08 Timber Truss Roof Collapse

Question 1

Three ways FFs can die when operating at fires involving timber truss construction?

Answer 1

1. FFs operating outside the building: When trusses collapse, they can cause a secondary collapse and push out a masonry wall.
2. FFs operating on the roof: Can fall through when burning timber trusses fail
3. FFs operating inside: Can be crushed and burned to death when the collapsing truss roof falls

Question 2

Timber is wooden construction larger than __________ but not large enough to be classified as heavy timber of mill construction.

Answer 2

2x4

Question 3

A timber truss roof can be built in a variety of shapes.

Answer 3

1. Inclined Plane Truss (gable shape)
2. Parallel Chord Truss (flat roof)
3. Bowstring Truss (arch roof)

Question 4

What is the most common of truss designs?

Answer 4

Bowstring Truss

Question 5

What is the most dangerous roof system that a FF will encounter?

Answer 5

Truss construction

Question 6

It is known to collapse during the _____________ of a fire, and it will often cause a secondary collapse of the masonry enclosure walls.

Answer 6

early stages

Question 7

When an IC receives conflicting reports (interior size up vs roof size up), the chief should rely on the ______ report.

Answer 7

Roof. (The roof size-up is more accurate than the interior)

Question 8

In a timber truss building, the main fire will be in the ___________________, not in the content below.

Answer 8

roof structure

Question 9

Three size-up indicators for a truss roof in a building:

Answer 9

1. Large open space without columns
2. A mounded roof (bowstring truss only)
3. Certain occupancies that frequently use truss construction (supermarkets, bowling alleys, garages, theaters, places of worship, auto dealerships, piers, and armories)

Question 10

The fire strategy of a first-arriving engine company at a timber truss roof building without a ceiling should be to do what?

Answer 10

Attack the fire directly with a large-diameter hoseline.

Question 11

In a bowstring truss-roofed building which does not have the web members enclosed with plasterboard, where can vent openings be made?

Answer 11

In the front and rear sloping portions of the roof - providing horizontal cross-ventilation of the entire roof.

Question 12

When a truss roof appears weakened by fire, FFs ordered to evacuate the roof should retreat in what direction?

Answer 12

Perpendicular to the roof trusses (get to another truss section that hasn’t been burned out)

Question 13

What is the key to safety when operating at a fire in a truss constructed building?

Answer 13

Communications

Question 14

What is the most unstable structure in a community?

Answer 14

Places of worship

Question 15

What is the most unstable part of a place of worship?

Answer 15

The steeple and tower.

Question 16

What percentage of fires are extinguished by the first attack hoseline?

Answer 16

95%

Question 17

What is the one window at a church or temple that is high enough and big enough to vent smoke and heat at the upper reaches of a burning place of worship?

Answer 17

The Rose Window

Question 18

What are three reasons to vent the side stained-glass windows at a church?

Answer 18

1. If it remains closed up, it may suffer a smoke explosion that could raise the roof and push out the walls.
2. Fire may flash over when FFs are operating inside
3. Smoke and heat may bank down on FFs searching and operating inside

Question 19

Window venting should start where?

Answer 19

At the top and work down.

Question 20

Can handheld hoselines put out a fire that has reached the attic spaces of most places of worship?

Answer 20

No.

Question 21

Highest collapse hazards at places of worship

Answer 21

1. Bell towers
2. Steeple
3. Ceiling
4. Sidewalls
5. Roof

Question 22

Apse

Answer 22

Part of the church that is a semicircle or U shape wall

Question 23

Chancel

Answer 23

A space reserved for the clergy that includes the altar and the front choir area

Question 24

Nave

Answer 24

A main seating area of the church

Question 25

Rose Window

Answer 25

A large round window at the front of Gothic churches

Question 26

Triforium

Answer 26

A middle story of a church (side balconies)

Question 27

Transept

Answer 27

A space that runs at right angles to the nave and chancel

Question 28

Gothic

Answer 28

Church architecture of 12th century that features a pointed arch