Construction/Building Features Flashcards
Most common taxpayer size?
100’x100’
-cheap flimsy construction with little or no fire retarding
Turn of century-1920’s
- usually 1 story in height
- may be considered wood frame (with masonry exteriors)
- original ceilings may be TIN
- lath, plaster, wood, covered with Tin
- decorative METAL CORNICE, CAN PROVIDE COCKLOFT ACCESS
Most prevalent- 1920’s-1960’s
- larger in area
- firewalls may have been installed
- many are 2 stories
- 2nd floor-dancehalls, restaurants, factories,etc.
- cornices are facade type-NO COCKLOFT ACCESS
Newer..1960’s-present
- use of COMBUSTIBLE CONSTRUCTION REDUCED
- steel bar joists (floor/roof) instead of wood beams-lighter weight
- concrete poured floor on metal decking-metal joists support
- poured pitch and grave covering
Mezzanie?
- most cases used for STORAGE OF GOOD, can contain offices and sales areas
- height of ceilings will be BELOW AVERAGE
- access/small wooden stairs
- majority UNENCLOSED
1938 Code?
Area exceeding 10,000 sq feet
1968 Code?
Area exceeding 7,500 sq feet
2008-Mercantile Code
Full Building-area exceeds 12,000 ft. OR combined area on all floors (including mezz) exceeds 24,000 sq ft.
-storage of merchandise high piled racks or rack storage arrays
OCCUPANY within buildings-area exceeding 7,500 sq ft. OR AREA of any size is located 3 stories above grade or area of any size contains an unenclosed stair or escalator connecting 2 or more floors
Cockloft ?
4 inches to 6 feet
Most common taxpayer roof?
wood joists covered with either tongue and groove boards or plywood-then covered with combustible waterproofing/tar paper
- roof joists supported at 20 ft intervals
- sometimes inverted roof is constructed over an existing roof and forms an ADDITIONAL COCKLOFT
Truss?
- greater spans while minimizing the increase in the size of the spanning members
- top chord/bottom chord-connected by WEBS
- either wood or steel
- open web joist or steel bar joist is a light weight parallel chord truss
Wooden Bow String Truss?
-HUMP LIKE ROOF PROFILE
-longer the span/HIGHER THE BOW
-easily recognized
bow string truss roof may only SUPPORT 40 % of the load they were originally designed to hold
-snow loads can affect Truss (eccentric load)-OF CENTER
-truss failure can occur WITHOUT FIRE IMPINGEMENT
-failure of one truss can lead to failure of entire truss
-older truss roof-may be spaced 10-20 ft apart
-fail WITHOUT WARNING
-steel stretches/wood snaps
Buildings with Bowstring Truss Roof ?
MUST be entered into CIDS
BWSTRG
Open Web Steel Joists?
- modern taxpayers
- NO fire resistance rating (DEPENDS ON CEILING FINISH)
- span distances up to 60 feet
- may be covered with gypsum concrete- 2” thick
- UNPROTECTED OPEN WEB STELL JOIST may collapse after 5 to 10 minutes
Signs?
smaller signs attached to the front wall over stores sometimes cover openings into the cockloft and can be removed for early stream operation into the cockloft
Stone or block?
may SPALL due to heat or subsequent stream application
Stability of Masonry Walls?
dependent on integrity of the ROOF-monolithic brace which ties walls together
- collapse of roof-LATERAL LOAD-may either push out or pull in on the walls
- Concrete blocks will HINGE AT GROUND LEVEL-and entire side or wall will fall intact
- Brick walls CRUMBLE/BREAK as they fall-large sections can project good distance
Parapet Wall Collapse?
FRONT WALL/ANY PARAPET WALL FACING THE STREET
- I Beams heated may expand and push out parapet walls
- often UNSUPPORTED LATERALLY FOR A LONG DISTANCE , receiving support only at ends where they are tie into crosswalls
-long section of parapet wall remains intact as it collapses
Canopy/Marquees?
- fire in cockloft can weaken these attachments/causing them to collapse
- MARQUEES are hollow boxes that can fill with water- 12’x24’ marquee, 4 ft deep- 35 tons of water/hanging swimming pool
“I” Beams?
- exposed steel is common in taxpayers
- absorb heat
- 50 ft. long steel beam, heat over 970 F, will extend- 4 inches
- temp. increases/so does expansion rate
- 1000 F/ 100 ft beam will extend 9.5 inches
- these extended beams will push out exterior walls
- steel beams cooled by hose will REGAIN its strength and load carrying ability (cast iron will not)
when these steel beams are heated from 1000 to 1500 F, they soften and fail, this temperature can be reached in 5 to 10 minutes at a fire….only matter of time at an UNCONTROLLED FIRE (30 MINUTES for small beam sections ) until these beams are heated beyond their strength limitations
Cast Iron Columns fail in..?
30 minutes
-column failure more serious than girder or beam
steel cooled regains strength
CAST IRON will NOT