Building Construction Understanding Construction Part Two Tom ...

clanmurderUrban and Civil

Nov 15, 2013 (3 years and 8 months ago)

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In New York State, building construction, heating
plants, HVAC, etc., are regulated by the following;



The Building Code



The Existing Building Code



The Fire Code



The Fuel and Gas Code



The Mechanical Code



The Plumbing Code



The Residential Code



The Energy Conservation Code

Codes



also Reference Standards (NFPA, ANSI, ASME, etc..)



Additionally, we also have to comply with;



NYS approved “more restrictive” local codes (i.e.,
county, town, city, village)



These codes provide minimum requirements.



As with all codes, there are exceptions, such as, the
NYS Building Code does
not

apply to detached one
-
and
two
-
family dwellings and multiple single
-
family dwelling
(townhouses) not more than three stories in height with
separate means of egress. These buildings fall under the
Residential Code of New York State
.



To alert you to potential construction hazards,




To enable a safe and effective fire attack,




By knowing basic building construction types, we
can approximate how fire will spread and allow us
to extinguish it quickly,




“The building is your enemy… know your enemy”
Francis L. Brannigan.



There are TWO basic types of construction: “It either
burns (combustible) or it does not burn
(noncombustible)”




All buildings in the US are constructed by one of the
five

construction categories;



Type “1”
-

Fire Resistive


Least

Combustible



Type “2”
-

Non
-
Combustible



Type “3”
-

Ordinary



Type “4”
-

Heavy Timber



Type “5”
-

Wood Frame


Most

Combustible



Four

of the five types have subgroups “A” & “B”.



Means Protected
;



all structural members have an additional fire
rated coating or cover by means of sheetrock,
spray on, or other approved method,



the additional fire rated coating or cover
extends the fire resistance of the structural
members by at least 1 hour.



Means Unprotected;



all structural members
have no

additional fire
rated coating or cover,



exposed members are only fire resistant
according to their natural ability, characteristics,
and fire rating.

STRUCTURAL CHARACTERISTICS AND
HAZARDS

Type “3”
-

(A)
(protected)



Ordinary

(ISO Class 2)

(#211, NFPA 5000 “Building & Safety Code”)




structural frame, columns, etc.
-

1 hour rating



exterior bearing walls


2 hour rated



interior bearing walls


1 hour rated



floor construction, beams and joists


1 hour rated



roof construction, beams and joists


1 hour rated

2010 New York State Building Code


Type “3”
-

(B)
(unprotected)



Ordinary

(ISO Class 2)

(#200, NFPA 5000 “Building & Safety Code”)




structural frame, columns, etc.
-

0 hour rating



exterior bearing walls


2 hour rated



interior bearing walls


0 hour rated



floor construction, beams and joists


0 hour rated



roof construction, beams and joists


0 hour rated

2010 New York State Building Code




predominate and common construction type,



also know as “brick and joist” structure, (common
terms “Main Street, USA” or “Downtown, USA” and
“Taxpayer”



exterior load bearing walls are of masonry and
some or all other structural components are
combustible (wood),



masonry walls can be brick, stone, or concrete
block and terra cotta block in some older buildings,



interior structural members almost all wood,



wood used has smaller dimensions than Type “IV”.

TYPE “3”
-

Ordinary



Characteristics;



normally used for larger, sometimes multi
-
story,
commercial or multi
-
family structures,



has also been used for one and two family
buildings,



if floor and roof construction and their supports
and all openings through floors (stairwells) are
enclosed with one
-
hour fire resistive materials, the
construction is classified as “Protected”,



generally built no higher than 6 to 8 stories, most
are 2 to 4 stories high,



typically wall thickness range from 6” to 30”,

Type 3 Construction



rarely protected by a sprinkler system,



many have been remodeled and altered,



roof often similar to floor construction,



hazards reduced by using fire
-
stops,



unstable under fire conditions,



highly damageable buildings,



primary fire hazard
-

fire and smoke spread through
concealed spaces,



fire load


construction materials and contents,


TYPE “3”
-

Ordinary



typically will have two load
-
bearing walls (long
walls) and two curtain walls (short walls).

Type 3 Construction


Residential Type “3” building

One &
Two
Family

Type “3” Multiple Residence

Type “3” Commercial and Residential

Two story commercial Type “3” building

TYPE “3”
-

Ordinary



Type “3” buildings have been constructed in
two

distinct types;



Older


late 19
th

and early 20
th

century and,



Newer.




“Older”

buildings;



tongue and grove floor boards,



solid lumber joists and rafters ( can be 3” x 10”),



columns could be added for additional support



room size limited by span of supporting element,

TYPE “3”
-

Ordinary



floor joists commonly have a “fire cut” on each
end to keep floor joists from pushing the wall
down,








1” to 1 ½” wooden planks commonly used in
the roof assembly.

TYPE “3”
-

Ordinary



“Newer”

buildings;



flooring may consist of plywood, oriented
strand board (OSB),



laminated veneer lumber (LVL), and parallel
strand lumber (PSL), supported by



lightweight wooden trusses, and wooden I
-

beams,



these supports are more likely to collapse
sooner than larger solid lumber joists,



roof construction using lightweight materials.



