A.
For the purposes of this code, all structures shall
be classified with respect to occupancy as follows:
(1)
Public buildings. Public buildings are structures
or parts of structures in which persons congregate for civic, political,
educational, religious, social or recreational purposes, including,
among others, courthouses, schools, colleges, libraries, museums,
exhibition buildings, lecture halls, churches, assembly halls, lodge
rooms, dance halls, theaters, bathhouses, armories and passenger depots.
(2)
Institutional buildings. Institutional buildings are
structures or parts of structures in which persons are harbored to
receive medical, charitable or other care or treatment or in which
persons are held or detained by reason of public or civic duty or
for correctional purposes, including, among others, hospitals, asylums,
sanitoriums, firehouses, police stations and jails.
(3)
Commercial buildings. Commercial buildings are structures
or parts of structures which are not public buildings, institutional
buildings or residence buildings, including, among others, office
buildings, mercantile buildings, warehouses, freight depots, car barns,
stables, factories, laboratories, smokehouses grain elevators, coal
pockets, central station power plants, electric substations, garages,
motor vehicle repair shops and gasoline vending stations.
(a)
Mercantile building defined. A mercantile building
is a place in which one or more persons are employed, in which goods,
wares or merchandise are offered for sale and includes a building,
shed or structure or any part thereof occupied in connection with
such an establishment. Mercantile buildings include, among others,
salesrooms, stores, markets and restaurants.
(4)
Residence buildings. Residence buildings are structures
or parts of structures in which sleeping accommodations are provided,
except such as may for other reasons be classed as public buildings,
including, among others, dwellings, multiple dwellings, hotels, lodging
houses, dormitories, convents, studios and clubhouses having sleeping
accommodations.
(a)
Multiple dwelling defined. A multiple dwelling
which is either rented, leased, let or hired out to be occupied or
is occupied as the abode, residence or home of three or more families
living independently of each other. For the purpose of this code,
multiple dwellings are divided into two classes, Class A and Class
B.
(b)
Class A multiple dwelling defined. A Class A
multiple dwelling is a multiple dwelling which is occupied, as a rule,
for residence purposes and not transiently. This class shall be deemed
to include tenement houses, flat houses, maisonette apartments, apartment
hotels, apartment houses, bachelor apartments, studio apartments,
duplex apartments, kitchenette apartments and all other multiple dwellings,
except Class B multiple dwellings, whether or not such other multiple
dwellings are specifically designated by name.
(c)
Class B multiple dwelling defined. A Class B
multiple dwelling is a multiple dwelling which is occupied, as a rule,
transiently as the more or less temporary abode of individuals or
families who are lodged with or without meals. This class shall be
deemed to include hotels, lodging houses, rooming houses, boardinghouses,
boarding schools, furnished room houses, lodgings, clubhouses, college
and school dormitories.
(5)
Doubtful classification. In case any building is not
specifically provided for or where there is any uncertainty as to
its classification, its status shall be determined by the Superintendent
of Buildings.
(6)
Mixed occupancy. In case a building is occupied or
used for different purposes in different parts, the provisions of
this code applying to each class of occupancy shall apply to such
parts of the building as come within that class, and if there should
be conflicting provisions, the requirements securing the greater safety
shall apply.
Structures shall be classified according to
the type of construction as:
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Class 1 Fireproof Structures
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Class 2 Fire-Protected Structures
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Class 3 Nonfireproof Structures
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Class 4 Wood Frame Structures
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Class 5 Metal Structures
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Class 6 Heavy Timber Structures
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Class 7 Air-Supported Structures
[Added 10-27-1980 by L.L. No. 10-1980] | |
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The exterior walls of all Class 1, Class 2 and Class 3 structures shall be as provided in § 86-60, Masonry construction.
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A.
Class 1 Fireproof Structures.
(1)
Class 1 Fireproof Structures are those in which the
walls and the structural members are made of incombustible materials
or of assemblies with the following minimum fire-resistive ratings:
(a)
Four hours for exterior walls, fire walls, party
walls, piers, columns and interior structural members which carry
walls.
(b)
Three hours for other girders; fire partitions;
floors, including their beams and girders; beams; roofs and floor
fillings; and required stairway enclosures.
(c)
One hour for permanent interior partitions.
B.
Class 2 Fire-Protected Structures.
