Book 29: CHAPTER 2 BUILDING CONSTRUCTION Flashcards
As architects reduce the mass and change the chemical composition of building materials, we are losing one of our most valuable factors:
time.
Firefighters who can recognize the strengths and hazards of buildings and roofs will increase their
efficiency and safety.
A working knowledge of building construction not only provides the necessary expertise to conduct a quick and accurate size-up of a structure, it also provides the foundation for effective, timely, and safe operations in the following areas:
Structural Integrity
Ladder Placement
Forcible Entry / Search and Rescue
Ventilation Feasibility
how many types of operations ae there? and what are they
2
Offensive
Defensive
(estimate of the situation) is a mental evaluation that assists in determining a course of action and the methods necessary to accomplish a desired goal.”
size up
a size-up consists of three operations as follows
Analyze the situation.
Decide on a plan. (strategy)
Put the plan into operation.(tactics)
“analyzing the situation.” When this portion of a size-up is applied to a structure fire, one of the first considerations should be the _____and______of the building.
type and construction
the type and construction of the building. These two factors will indicate:
Rate of burning.
Possible avenues of fire spread. (false ceilings, multiple attics, facades, etc.)
Problems that will have a direct impact on efforts to confine a fire.
Structural integrity.
Time necessary to conduct safe fireground operations.
Our size-up will focus on the following areas:
Construction Styles
Roof Styles
Construction Methods
Age of the Building.
how many construction methods are there and what are they
4
metal concrete
masonry
frame/stucco
curtain
utilizes structural members that depend on size for strength. The greater the span for a structural member, the larger it has to be to support a given load. Additionally, does not usually depend on the sum total of all structural parts or members for its strength. Structural members depend on their size for strength.
Conventional construction
SIZE = STRENGTH
This can be easily demonstrated by considering _____/______ Structural members may be _____ inches for strength.
mill/timber
8x8
The strength of the individual structural member is dependent on the total sum of the other members; therefore, if one member fails, others may fail.
LIGHTWEIGHT CONSTRUCTION
LIGHTWEIGHT CONSTRUCTION . Strength is obtained from multiple members that are in ______and______
compression and tension
A single lightweight truss structural member can span _____feet and may be comprised of ____ in compression and tension to form an integral unit. Although this structural member is strong, the size of the individual members are relatively small, requiring less time for structural collapse when exposed to heat or fire.
70’
2x4s
the ability to accurately estimate the amount of time that a structure can be considered structurally strong is dependent on the following factors:
Type of Construction.
How long the fire has been burning.
Fire Intensity
For size-up considerations, roof styles can be divided into the following categories (6):
Gable
Hip
Flat
Bridge Truss
Arch
Sawtooth
A frame configuration of conventional or ordinary construction that consists of a ridge board and rafters that cross the outside walls.
GABLE ROOF
GABLE ROOF
Rafters are usually ______inches or larger and are usually __inches to ___ inches “on-center.”
2x6
16 to 24
GABLE ROOF
Additional support is provided by _____ and _____. This roof is found in _____ to steep pitch configurations.
collar beams and ceiling joists
semi-flat
GABLE ROOF
As detailed earlier in this section, 2 x 6 inch rafters (spaced up to ___inches “oncenter” for steep pitched roofs) were commonly utilized for roof structural members. Additionally, the ridge was comprised of ____ inch ridge board or the lack of a ridge board which resulted in the ____ inch rafters butted together.
36’’
1x6’’
2x6’’
GABLE ROOF
Lightweight construction utilizes ____or ____ inch wood trusses held together by ________ connectors. Trusses share common features such as top chords, bottom chords, and ______.
2x3 or 2x4
metal gusset plate
webbing
Gable (lightweight)
Metal gusset plate connectors may vary in size, thickness, and depth of penetration. The most common are ___ gauge steel plates with prongs that produce ____ inch penetration.
18
3/8
Gable (lightweight)
The _____ of the truss has replaced the 2 x 4 inch (or larger) ceiling joist found in conventional construction.
bottom chord
Gable (lightweight)
A point of interest with this type of lightweight construction (which also applies to open web and wooden “I” beam construction) is the fact that truss members may only be supported at their _______ (unless used as a cantilever truss).
outside edges
Gable (lightweight)
Interior partition walls may not support the truss at any point along the bottom chord. Eighteen-gauge “_________” may be found nailed to the bottom chord (every ___ to___ trusses) and top plate of interior walls.
roof truss clips
3-5
Roof truss clips provide some stability for
interior partition walls
Gable (lightweight)
In this configuration, interior partition walls could be classified as “_________.” Common “on-center” spacing for truss rafters is __ inches.
free standing
24’’
GABLE ROOF
Strengths
Conventional construction utilizes ______ and ____ of 2 x 6 inches or larger. The strong areas of this roof are ?
Ridgeboards and rafters
the ridge and the area where the rafters cross the outside walls.
GABLE ROOF
Hazards
Trusses are under tension and compression and when the bottom chord or webbing fails trusses will fail. Rapid collapse is common. When metal connector plates and surrounding wood are exposed to fire, the connector plates will quickly fail by?
pulling out of the wood.
GABLE ROOF
Hazards
Newer roofs use __ or __ inch plywood as a decking instead of 1 x 4 inch or 1 x 6 inch space sheathing. Plywood will burn and fail at a faster rate than sheathing, and offers minimal resistance to fire. ____, ___ and ____ board are also currently utilized as a decking in an effort to reduce building costs and can be more hazardous than plywood.
