Flashcards in Dunn Chapters 5,6,7,8 Deck (48):
A masonry parapet wall is one of the most dangerous walls that a firefighter can encounter at a fire. The most dangerous AREA outside of a burning structure is?
The sidewalk directly in front of the building
Generally, high ornate parapet walls collapse more frequently than lower, less decorative ones. The most dangerous parapet, however, is?
The one constructed as the front wall of a one story structure above several large display windows, the sort found in supermarkets, shopping malls, and rows of stores.
If a parapet wall is solid brick WITHOUT steel reinforcement, it may fall in one small section, with the rest remaining on top of the steel lintel support. But if the parapet wall is tied together with reinforcement rods, the entire wall may collapse, even if only one small section of it is unstable. The most susceptible parapet wall to total collapse during firefighting operations is?
Ornamental cast stone and decorative terra-cotta parapets
As all the trusses begin to fall, the weight of the roof will shift from the trusses to the front and rear parapet walls by way of the hip roof rafters or purlins, which extend from the end bow string trusses to the front and rear parapet walls. The entire front wall will collapse in what fashion?
Inward outward collapse. The upper part falls inward and the lower part falls outward.
Parapet walls often fail during what stage of the fire?
Overhaul stage. After the fire has been weakened and partially destroyed by fire and large caliber master streams.
Today the fire service knows an ordinary masonry wall will fail and cover, with brick and masonry, a distance from the wall equal to 1, 1 1/2, or twice its full height and bricks may bounce and roll farther. If the masonry wall falls because of an explosion or internal pressure, the wall will fall how far?
Outward for a distance equal to twice its height with force, bricks may bounce or roll out farther
The leading cause of FF death by collapse is?
Fire resistance is directly related to?
Its "mass" Bulk and spacing in the floor system.
This reduction of mass and increased spacing reduces fire resistance and allows floors to burn through and fail faster than conventional solid wood floor beams.
The most deadly type of floor collapse is?
a MULTILEVEL floor collapse (progressive floor failure)
A unsupported lean-to floor collapse is caused by?
A bearing wall failure
a V shaped floor collapse is caused by?
A center floor overload
A pancake floor collapse is caused by?
Shock or impact of a heavy falling object
The most dangerous time for a floor collapse is?
The decay stage. Overhauling time of a fire is when collapse danger is highest.
The 3 most common sloping roofs are?
Gable, Gambrel, and Hip
A hip roof has how many primary structural elements?
9, 4 bearing walls 1 ridge and 4 hip rafters
A primary structural element is a structure which supports another structural member. The collapse of a primary structural member may lead to the failure of another part of the building. Ridge and hip rafters and bearing walls are primary structural members found in sloping roof construction. What are the primary structural members in wood floor construction?
Header and trimmer beams
A purlin is?
A timber laid horizontally and perpendicular to support the common rafters of a roof
The 3 most common types of wood construction for sloping roofs are?
Plank and beam
The truss roof has the largest area of unsupported roof deck plank and beam is the next largest area.
Roof coverings can be divided into 2 categories. What are they?
Built up and prepared roof coverings
Roof rotting is often found where?
At the edges, where roofs change slope, and where sloping roofs abut a vertical plane.
Slate and tile roofs have the same dangerous effects as terrazzo or tile floors. What are they?
They conceal the amount of heat, smoke and flame below and then collapse in one large section WITHOUT any warning signs
There are 2 ways a FF can protect themselves from a roof deck collapse. What are they?
Use a roof ladder or a aerial/tower ladder.
When operating at a private home with a sloping roof, it is more effective to remove smoke and heat from the structure by venting what?
Top floor windows rather than cutting a vent opening
All departments should develop SOP's for operations involving sloping roofs. These SOP's should be based on 3 things what are they?
In this order of importance
Because sloping roofs shed water and snow when properly pitched, they may be designed to support more or less of a live load than a flat roof?
A timber is wooden construction larger than 2x4 inch but not large enough to be classified as heavy timber or mill construction. The most common connector is?
The split ring metal connector, which is embedded in prepared depressions on the face of the timber. Its purpose is to relieve the bolts of shearing stress.
