Chapter 13

Question 1

Firefighters must beware of the possibility of falling onto roofs from high parapet walls, of falling off roofs because of tripping over low parapets, and of poor footing on steep roofs. They must also be aware of the potentially dangerous levels of electrical power (up to __ volts DC, at up to __ amps) inherent in rooftop solar panels.

Answer 1

600

8

Question 2

Most roof assemblies employ a parallel rafter system with rafters spaced from __ inches on center, spanning the shortest distance between structural members or bearing walls.

Answer 2

12 to 24

Question 3

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.

Answer 3

45

3

Question 4

If, after a rafter is located, its direction is still unknown, a cut parallel to a sidewall should be made, crossing the first cut. This cut should be __ feet long.

Answer 4

2 to 3

Question 5

While departmental SOPs must always be followed, 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.

Answer 5

10

Question 6

A roof that decreases 5 inches vertically for each foot horizontally from the ridge would be described as a __ roof, which is the most common pitch on residential roofs in areas with mild climates

Answer 6

5-in-12

Question 7

Gable roofs:
The ridge and rafters are often __-inch lumber or larger in stick-built roofs (those built on site), but in prefabricated roof trusses these components are commonly __-inch depending upon the span.

Answer 7

2x6

2x4

Question 8

Gable Roofs:
In both types of roof assemblies, the rafters are commonly spaced at __ inches on center.

Answer 8

16 to 24

Question 9

Hip roof construction consists of a ridge beam with conventional rafters running perpendicular to the ridge and hip rafters running from the ends of the ridge beam, at a compound angle of __ degrees laterally and at some lesser vertical angle down to and beyond the outside walls at the corners.

Answer 9

45

Question 10

Bridge-Truss Roof:
When constructed of wood, the trusses are often made from __-inch lumber, and vertical metal tie rods may be used for additional support.

Answer 10

2x12

Question 11

Bridge-Truss Roof:
Joists are usually _ x _-inch or _ x _-inch lumber covered with _ x _-inch sheathing.

Answer 11

2x6; 2x8

1x6

Question 12

Bridge-Truss Roof:

Truss spacing may be as much as _ to _ feet on center.

Answer 12

16 to 20

Question 13

The sawtooth roof consists of a series of small pitched roofs similar in shape to the teeth of a saw. The rafters are _ x _ inch lumber or larger and use wood or metal supports for bracing.

Answer 13

2x8

Question 14

Venting pitched roofs:

The ventilation exit opening should be at least _ x _ feet, and in many cases may need to be larger.

Answer 14

4x4

Question 15

Flat Roofs:

This type of roof ordinarily has a slight slope of __ pitch or less from the front toward the rear of the building to allow drainage.

Answer 15

Two-in-twelve

Question 16

In the inverted roof, the main roof joists are set at the level of the ceiling, and a framework of _ x _-inch members is constructed above the main joists.

Answer 16

2x4

Question 17

The design of the inverted roof often creates a concealed space several __ in height between the ceiling and the roof deck.

Answer 17

Feet

Question 18

Wooden deck roofs may present a hazard if lightweight plywood or OSB decking is used. Panels of __-inch thickness offer little fire resistance, but may be difficult to remove for tactical ventilation.

Answer 18

3/8 to 5/8

Question 19

Because it is difficult and time consuming to cut concrete roofs that are more than __ inches thick, they are often designed with built-in access panels that can be lifted out in an emergency.

Answer 19

4

Question 20

Poured gypsum roofs consist of bar joists or I-beams with brackets welded to the joists. Gypsum board is placed on the brackets and is covered with a layer of gypsum cement up to __ inches thick to which wire mesh reinforcement is added.

Answer 20

2 1/2

Question 21

Inverted flat roofs create special hazards as well. This design also creates a concealed space, often several feet in height, which includes many unprotected wooden structural members. Heavy fire conditions can burn quickly through the __-inch supporting members, causing the roof deck to collapse onto the roof joists.