Stability of masonry walls,



Stability of interior column, girder and beam
system,



Void spaces,



Excessive fire loads, “dead” loads
(HVAC, Solar Arrays)



Bow string truss roof,



Alterations can have an effect on the building,



The largest concealed space is the “Cockloft”, an
open space for fire and smoke spread,



Braced Wall Spreaders
-

danger


wall can be out
of alignment.

Solar Arrays and
HVAC Units

Braced
Walls

A basic sign that a wall is in distress

Braces of unprotected steel or cable will fail at fire
temperatures

Arrows mark locations where star
-
shaped anchor plates were
located on the west
-
side of the theater building that was
adjacent to the fire building. The anchor plates appear to have
been attached to the ends of the heavy timber roof trusses
supporting the roof and also to some of the second
-
floor joists.
NIOSH F2011
-
15

Photo shows star
-
shaped anchor plates located on the D
-
side wall in the area that collapsed.
NIOSH F2011
-
15

Photo shows star
-
shaped anchor
plate attached to end of floor joist.

Photo shows star
-
shaped
anchor plate attached to end
of heavy timber roof truss.

Type “3” Bowstring truss
roof

Collapse scene as viewed from building rear
facing building front. Note portion of bowstring
truss leaning against wall at right side of photo.

(Photo courtesy of fire department)

NIOSH F2010
-
38

Photo shows the wall that supported western end of the bowstring truss roof.
The two arrows indicate the truss
-
end pockets in the brick masonry wall at
the top of the brick pilasters where the ends of the two bowstring trusses
rested. The roof was supported in the middle by the two bowstring trusses
while the north and south ends were supported by the front and rear non
-
load
bearing walls. The line indicates the approximate curvature of the roof.
(NIOSH
photo F2010
-
38)

NIOSH F2009
-
21 Photo


STRUCTURAL CHARACTERISTICS
AND HAZARDS

Type “4”
-

Heavy Timber

(ISO Class 2)

(#2HH, NFPA 5000 “Building & Safety Code”)




structural frame, columns, etc.


heavy timber



exterior bearing walls


1 hour heavy timber



interior bearing walls


2 hour rated



floor construction, beams and joists


heavy timber



roof construction, beams and joists


heavy timber

2010 New York State Building Code




Characteristics;



heavy timber construction is one of the oldest
types of buildings used in this country,



heavy timber buildings were originally designed
and used as multi
-
story industrial or storage
occupancies,



fire resistance is attained by placing limitations
of minimum sizes on wood structural members
and minimum thickness and composition of wood
floors and roofs,



will have four bearing exterior walls,


construction includes
columns

not less than 8”
thick in any dimension,



beams and girders not less than 6” x 10”,



roof framing

is not less than 6” wide x 8” depth,



floors and roofs have thicker than normal
construction consisting of varying layers of
materials that build up to a deck of 3” thick to 4”
wide,



arches and trusses not less than 8” thick in any
dimension.



usage of approved fastenings and adhesives,



lumber may be sawn or laminated,



usually found in very old mills, factories, and
warehouse, and in older churches,



exterior walls are noncombustible,



interior structures made of solid or laminated
wood with no concealed spaces,



does not have plaster walls & ceilings covering
interior framework,

TYPE “4”
-

Heavy Timber



wood has large dimensions, much heavier, more
difficult to ignite, can withstand fire for longer time
frames,



primary fire hazard
-

combustible contents of
structural members,



does not fail early in a fire,



because of massive amount of combustible
materials there will be serious heat given off and may
pose exposure protection problems,

TYPE “4”
-

Heavy Timber

Heavy Timber Frame building

Heavy Timber
columns, beams
& girders

Masonry walls

Large open spaces, lack of
hidden voids



Heavy fire loading,



Combustible finishes and furnishings,



Wooden floors/ceilings and coverings,



Large open spaces,



Unprotected openings



Heavy content loading;



combustibles stored in high piles next to each
other,



usually found in commercial and storage facilities,



this may override sprinkler system and provide
access problems,



proper inspection and enforcement effective in
these types of facilities.



Combustible furnishings/finishes;



contribute to fire spread and smoke production.




Wooden floors and ceilings;



contribute to fire loading,



prolonged exposure may result in collapse,




Large open spaces;



contributes to spread,



warehouses, churches, large atriums, common
attics, and theaters.



Unprotected openings;



floor openings for stairwells, freight elevators or
conveyor devices




SIZEUP


read a building to identify important
factors;



class of building construction,



resistance to fire, heat to critical structural
members,



renovations that may have created void areas,



movement of heat, smoke and fire within the
building,

Summary



areas around utility services should be suspected
as areas where fire can spread,



many older buildings have new plumbing and
electrical systems installed,



knowledge of potential building concerns can be
attained by performing inspections during new
construction or in existing buildings,



Lastly, information my be available through your
local fire inspector and/or building department.

Summary


Prepared by Thomas Bartsch

Chief Fire Inspector (ret)


11/16/2013