A timber truss roof can be built in a variety of ways. They are?
The incline plane truss (gable shape)
The parallel chord truss (flat roof)
and the bowstring timber truss (arch roof)
The bowstring being the most common design
The most dangerous roof system is?
The truss roof system is the most dangerous a FF will encounter.
When attacked by flames the entire truss section may fail as soon as the smallest web member weakens.
Why don't the rear walls fail as the front walls do in bow string roof construction?
The front walls have openings which weaken its load bearing ability and permit fire to spread
In a timber truss building the main fire will be located where?
In the roof structure not the content below
The 3 size up indicators of a truss roof are?
Large space without columns
Mounded roof shape (bowstring only)
Certain occupancies use these type of buildings...supermarkets, bowling alleys, theaters, piers, armories
A truss roof concealed by a ceiling is much more dangerous to firefighters than a truss roof without. TRUE or FALSE?
There can be no extinguishing a fire in a truss space from above. Likewise, you cannot extinguish a fire in a truss from below via a trap door. When fire extends to a timber truss attic space, FF"s should prepare for?
A defensive outside attack and protect exposures
The fire strategy of the 1st arriving engine company arriving at a fire in a timber truss roof without a ceiling should attack the fire directly with a large diameter hose capable of reaching 50 feet. If the first hose line does not control the flames within the 1st few seconds and it appears the fire will increase, interior firefighting should?
Be discontinued and ff's withdrawn
If the 1st hoseline is successful and controls the content fire at floor level. The 2nd hoseline should?
Sweep the underside of the roof
To determine if fire has spread to the roof space of a bowstring truss. a trianglular cut may be made in the sloping front or rear of the roof from?
The safety of an aerial platform
If the web members are not enclosed with plasterboard, vent openings may be made in the front and rear sloping portions of the roof thereby providing cross-ventilation of the entire roof space
If a small fire such as an overheated motor or electrical wiring exists in a bowstring truss roofed attic space that is concealed by a ceiling and the access ladder cannot be located. Quick access can be obtained by making a roof cut opening in the sloping ends of the roof deck. TRUE OR FALSE?
FF's attempting the initial hoseline attach on a fire should be positioned?
Behind a truss section next to the one involved in fire. The reach of the powerful stream will allow them to be out of the collapse zone of a single truss
The large open space required in a place of worship usually indicates?
A timber truss roof.
A church,synagogue,mosque, or temple is a poorly designed and dangerous structure.
One reason an exposed timber truss roof of a place of worship will rapidly burn and collapse is?
It has a wax coating on the surface.
A defensive preplan firefighting strategy should consider a collapse of a steeple, the bell tower, the ceiling, and the timber truss roof, followed by the side walls
Studies have found the most unstable structures in a community are often places of worship. And the part of the place of worship that is most unstable is?
The tower and steeple
Since you only get one chance to extinguish a church fire the 1st hoseline should be the largest hose possible with the greatest reach. Where should this line be stretched?
The initial hoseline is taken in the front or side door and attacks the seat of the fire.
If 2 hoselines don't extinguish the fire ff's should withdraw
An aerial stream should be placed in a corner safe area. The 1st to arrive aerial should be positioned where?
If the house of worship has a rose window this is where it should be positioned to operate.
If the interior must be vented for the advance of the first 2 hoselines, then the stained glass windows will have to be vented first. Which ones?
The ones closest to the fire on both sides.
In many urban areas the rose window and side stained glass windows are covered with unbreakable clear plastic. This creates major venting problems and allows smoke and heat buildup and a subsequent backdraft smoke explosion to occur.
If the interior attack is successful and the fire is extinguished by the interior attack hose teams, ff's should immediately try to?
Open up walls and ceilings near the smoldering fire. In addition, FF's should quickly gain access to the attic space and check and see whether fire has already spread to the large concealed space.
The most dangerous areas during a church fire are?
A,B,D sides because of the church steeple and the interconnection of the roof and side bearing walls.
If fire reaches the attic spaces of most places of worship, it cannot be extinguished with handheld hoselines. TRUE or FALSE?