Answer 21

2x4

Question 22

Many buildings with flat roofs also have parapet walls that can be a help as well as a hazard to firefighters during ventilation operations. These walls may extend from a few __ to several __ above the roof surface.

Answer 22

Inches

Feet

Question 23

When cutting the ventilation opening, firefighters should work with the wind at their backs. They should start by making a cut across the leeward end so that the smoke will blow away from them as they continue to work. This should be followed by making parallel side cuts at least __ feet apart between the rafters

Answer 23

4

Question 24

Arched Roofs:

Typically, arches are spaced at __ foot centers.

Answer 24

16 to 20

Question 25

Bowstring Truss Arch:
The top chords of these arches are usually laminated __-inch or larger lumber

Answer 25

2x12

Question 26

Bowstring Truss Arch:
The purlins (usually __ inches) are covered by __-inch or larger sheathing and composition roofing material.

Answer 26

2x10

1x6

Question 27

The trussless arch roof uses massive arches of steel, concrete, or laminated wood buttressed into the ground at each end. These arches may be spaced between __ feet apart.

Answer 27

16 and 20

Question 28

The lamella roof is another type of trussless arch made up of an interlocking geometric framework on which plank sheathing is laid. The framework is usually constructed of dimensional lumber in which __-inch wooden members are bolted together at the intersections with steel gusset plates.

Answer 28

2x12

Question 29

The lamella roof system shares many characteristics with the bowstring-type roofs, and the same operational and safety considerations apply. However, when __ percent of a lamella roof burns away, sudden failure of the remainder of the roof is likely.

Answer 29

10 to 20

Question 30

Because of the rising costs of labor and building materials, lightweight roof construction has become much more common in recent years. In many modern buildings, heavy timber and plank sheathing have given way to laminated beams and __-inch lumber covered by __-inch plywood or OSB, regardless of building size.

Answer 30

2x4

1/2

Question 31

Panelized roof construction consists of laminated beams of various sizes – commonly _ x _ inches – that span the length or width of the building.

Answer 31

6 x 36

Question 32

Panelized Roofs:

Additional wooden or steel posts may provide support at intervals along the span. The beams may be bolted together to form lengths well in excess of __ feet and may be spaced between _ x _ feet apart.

Answer 32

100

12 and 40

Question 33

Panelized Roofs:

Wooden purlins, usually _ x _ inches with metal hangers are installed on __-foot centers between and perpendicular to the beams.

Answer 33

4 x 12

8

Question 34

Panelized Roofs:

Wooden rafters or sub-purlins, usually _ x _ inches by __ feet, are installed with metal hangers on __-foot centers between and perpendicular to the purlins.

Answer 34

2 x 4; 8

2

Question 35

Wooden parallel chord trusses. Some parallel chord trusses are constructed of wooden components held together with sheet metal gusset plates, also known as gang nails. These gusset plates vary in size, thickness, and depth of penetration, but __-inch prongs are common.

Answer 35

3/8

Question 36

Wooden/metal Trusses:

The web members are usually made of __-inch cold-rolled steel tubing with the ends pressed flat.

Answer 36

1

Question 37

Wooden/metal Trusses:

Normal spacing of these trusses is __ feet on center.

Answer 37

2

Question 38

Pitched Roof Trusses:

Like many parallel chord trusses, the most common pitched roof trusses are prefabricated of relatively small dimension wood, usually _ x _-inch lumber held together with metal gusset plates where the components intersect.

Answer 38

2 x 4

Question 39

Pitched Roof Trusses:

Even without the support of interior walls, spans of up to __ feet are possible using 2- × 4-inch components.

Answer 39

55

Question 40

Pitched Roof Trusses:

The most common spacing between these trusses is _ to _ feet on center, and __-inch plywood or OSB is commonly used as sheathing.

