Dunn Chapters 5,6,7,8

Question 1

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?

Answer 1

The sidewalk directly in front of the building

Question 2

Generally, high ornate parapet walls collapse more frequently than lower, less decorative ones. The most dangerous parapet, however, is?

Answer 2

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.

Question 3

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?

Answer 3

Ornamental cast stone and decorative terra-cotta parapets

Question 4

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?

Answer 4

Inward outward collapse. The upper part falls inward and the lower part falls outward.

Question 5

Parapet walls often fail during what stage of the fire?

Answer 5

Overhaul stage. After the fire has been weakened and partially destroyed by fire and large caliber master streams.

Question 6

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?

Answer 6

Outward for a distance equal to twice its height with force, bricks may bounce or roll out farther

Question 7

The leading cause of FF death by collapse is?

Answer 7

Floor failure

Question 8

Fire resistance is directly related to?

Answer 8

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.

Question 9

The most deadly type of floor collapse is?

Answer 9

a MULTILEVEL floor collapse (progressive floor failure)

Question 10

A unsupported lean-to floor collapse is caused by?

Answer 10

A bearing wall failure

Question 11

a V shaped floor collapse is caused by?

Answer 11

A center floor overload

Question 12

A pancake floor collapse is caused by?

Answer 12

Shock or impact of a heavy falling object

Question 13

The most dangerous time for a floor collapse is?

Answer 13

The decay stage. Overhauling time of a fire is when collapse danger is highest.

Question 14

The 3 most common sloping roofs are?

Answer 14

Gable, Gambrel, and Hip

Question 15

A hip roof has how many primary structural elements?

Answer 15

9, 4 bearing walls 1 ridge and 4 hip rafters

Question 16

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?

Answer 16

Header and trimmer beams

Question 17

A purlin is?

Answer 17

A timber laid horizontally and perpendicular to support the common rafters of a roof

Question 18

The 3 most common types of wood construction for sloping roofs are?

Answer 18

Timber truss
Plank and beam
Rafter

The truss roof has the largest area of unsupported roof deck plank and beam is the next largest area.

Question 19

Roof coverings can be divided into 2 categories. What are they?

Answer 19

Built up and prepared roof coverings

Question 20

Roof rotting is often found where?

Answer 20

At the edges, where roofs change slope, and where sloping roofs abut a vertical plane.

Question 21

Slate and tile roofs have the same dangerous effects as terrazzo or tile floors. What are they?

Answer 21

They conceal the amount of heat, smoke and flame below and then collapse in one large section WITHOUT any warning signs

Question 22

There are 2 ways a FF can protect themselves from a roof deck collapse. What are they?

Answer 22

Use a roof ladder or a aerial/tower ladder.

Question 23

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?

Answer 23

Top floor windows rather than cutting a vent opening

Question 24

All departments should develop SOP’s for operations involving sloping roofs. These SOP’s should be based on 3 things what are they?

Answer 24

Life safety
Fire containment
Property protection
In this order of importance

Question 25

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?

Answer 25

LESS

Question 26

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?

Answer 26

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.

Question 27

A timber truss roof can be built in a variety of ways. They are?

Answer 27

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

Question 28

The most dangerous roof system is?

Answer 28

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.

Question 29

Why don’t the rear walls fail as the front walls do in bow string roof construction?

Answer 29

The front walls have openings which weaken its load bearing ability and permit fire to spread

Question 30

In a timber truss building the main fire will be located where?

Answer 30

In the roof structure not the content below

Question 31

The 3 size up indicators of a truss roof are?

Answer 31

Large space without columns
Mounded roof shape (bowstring only)
Certain occupancies use these type of buildings…supermarkets, bowling alleys, theaters, piers, armories

Question 32

A truss roof concealed by a ceiling is much more dangerous to firefighters than a truss roof without. TRUE or FALSE?

Answer 32

TRUE

Question 33

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?

Answer 33

A defensive outside attack and protect exposures

Question 34

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?

Answer 34

Be discontinued and ff’s withdrawn

Question 35

If the 1st hoseline is successful and controls the content fire at floor level. The 2nd hoseline should?

Answer 35

Sweep the underside of the roof

Question 36

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?

Answer 36

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

Question 37

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?

Answer 37

TRUE

Question 38

FF’s attempting the initial hoseline attach on a fire should be positioned?

Answer 38

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

Question 39

The large open space required in a place of worship usually indicates?

Answer 39

A timber truss roof.

A church,synagogue,mosque, or temple is a poorly designed and dangerous structure.

Question 40

One reason an exposed timber truss roof of a place of worship will rapidly burn and collapse is?

Answer 40

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

Question 41

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?

Answer 41

The tower and steeple

Question 42

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?

Answer 42

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

Question 43

An aerial stream should be placed in a corner safe area. The 1st to arrive aerial should be positioned where?

Answer 43

If the house of worship has a rose window this is where it should be positioned to operate.

Question 44

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?

Answer 44

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.

Question 45

If the interior attack is successful and the fire is extinguished by the interior attack hose teams, ff’s should immediately try to?

Answer 45

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.

Question 46

The most dangerous areas during a church fire are?

Answer 46

A,B,D sides because of the church steeple and the interconnection of the roof and side bearing walls.

Question 47

If fire reaches the attic spaces of most places of worship, it cannot be extinguished with handheld hoselines. TRUE or FALSE?

Answer 47

TRUE

Question 48

Primary venting at a place of worship includes?

Answer 48

Venting the rose window at the front of the building. Primary venting also includes the stained glass windows near the fire on both sides of the structure.