Ch. 8 Timber truss roof collapse

Question 1

A Timber truss roof can be built in a variety of shapes: inclined plane truss (gable roof), Parallel chord (flat roof), or a bowstring truss (arch roof). Which one is the most common?

Answer 1

Bowstring truss roof

Question 2

What are the 3 size up indicators for a truss roof?

Answer 2

• A large open space without columns,
• A mounded roof shape(for bowstring truss roofs only),
• Certain occupancies: supermarkets, bowling alleys, garages, theaters, places of worship, armories, piers, auto dealerships.

Question 3

At a fire in a bldg. with a bowstring truss roof, where the IC is getting conflicting reports regarding the seriousness of the fire from the inside members versus the roof level members. The IC should be guided by the report from?

Answer 3

The roof level members

Question 4

When a bldg. has a timber truss concealed by a ceiling, the access to the truss attic space is by a remote ladder enclosed in a closet leading up to a trap door in the ceiling. Units can easily find this ladder and trap door and get into the attic space and extinguish a serious fire.
True of False

Answer 4

False
The chances are slim to none. THERE CAN BE NO EXTINGUISHMENT FROM BELOW THE BURNING TRUSS THROUGH A TRAP DOOR IN THE CEILING.

Question 5

When a fire has control of a timber truss roof concealed by a ceiling opening the ceiling from below and extinguishing it with hose streams is rare. Why is this procedure not used?

Answer 5

Hose streams directed back and forth from below would be broken up by the purlins making the extinguishment effect minimum.

Question 6

Can we attack a timber truss fire concealed with a ceiling from above?

Answer 6

THERE IS NO EXTINGUISHING A FIRE IN A TRUSS SPACE FROM ABOVE.

Question 7

When a fire has control of a timber truss roof concealed by a ceiling, we must prepare for what type of attack and protect what?

Answer 7

Prepare for a Defensive attack and protect exposures.

Question 8

If units arrive to find a fire in a timber truss roof bldg. without a ceiling. The 1st arriving engine should attack the fire directly with a large caliber stream capable of reaching distances of 50 ft. If this 1st hose line does not control the flames within the first ____ _______ of water discharge & it appears the fire will increase, interior firefighting shall be discontinued.

Answer 8

Few Seconds

Question 9

When truss members are enclosed, if a serious fire threatens collapse of the roof, the timber trusses will fail one at a time.
True of false.

Answer 9

True

Question 10

If roof stability is unaffected by fire conditions, FF’s can be committed to the roof for what actions?

Answer 10

To remove skylights and scuttles and then leave the roof area immediately

Question 11

In a building without ceiling and the fire is at the floor level or in a single truss and is successfully controlled, and the fire appears that it will not spread, a 2nd large diameter line shall be stretched and operated where?

Answer 11

It should sweep the underside of the roof area

Question 12

In a structure with a Bowstring truss roof ventilation holes may be made to provide; cross ventilation of the roof space (if the web members are not enclosed), quick access to the enclosed attic area for a small fire, an exterior hose line operated thru the vent opening, an exterior view into the roof area to check for fire spread.
Where are these ventilation openings made?

Answer 12

They are made in the sloping front or rear portions of the roof.

Question 13

If FF’s that are operating on the roof are ordered to evacuate they should evacuate towards what walls in what direction from the truss sections?

Answer 13

They should evacuate towards the front or rear walls, perpendicular to the truss sections.

Question 14

In a place of worship what is the most unstable part of the structure?

Answer 14

The tower and the steeple

Question 15

If a church fire is extinguishable, the 1st line should be taken in the front or side door to attack the seat of the fire and extinguish it. What diameter hose should the 1st and 2nd lines be?

Answer 15

Stretch the largest diameter hose, maneuverability is not a factor. what is needed is large amounts of water, and a high pressure stream with maximum reach. The 2nd line should immediately back up the 1st line.

Question 16

As soon as the flames are knocked down at a fire in a Place of Worship what needs to be checked for concealed fire spread? (2 answers)

Answer 16

The Walls and Attic

Question 17

Can we take a defensive attack with the hose lines INSIDE a church?

Answer 17

We NEVER take defensive attack from the inside.

ALWAYS the outside

Question 18

Primary venting should be what at a Church or Temple?

Answer 18

Primary venting at a church or temple should be the Rose window. The Rose window is the large stained glass window at the upper reaches of the church front. The Rose window should be vented from a raised bucket-the entire window shall be vented. This is the one window that is high and big enough to vent smoke and heat from the upper reaches of the church, it can also provide access for a aerial master stream to discharge water into the upper portions of the bldg.

Question 19

After primary venting of the Rose window, a decision must be made regarding the venting of the side stained glass windows. If the interior MUST be vented for the advance of the 1st two hose lines, then first vent the stained glass on both sides of the bldg. In regards to the fire where do we vent these stained glass windows?

Answer 19

Nearest to the fire

Question 20

What exposures are the most dangerous areas during a place of worship fire?

Answer 20

Exposures 1,2, and 4 because of the steeple and the interconnection of the roof and the side walls.

Question 21

The steeple is the tapered pointed structure on top of the church tower that has a cross at the tip. A temple may have a dome at the top. Which is more unstable the steeple on a tower or a domed tower?

Answer 21

The steeple tower is more unstable.

Question 22

What shall be our SOP when fire has entered the attic space in a place of worship?

Answer 22

Fire reaching the attic space of a place of worship cannot be extinguished by hand held lines because there is only one small door and no possibility to vent. FF’s will have to be withdrawn and a defensive attack with master streams deployed.