13- Truck Company S&T- Vertical Ventilation Flashcards
Before stepping onto any roof, firefighters should ___(observe the condition of) and _____(test the condition of) the roof and they should continue to do so as long as they are on the roof.
Read (observe the condition of)
Sound (test the condition of)
Whenever firefighters are on a roof, the building should be laddered on at least ___ sides.
(it should be laddered on all sides if resources permit)
Two
If firefighters must walk the ridge of a peaked roof, they should walk:
With one foot on either side of the ridge
In general, the strongest points of any roof are:
*3 answers
-Where the roof meets the outside walls
-Directly over roof supports
-At ridges or valleys
In general, the weakest points of roofs are:
Between the supports
Once firefighters are on the roof, they should:
Test the roof by gently bouncing on it while holding onto the ladder or parapet wall with one hand.
A key factor in opening roofs safely and efficiently is knowing the location and extent of the ___ and the location and direction of the ____.
Fire ; Rafters
If sounding does not reveal the location and direction of the rafters, a diagonal cut through the roof covering can be made with a chain saw or rotary saw at an angle of __ degrees to any exterior wall. The blade will usually encounter a rafter before the cut is __ feet long.
45 degrees
3 feet long
A triangular hole, also know as a/an _____ ____, can be completed to determine spacing, roof thickness, and possible fire conditions in the attic.
Inspection Hole
It is recommended that a clear space of at least __ feet be maintained in all directions from anyone using a cutting tool in vertical ventilation.
10
The most common cutting tools used for vertical ventilations are:
*3 answers
Rotary Saw, Chain Saw, Pick Head Axe
The most common pitch on residential roofs in areas with mild climates is:
5-in-12 roof (5 pitch)
In gable roof assemblies, the rafters are commonly spaced at __ to __ inches on center.
16 to 24
Pitched roofs should be vented at the ____ point, on the _____ side, directly over the fire or as close to it as safely possible.
Highest point ; Leeward side
The ventilation open on pitched roofs should be cut ____ to the rafters and _____ to the ridge.
Parallel ; Perpendicular
The ventilation exit opening should be AT LEAST __x__ feet, and in many cases may need to be larger.
4x4 feet
____ Roofs are commonly supported by horizontal joists or rafters similar to the joists used in floor systems.
Flat
Some types of fire-resistant plywood delaminate and weaken over time, resulting in a deck that may not support the weight of a firefighter even if it has not been damaged by a fire. Identifying these hazardous roofs during ____ ____ ____ is CRITICAL to firefighter safety.
Preincident Planning Surveys
Unprotected metal deck roofs can be expected to fail within _______ minutes of flame impingement. Because the heat of a fire will soften metal and make it more pliable, metal decking around roof vents and other openings may not support the weight of a firefighter.
A few
The single biggest hazard of arched roofs is:
The danger of sudden and total collapse (often without warning).
The bridging effect of parallel chord trusses causes the top chord to always be in _____ and the bottom chord in ______.
Compression ; Tension
Some wooden components can be held together by sheet metal gusset plates, aka gang nails. The gusset plates can vary in size, but ____ inch prongs are common.
3/8” prongs
Common pitched roof truss configurations are the ____, ____, and ____ trusses.
Howe, Pratt, and Fink
Wooden I-Beams consist of three main components: A top chord, a bottom chord, and a solid ___ inch plywood or OSB web.
3/8”
