County (MD) Building Department that the BOCA National Building Code approved this practice. Some years later, I was doing a series on codes for the International Association of Fire Chiefs. I mentioned this item. BOCA said it never approved such a construction.

I was given a National Gypsum report on a test that showed that this concept worked. A Factory Mutual representative at the test had written “top floor or one-story building only.”5

One of the serious problems of our fire ratings under ASTM E 119 is the fact that no notice is taken of real-life circumstances-for instance, wooden floor and ceiling assemblies are rated on a test fire that assaults the structure only from below; today’s plastics can and do produce fire puddles on the wooden floor.6 The bar joist and suspended ceiling is totally vulnerable to the removal of a single tile for whatever reason. Spray “fireproofing,” never tested, can drop off, as happened in the 9/11 World Trade Center collapses. The ceiling itself is a severe hazard to firefighters.

I wrote the following in my Ol’ Professor column in May 2001:


One of the weapons of the Roman gladiator was a net and a trident (a three-pronged spear). The opponent was entangled in the net and stabbed to death. Many ceilings consist of tiles that meet the ASTME 84 flame spread standard, not fire resistance. Note that the undefined term ‘fire-rated’ is used indiscriminately (see BCFS3, 294-296). These ceilings are supported by a lightweight steel grid that is suspended by wires. At the McDonald’s fire, one Houston firefighter, who escaped, and one victim were entangled in the wires. The breathing apparatus tank is particularly vulnerable to entanglement.

A Memphis, Tennessee, firefighter died in a high-rise fire when he became entangled in wires that were above the ceiling in the hallway. FDNY firefighters have reported becoming entangled in cable TV and other wiring that was just glued in place; the adhesive melted.

There is no ready solution for this problem. Some agencies with adequate resources should work on it. Where possible, avoid open areas, and stay as close as possible to walls or half-high partitions, which may keep the ceiling from coming all the way down. Surprise may cause panic-driven efforts that are ineffective and waste air. Firefighters should be trained about this hazard and call a ‘Mayday’ as soon as they become entrapped. Wire cutters were found near one victim. These cutters could be used to cut wires but would be ineffective on the metal grid units. Rapid intervention teams should be aware of this hazard and be equipped with a tool that can cut the metal grid units rapidly.


The other serious concern with suspended ceilings is they are used to conceal old combustible acoustical tile in building renovations. Apparently, no code forbids this deadly practice. The fire service has been slow to appreciate the hazards.7

I wrote the following on this hazard in the column cited above:


The suspended tile ceiling is another hidden hazard. It is often used to rehabilitate older buildings that have combustible acoustical tile installed. The tile may be glued or on a wooden structure.

A most serious related hazard is often created when a building is remodeled. The code requires that a new ceiling that meets flame-spread requirements be installed. No code of which I am aware requires that the old ceiling be removed.8

The new ‘fire-rated’ ceiling is installed below the old ceiling above. Fire will burst down out of the void. Two firefighters died in Wyoming, Michigan, when fire burst out of the ceiling. Even then, the city did not amend the code.

Sixteen persons died in the fire at the John Sevier Nursing Home in Johnson City, Tennessee. The fire involved combustible tile left in place when a new grid ceiling was suspended below.

The National Institute of Standards and Technology estimated that the CO production in the void could be as much as 50 times greater than without the void. NIOSH Report 98F-06 describes a basement fire in which an inferno burst out of the ceiling when the new tile ceiling was opened. Two firefighters died.

When inspecting a rehabilitated building that shows a new suspended ceiling, pop a tile and see if old combustible tile is above. In a fire, I would use a big line with an open bore tip to tear down the ceiling and eliminate the void.

If the department becomes aware of a rehabilitation project, let the owner know how hazardous it is to hide the old tile. Recommend that it be removed, to avoid the creation of a bomb. If the owner refuses to remove the tile because ‘the Building Department said it was OK,’ describe how operating a big line that throws one ton of water a minute to blow down the ceiling will eliminate the bomb. (excerpted from The Ol’ Professor, September 2000.)


1. This article is available at

2. Building Construction for the Fire Service, Third Edition (BCFS3), 292-298.

3. Available on request from

4. Sketches of this are on page 195 of BCFS3.

5. BCFS3, 291-298.

6. Wood trusses provide a void through which fire has entered laterally. This is not evaluated in the test.

7. For a comprehensive discussion of this hazard, see BCFS3, 387-392. A photo of a backdraft fueled by combustible tile can be seen on page 423 of BCFS3.

8. I have been told that the old Standard Building Code can be read to prohibit this practice. It should be forbidden in so many words.


A previous Ol’ Professor (December 2004) recommended that units searching upper floors for victims carry a CO detector, since CO is carried up by stack effect. Deputy Assistant Chief John Norman, Fire Department of New York’s chief of special operations and author of Fire Officer’s Handbook of Tactics, Second Edition (Fire Engineering, 1998), has informed me that all FDNY rescue, squad, and ladder companies (which routinely conduct primary and secondary searches for victims) carry CO detectors attached to the officer’s radio strap.

I repeat my recommendation that a thermal imaging camera (TIC), the firefighter’s radar, be used to examine all void spaces for hidden fire, particularly overhead

The Granbury (TX) Fire Department reported using the TIC to detect fire in the truss roof of a commercial one-story building, going defensive, and thus escaping the roof collapse. If you have a similar story, please send it to me at

• • •

On a cold day recently, FDNY firefighters had an electrical fire in the basement of a 16-story structure. A “progress report” noted high CO readings on the upper floors.

FRANCIS L. BRANNIGAN, SFPE (Fellow), the recipient of Fire Engineering’s first Lifetime Achievement Award, has devoted more than half of his 63-year career to the safety of firefighters in building fires. He is well known as the author of Building Construction for the Fire Service, Third Edition (National Fire Protection Association, 1992) and for his lectures and videotapes. Brannigan is an editorial advisory board member of Fire Engineering.

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