Truck Flashcards
Ventilation definition:
“systematic” removal of heat, smoke, and fire gases from a structure, replacing it with cooler, clean, fresh air
Effective ventilation will accomplish four main objectives:
- save lives
- assist in firefighter access
- control the horizontal spread of fire
- reduce the possibility of flashover/backdraft
Two methods of horizontal ventilation:
- natural
- positive pressure
What is the key to effective roof ventilation?
knowledge of rafter type and rafter direction
When operating on a lightweight truss roof, or suspected lightweight truss roof, the ventilation team shall never:
conduct ventilation directly over the fire
Two types of ventilation holes:
- heat hole (offensive)
- strip (defensive)
What must occur with strip ventilation? (Trench)
A heat hole
Heat hole must be cut first to slow the horizontal spread of the fire
A head cut must be performed on roofs covered with?
plywood and diagonal sheathing
Kerf cut definition:
single cut made through the roof decking, the same width as the saw blade. Not as effective but can be used as an alternative to using a smoke indicator hole
Plug cut definition:
triangular piece of roof comp removed to expose the sheathing, used to determine sheathing type and roof composition thickness
Skim cut definition:
Used when?
light cut through covering and plywood sheathing, skim the top of the rafters, used on panelized roofs when you louver off a purlin
Smoke indicator hole definition:
triangle cut through sheathing and roof material, indicator smoke/fire conditions, should be placed along the path of access/egress every few yards
45 degree inspection cut definition:
used to determine rafter type/direction, will also tell you sheathing type, thickness of roof comp, and act as smoke indicator
Saw operator should cut a min of ___ dice cuts prior to the puller removing sheathing
3
Always leave a min of ___ un pulled section between the cutter and the puller? (when dicing)
1
Panelized roof cutting techniques and mode of operation:
- drop method (offensive)
- pull back method (offensive)
- offensive louver (offensive)
- louver off lam/main beam (defensive)
- louver off purlin (defensive)
Book 29-
size up consists of 3 operations:
- analyze situation
- decide on plan (strategy)
- put plan into operation (tactics)
Conducting a building size up, focus on:
- construction style
- roof style
- construction method
- age of building
Ability to accurately estimate the amount of time that a structure can be considered structurally strong is dependent on:
- type of construction
- how long the fire has been building
- fire intensity
Gable roof, strength/hazards:
strengths: ridge and exterior walls
haz: trusses w/ metal gusset plates = short burn time and potential failure/collapse
T/F
Plywood will burn/fail at a faster rate than sheathing
True, plywood offers minimal resistance to fire
Hip roof, strengths/hazards:
strengths: ridge, valley, hip, and exterior walls are areas of strength
haz: if covered w/ tile, will need to be removed prior to cutting
Bridge truss, strengths/hazards:
strengths: well constructed, easily identifiable by its sloping ends
haz: strength is dependent on size of lumber and span of trusses. underside is usually common to interior of commercial warehouse
Bridge truss roofs usually found on:
commercial buildings constructed between 30s-40s. usually heavy grade construction
Straight sheathing usually used prior to ___, diagonal sheathing utilized after
1933
Bowstring arch roofs usually found on:
both small and large commercial structures, popular during 30s, 40s, 50s
Bowstring arch, strengths/hazards:
strengths: usually well constructed
haz: underside is usually common to the interior of commercial warehouse, usually fails in sections
Lamella arch roofs common on:
gymnasiums, large buildings used for rec. activities, supermarkets, etc
Lamella, strengths/hazards:
strengths: solidly built
haz: total collapse may occur if fire removes more than 20% of roof structure
Tied truss arch roofs use:
metal tie rods to offer lateral support for the exterior walls
tie rods used below each arch member
Tied truss arch, strengths/hazards:
strengths: utilized large size lumber
haz: early failure of metal tied rods
Sawtooth roofs used on:
commercial building to yield more light and ventilation
constructed same today as it was in the 30s/40s
Sawtooth strengths/hazards:
strengths: well constructed, easy to ventilate
haz: underside is open and exposed to the structure
Difference between conventional flat roof and lightweight flat roof:
similar in design, rafters replaced w/ lightweight construction
Conventional flat roof, strengths/hazards:
strength: perimeter of the building. susceptibility to fire is dependent on size of rafters
haz: determined by rafter size/span/spacing, presence of metal hangers
Newer conventional flat roofs will be covered with ___ instead of ___
plywood instead of sheathing
Wooden I beam roof, strengths/hazards:
strength: perimeter of the building
haz: little time for the 3/8 inch stem to burn, weaken, cause collapse. expect rapid failure when exposed to fire
Open web roof, strengths/hazards:
strength: exterior of the building
haz: truss chords will take little time to burn/weaken/fail, expect rapid failure
Metal gusset plate roof, strengths/hazards:
strength: where trusses cross/terminate on outside bearing walls
haz: little time to burn/weaken/collapse, rapid and total collapse is common
Panelized roof, 4 major components:
- beams
- purlins
- 2x4 joists (rafters)
- 2 inch plywood decking
Panelized roof, strengths/hazards:
strengths: beams, purlins, perimeter
haz: weakening and/or collapse with failure of large portions of the roof under heavy fire conditions
Open web bar joist roof, strengths/hazards:
strengths: perimeter
haz: metal exposed to fire/heat (loses strength at 1000 deg.) will expand, twist and probably fail
Lightweight concrete roof are utilized when?
additional insulate properties are desired (next to airports/freeways)
Lightweight concrete roof strength/hazard:
strength: structurally sound, resistive to fire
haz: difficult to penetrate w/ chain saw
What type of roof construction should you expect to see on a concrete tilt up?
lightweight
Indications of a pre 33, unreinforced masonry:
- sand/lime mortar
- rafter tie plates
- king row
- inset windows
What event led to post 33 construction?
LB earthquake
What event led to post 59 construction?
Tehachapi earthquake
What event led to post 71 construction?
Sylmar earthquake
Unreinforced masonry floor and roof joists were originally designed to:
pull out from the walls during a fire, preventing wall collapse
What is a facade?
“external attics”
usually open or common to the attic space
What do rafter tie plates indicate?
location of roof rafters and identify the roof line
Ballon construction hazard?
vertical spread of fire in the walls up to the above floors/attic space due to the absence of horizontal fire stops