(1)
Class 2 Fire-Protected Structures are those in which
the walls and structural members are made of incombustible materials
or of assemblies with the following minimum fire-resistive ratings:
(a)
Three hours for exterior walls and shafts, except as otherwise provided in § 86-73I Dumbwaiter shafts, and required stairway enclosures in structures more than 50 feet in height and the floor above the cellar or basement in residence structures.
(b)
Structural members in exterior walls, those
which support walls, shafts and interior columns in public institutional
and commercial buildings, are protected by materials having a fire-resistive
rating of at least three hours or assemblies having a fire-resistive
rating of at least three hours.
(c)
Two hours for shaft enclosures, except as otherwise provided in § 86-73I, Dumbwaiter shafts, and required stairway enclosures in structures 50 feet or less in height.
(d)
Interior columns in residence structures are
protected by materials having a fire-resistive rating of at least
two hours.
(e)
One and one-half hours for all floors, other
than the first floor of residence structures, and roofs.
(f)
One hour for all other walls and partitions.
C.
Class 3 Nonfireproof Structures.
(1)
Class 3 Nonfireproof Structures are those in which
the exterior walls are of masonry or reinforced concrete with a fire-resistive
rating of at least three hours and the interior framing is partly
or wholly of wood or unprotected iron or steel. The floor above the
cellar or basement and the columns below such floors are constructed
of incombustible materials or of assemblies having a fire-resistive
rating of three hours, except in residence buildings of three stories
and a basement or less in height and in other structures not over
four stories or 40 feet in height. Shafts and required stairway enclosures
are made of incombustible materials or assemblies having a fire-resistive
rating of at least two hours, except that in residence buildings of
three stories and a basement or less in height and in other structures
not over four stories or 40 feet in height, such shafts and required
stairway enclosures may be made of incombustible materials or assemblies
having a fire-resistive rating of at least one hour.
D.
Class 4 Wood Frame Structures. Class 4 Wood Frame
Structures are those in which the structural parts and materials are
of wood or other combustible materials or are dependent upon a wood
frame for support, including construction having an incombustible
veneer or an incombustible covering such as corrugated iron or corrugated
asbestos cement composition sheets, except that all columns, footings
or other supports of the first floor framing shall be of incombustible
materials.
E.
Class 5 Metal Structures. Class 5 Metal Structures
are those in which the structural frame work is of metal and in which
the walls and roofs are of metal, flat or corrugated cement asbestos
composition sheets or of incombustible material other than masonry
and which are without fireresistive protection or without sufficient
protection to withstand the fire tests required for other classes
of structures.
F.
Class 6 Heavy Timber Structures. Class 6 Heavy Timber
Structures are those in which the exterior walls are of masonry or
reinforced concrete with a fire-resistive rating of at least three
hours and the interior framing above grade floor is of wood structural
members having no beam or girder less than six inches in the least
dimension and not less than 10 inches in depth and wood posts or columns
not less than eight inches in any dimension and floors of splined
or tongue and grooved plank shall be not less than three inches in
thickness and covered with one-inch flooring laid crosswise or diagonal
or floors of planks shall be at least four inches thick, set on edge
close together with broken joints and spiked at intervals of not more
than 18 inches.
(1)
Shafts and required stairways shall be enclosed in
materials or assemblies having a fire-resistive rating of at least
two hours.
(2)
Wherever structural steel is used it shall be protected
as prescribed for similar uses under Class 2 Fire-Protected Structures.
(3)
The construction of the floor immediately over the
basement or cellar and all floor construction below it, including
columns, shall be as prescribed under Class 2 Fire-Protected Structures.
(4)
Wooden structural members supported by masonry or
reinforced concrete walls shall have at least eight inches of masonry
between the end of the member and the outer face of the wall or, in
the case of two wood structural members from opposite sides, at least
eight inches of masonry between the ends of the beams.
(5)
Roofs shall be the same as floors, except that planks
shall be at least 2 1/2 inches thick, and beams supporting the
roof shall be at least six inches in smallest dimension.
G.
Mixed Construction. No building or portion thereof
shall be required to conform to the details of a type of construction
higher than that type which meets with the requirements of this code
based upon occupancy, size and location even though portions of the
construction materials or assemblies in the building conform to a
higher type of construction.
H.
Class 7 Air-Supported Structures. A structural and mechanical system which is constructed of high-strength fabric or film and achieves its shape, stability and support by pretensioning with internal air pressure. Construction shall be in accordance with Article XVIII, Air-Supported Structures.
[Added 10-27-1980 by L.L. No. 10-1980]