Answer 40

2 to 4

1/2

Question 41

Wooden I-beams consist of three main components: a top chord, a bottom chord, and a solid /-inch plywood or OSB web.

Answer 41

3/8

Question 42

Wooden I Beams:

The chords may be made of _ x _-inch lumber, _ x _-inch lumber, or a wooden laminate called micro-lam.

Answer 42

2 x 3

2 x 4

Question 43

Wooden I Beams:

Common spacing for this type of beam is __ feet on center, and the area where the beams rest on the outside walls is the strongest point

Answer 43

2

Question 44

Roof coverings are classified in NFPA® __, Guidelines on Roof Coverings and Roof Deck Construction.

Answer 44

203

Question 45

Sheathing — First layer of roof covering laid directly over the rafters or other roof supports. Sheathing may be plywood, chipboard sheets, or planks that are butted together or spaced about __ inch apart. Also called Decking or Roof Decking.

Answer 45

1

Question 46

Shakes and shingles are usually nailed to wooden _ x _-inch or _ x _-inch plank sheathing with a space of about 1 inch between the planks.

Answer 46

1 x 4

1 x 6

Question 47

Urethane/isocyanate foams are applied to roofs in two forms. One is in the form of _ x _-foot sheets of foam insulation. The other form is called foamed-in-place applications.

Answer 47

4 x 8

Question 48

Concrete, clay, or ceramic tile roofs use tiles that are usually flat, interlocking pieces that hook over _ x _-inch battens (sometimes called furring strips) nailed to the sheathing or directly to the rafters.

Answer 48

1 x 2

Question 49

Light-Gauge Metal or Fiberglass
This type of roof covering consists of aluminum, fiberglass, or _ to _ gauge steel panels over a wooden or metal substructure.

Answer 49

18 to 20

Question 50

Steel Clad roofs:

The first type consists of / x _ inch wide steel straps laid out side-by-side on the roof. A second layer of straps crosses the first layer at right angles, and the straps are welded together at each intersection. The grid thus formed leaves small openings of from _ to _ inches square.

Answer 50

1/4 x 2

6 to 8

Question 51

Steel Clad Roofs:

The second type consists of _ x _-foot sheets of steel, ranging from / x / inch thick, being laid over the entire roof surface. The plates are then welded together to form a continuous layer of steel. Again, hot tar is applied for weather resistance.

Answer 51

4 x 8

1/8 to 1/4

Question 52

Steel-clad roofs hold in heat and smoke, promote the development of flash- over and backdraft conditions, impede ventilation efforts, and increase the chances of roof collapse due to the added weight. Because a 1/4-inch steel plate weighs about __ pounds per square foot, a 20- × 50-foot roof would have approximately __ pounds added to it.

Answer 52

10

10,000

Question 53

The time required to enlarge an opening of inadequate size or to cut several smaller holes is greater than that required to make one large opening. One 8- × 8-foot opening is equal in area to __ 4- × 4-foot holes

Answer 53

four

Question 54

Center Rafter Cut
This method is sometimes referred to as cutting with the rafters. With a rafter spacing of __ feet on center, the hole will be approximately __ feet wide and as long as is necessary.

Answer 54

2

4

Question 55

Center Rafter Cut:
Make the first cut parallel to rafter A, cutting __ inches from the rafter to miss any metal joist hangers.

Answer 55

2 to 3

Question 56

A center-rafter cut works equally well on pitched or flat roofs. This is particularly true in newer buildings with _ x _-inch trusses set on __-inch centers.

Answer 56

2 x 4

24

Question 57

Dicing:

Make the second cut about __ feet long, centering it between rafters A and B.

Answer 57

4

Question 58

Rolling back Panelized roofs:

When finished, the opening will measure approximately __ feet wide times the distance between roof supports, which may be from _ to _ feet.

Answer 58

8

12 to 40

Question 59

Trench ventilation is accomplished by cutting an opening in the roof, at least __ feet wide, across the entire width of the building.

Answer 59

4