3/8
1/2
particle, chip and strand
Similar to the gable roof. Notice the lack of the A-frame configuration. Ends of the roof terminate in a “hip” configuration.
HIP ROOF
HIP ROOF
Conventional or ordinary construction consists of a _____, ______, from the ______down to and across the corners at the outside walls.
ridge board, hip rafters
ridge board
HIP ROOF
are utilized where two roof lines join together. _____ and _____ rafters complete the structural members.
valley rafters
jack and common
HIP ROOF
The ridge board and rafters are usually ___ inches or larger. Rafters are usually ____to___ inches “on center,” similar to the gable roof. “Rough cut” ___ or ____ inch rafters __ inches “on-center” were also utilized in older wood frame structures with steep pitched roofs.
2x6
16 to 24’’
2x3 or 2x4
36’’
HIP ROOF
Strengths
Ridge board, valley rafters, hip rafters, and the area where rafters cross the outside walls are areas of strength. In conventional construction, ridges and rafters are 2 x 6 inches or larger.
These roofs are found on various types and sizes of commercial buildings primarily constructed during the 1930’s and 1940’s….This roof is easily identified by its characteristic sloping ends.
BRIDGE TRUSS ROOF
BRIDGE TRUSS ROOF
Wooden truss members are built from
2 x 12 inch lumber.
BRIDGE TRUSS ROOF
_______rods may be used vertically for additional support. Rafters are ___ inches or larger and covered by ___ inch sheathing (diagonal or straight) and composition roofing material. ________ was utilized prior to 1933, and ________ was utilized after 1933.
metal tie rods
2x6
1x6
straight sheathing
diagonal sheathing
BRIDGE TRUSS ROOF
_______(installed over existing) is utilized, if modified for the Earthquake Ordinance.
plywood decking
BRIDGE TRUSS ROOF
Hazards
The trusses are in tension and compression and may fail under severe fire conditions.
Similar to the bridge truss roof. This popular type of roof was constructed during the 1930’s, 1940’s, and 1950’s on both small and large commercial type structures.
BOWSTRING ARCH ROOFS
BOWSTRING ARCH ROOFS
Usually a large size (2 x 12 or 2 x 14 inch) of lumber comprises the arch trusses and related members.
Usually a large size (____ or ____ inch) of lumber comprises the arch trusses and related members.
2x12 or 2x14
BOWSTRING ARCH ROOFS
Some arch trusses have multiple beams forming one truss arch. Rafters are _____ inches or larger and covered by ____ inch sheathing (diagonal or straight) and composition roofing material.
2 x 6
1 x 6
An egg crate, geometric or diamond-patterned roof.
LAMELLA ARCH ROOF
LAMELLA ARCH ROOF
Constructed from _____ inch wood framing with steel plates and bolts at junctions of framing. Roof decking is _____ inch sheathing and composition roofing material.
2 x 12
1 x 6
LAMELLA ARCH ROOF
This type of an arch roof is supported by exterior _______ or internal tie rods with ________, and is common on gymnasiums, large buildings used for recreational activities, large supermarkets, etc.
buttresses
turnbuckles
LAMELLA ARCH ROOF
Hazards
Although these roofs offer some protection when exposed to fire, total roof collapse may occur if fire removes more than __% of the roof structure. Total roof collapse of the roof can result from “the ____ ____”
20%
domino effect
Although this roof is similar in appearance to bowstring arch and lamella roofs, it is significantly different in that it is an arched roof that uses metal tie rods to offer lateral support for the walls of the building.
TIED TRUSS ARCH ROOFS
TIED TRUSS ARCH ROOFS
Tie rods (usually ___ inch in diameter) with turnbuckles are used below each arch member to ensure the arches do not push the exterior walls ______. Tie rods may pass through exterior walls outside plates, which facilitate identification of this style of roof. Proper tie rod tension is maintained by _____.
5/8’’
outward
turnbuckles
TIED TRUSS ARCH ROOFS
Top chords of arch member may utilize laminated ______’s or large members. Rafters are _____ inches or larger and covered by _____ inch sheathing (diagonal or straight) and composition roofing material.
2 x 12s
2 x 10
1 x 6
TIED TRUSS ARCH ROOFS
Hazards
The primary hazard of this roof is early failure of the _________ and _______.
metal tie rods and turnbuckles
Used on commercial buildings to yield additional light and ventilation for manufacturing type occupancies.
SAWTOOTH ROOF
SAWTOOTH ROOF
It is constructed with rafters of ______ inches or larger and utilizes wood and/or metal supports for bracing. The sloping portion is covered with _____ inch sheathing (or ½ inch plywood in newer roofs) and composition roofing material.
2 x8
1 x6
Sawtooth roof
Strength
Additionally, this type of roof is easy to ventilate; utilize the hinged _______.
Panes of glass
Conventional flat roof
Wood rafters of various sizes (___ inches and larger) are laid across outside walls, or outside wall to interior walls/structural supports. Rafters are covered with _____ inch sheathing or plywood (in newer applications) and composition roofing material.
2 x 6
1x6
Conventional flat roof
Strengths
Susceptibility to fire is totally dependent on the size of the rafters, their “______” spacing and the type of decking that has been utilized. Consider the ______ of the building a strong point.
On-center
Perimeter
consists of top and bottom parallel wooden chords that are connected by a wooden stem.
Wooden I beam