Ch. 12 Ceiling collapse Flashcards
Ceilings are non load bearing structural elements that support only their own weight. Their collapse does not cause the collapse of other structural parts. What is the danger of a ceiling collapse during a fire operation?
The ceilings can drop over FF’s and trap them inside burning bldg.’s
There are 2 types of ceilings those that are directly affixed to the floor or roof joists above and those that are suspended several inches or feet below the joists by vertical strips of wood, steel hangers, or thin wires. The most dangerous ceiling is which one?
The suspended ceiling
Older bldg.’s have lath and plaster ceilings while newer bldg.’s use dry gypsum board that are 4’X8’ in area and 1/4”-3/8” thick. At fires a directly affixed ceiling usually collapses in small pieces. When the plaster is only how many inches thick will a FF with a properly fitted helmet suffer no serious injury?
1-2 inches thick
In a older structure where plaster ceilings are 15-20 feet in height and how many inches thick will a FF suffer unconsciousness or a serious head or neck injury when a large area of thick heavy plaster collapses?
3-4 inches thick
Suspended ceilings are most often found in 3 types of occupancies: stores, top floors of MD’s, and renovated bldg.’s. These ceilings are sometimes called dropped ceilings or hanging ceilings and are constructed several inches or feet below the supporting roof or floor joists. What are their uses in each of the 3 occupancies?
( 3 separate answers for each occupancy)
Stores- these ceilings are used to cover older ceilings which are out of fashion and found above.
Top floor of MD’s-creates a space to insulate the top floor from the suns rays.
Renovated bldg.’s- its found on every floor of every apartment and is used to reduce the floor height to conserve the energy for heating & cooling the apartment.
The 3 most common types of suspended ceilings are the wood grid system with a permanently affixed ceiling, metal grid system with a permanently affixed ceiling, and the lightweight metal grid with a removable panel ceiling. The ceiling collapse killing most NYC FF’s is the?
Wood grid system.
Although considered lightweight, a lightweight metal grid system with removable panel still presents FF’s with what type of hazard?
An entanglement hazard
Immediately after a wood grid suspended ceiling collapses, there is sometimes a rapid increase of fire in the space directly over the fallen ceiling. the following occurs: The air space BELOW the ceiling is momentarily compressed. The air space ABOVE the fallen ceiling is momentarily placed under vacuum. The wood grid fuels the fire at the floor level while the joist fuel the fire above.
What should be done 1st to protect any FF’s that are trapped?
What should be done 2nd?
The 1st step to rescue trapped members is to sweep the collapse area ABOVE the ceiling collapse with a hose line and knock down the flames.
The 2nd step will be to use a portable ladder and attempt to hinge the collapsed portion of the trapped member/s freeing them.
When multiple suspended ceilings are encountered who MUST be notified?
The Incident Commander
A fire inside the lowest ceiling of a multiple suspended ceiling will usually be contained and generally will not extend into the 2nd and even 3rd suspended ceilings.
True or false
False
It will usually not be contained and will spread to the other dropped ceilings.
During a ceiling collapse rescue attempt should be made from adjoining stores because the partition walls can be penetrated faster than the rear masonry wall. Why is this statement true?
Windows and doors at the rear of the store are usually bricked up or securely locked. When using the adjoining stores hose lines should be positioned to prevent fire spread
The IC should limit the number of members participating in the rescue attempt for what reason?
The combined weight of the rescuers can be greater than the weight of the fallen ceiling and could crush the members trapped below.
How can we use an exterior cellar entrance to gain entry to the store?
Sometimes these outside cellar entrances will lead to an interior cellar entrance which may allow access to the store.
