Book 29 Building Construction Flashcards
Knowledge of building construction allows the evaluation of
-structural integrity: remaining time
-ladder placement: strong areas
-forcible entry/search and rescue: best entry and floor plan
-ventilation feasibility: safe routes of travel and structural member direction
sizeup consists of 3 operations
-analyze the situation
-decide on a plan (strategy)
-put the plan into operation (tactics)
structure fire sizeup of building type and construction will indicate
-rate of burning
-possible avenues of fire spread
-problems to confine fire
-structural integrity
-time to conduct safe fireground operations
building sizeup
-construction styles
-roof styles
-construction methods
-age of the building
construction styles
-CONVENTIONAL:
structural members depend on size for strength; minimum 2x4
-LIGHTWEIGHT:
structural members depend on total sum of other members for strength; 2x3 or 2x4 standard
a single lightweight truss structural member can span…
70 feet
structure can be considered structurally strong is dependent on
-type of construction
-how long has the fire been burning
-fire intensity
roof styles
gable
hip
flat
bridge truss
arch (bowstring, lamella, tied truss)
sawtooth
conventional gable roof
-ridge board: 1x6
-rafters: 2x6 spaced 16”-24” on center
(36” on center for steep pitched)
-additional support by collar beams and ceiling joists
-1x4 or 1x6 sheathing
Lightweight construction (gable, hip)
-utilizes 2x3 or 2x4 wood trusses held together by metal gusset plate
-24” on center truss rafters
-metal gusset plates: 18 gauge steel, 3/8” penetration
-3/8” or 1/2” plywood decking
-trusses share common features top chords, bottom chords, and webbing
-bottom chord replaced ceiling joist found in conventional construction
-strong areas are ridge and outside walls
-early failure rate and collapse due to metal gusset plat and small member trusses
Interior partition walls in lightweight
-may not support truss along bottom chord
-18 gauge roof truss clips found nailed to bottom chord (every 3-5 trusses) and top plate of interior walls
-clips provide some stability for interior partition walls
-interior partition walls could be classified as free standing
conventional hip roof
-ridge board: 2x6
-rafters: 2x6 16”-24” on center
-ends of roof terminate in hip configuration
-valley rafters utilized where 2 roof lines join together
-strong areas are ridge, valley rafters, hip rafters and outside walls
Bridge truss roof
-1930’s and 1940’s
-2x6 rafters
-2x12 truss members
-metal tie rods may be used vertically for additional support
-1x6 sheathing (diagonal or straight)
plywood decking installed over existing if modified for earthquake ordinance
-underside of roof common to interior space or modified for storage in attic
-bottom chords can be covered with sheathing to hide
- early collapse not a primary concern; fails in sections
bow string arch roof
-1930’s 1940’s and 1950’s small and large commercial
-2x12 or 2x14 truss members
-rafters: 2x6
-1x6 sheathing (diagonal or straight)
plywood decking installed over existing if modified for earthquake ordinance
-underside of roof common to interior space or modified for storage in attic
-bottom chords can be covered with sheathing to hide
- early collapse not a primary concern; fails in sections
lamella arch roof
-egg crate, geometric or diamond patterned
-2x12 w/ steel plates and bolts at junctions of framing
-1x6 sheathing
-supported by exterior buttresses or internal tie rods w/ turnbuckles
-gymnasiums, large buildings used for recreation, large supermarkets
-total roof collapse if fire removes more than 20% of roof; or
can result from “domino effect”
