Section 27-269
§ 27-269 Construction classes. Table 3-3 lists construction classes
that shall be established for classifying buildings and spaces by
construction in accordance with the provisions of articles fifteen,
sixteen and seventeen of this subchapter.
Table 3-3 Construction Classes
Construction Group Class
I--Noncombustible I--A--(4-hr. protected)
I--B--(3-hr. protected)
I--C--(2-hr. protected)
I--D--(1-hr. protected)
I--E--(unprotected)
II--Combustible II--A--(heavy timber)
II--B--(protected wood joist)
II--C--(unprotected wood joist)
II--D--(protected wood frame)
II--E--(unprotected wood frame)
Section 27-270
§ 27-270 Classification of buildings and spaces. Every building, room,
or space hereafter altered or erected shall, for the purposes of this
code be classified in one of the construction classes listed in table
3-3.
Section 27-271
§ 27-271 Classification table. The fire-resistance ratings of
construction elements in hours listed in table 3-4 shall be used as a
basis for classifying buildings and spaces by construction.
Fire-resistance ratings shall be based on the test procedures of
reference standard RS3-1 and shall apply to all occupancy groups except
as specifically noted. For hazardous occupancies involving an
exceptionally high degree of fire risk or an exceptionally high
concentration of combustible or flammable contents, the commissioner may
increase the requirements of table 3-4.
(For Table 3-4 see chapter 839 of the laws of 1986)
Notes:
a. The area of openings permitted in exterior walls at any story shall
be obtained by multiplying the percentage shown in the table by the
exterior separation distance in feet, and then multiplying that product
by the square-foot area of the facade of that story. Requirements for
protected exterior openings shall not apply to churches or to buildings
classified in occupancy groups J-2 and J-3. See section 27-331 of
article four of subchapter five of this chapter for additional
requirements for exterior walls and exterior wall openings.
b. Upon special application, the commissioner may permit exterior wall
openings to be constructed in excess of the permitted area established
by table 3-4 if such openings at the time of their construction are
located at least sixty feet in a direct line from any neighboring
building except as otherwise permitted by footnote f. Such additional
openings may not, however, be credited toward meeting any of the
mandatory natural light or ventilation requirements of subchapter twelve
of chapter one of this title. If any neighboring building is later
altered or constructed to come within the above distance limitation, the
affected exterior openings shall immediately be closed with construction
meeting the fire-resistance rating requirements for exterior wall
construction of the building in which they are located.
c. Applies to occupancy groups A, B-1, B-2, and D-1.
d. Applies to all occupancy groups other than those described in
footnote c.
e. See subdivision (i) of section 27-375 of article five of subchapter
six of this chapter for additional impact resistance requirements
applicable to certain stair enclosures and for certain exceptions to
stair enclosure requirements.
f. When two or more buildings are constructed on the same lot, and the
combined floor area of the buildings does not exceed the limits estab-
lished by tables 4-1 and 4-2 for any one of the buildings, no
fire-resistance rating shall be required for nonbearing portions of the
exterior walls of those buildings facing each other, and there shall be
no limitation on the permitted amount of exterior openings.
g. Fire retardant treated wood complying with the requirements of
section 27-328 of article three of subchapter five of this chapter may
be used.
h. Tabulated ratings apply to buildings over one story in height. In
one story buildings roof construction may be of material having 0 hour
fire-resistance rating.
i. Materials which are not noncombustible, as defined in subchapter
two of chapter one of this title, may be used in nonbearing construction
elements if they fall into one of the following categories:
1. Materials having a structural base of noncombustible material as
defined in subchapter two, and having a surface not over one-eighth inch
thick which when tested in accordance with the provisions of reference
standard RS 3-2 has a flame spread rating not higher than fifty.
2. Materials which when tested in accordance with the provisions of
reference standard RS 3-2 have a surface flame spread rating not higher
than twenty-five without evidence of continued progressive combustion,
and which are of such composition that surfaces which would be exposed
by cutting through the material in any way would not have a flame spread
rating higher than twenty-five without evidence of continued progressive
combustion.
j. Applies to the construction of the street floor and all
construction below the level of the street floor in buildings or spaces
classified in occupancy group J-2 except where the space below the
street floor does not exceed five feet in height.
k. Columns supporting the roof of a one-story building shall have the
same fire-resistance rating as required for a column supporting one
floor in a building of the same construction class.
l. Members supporting loads of not more than two floors or one floor
and a roof need not have a fire-resistance rating greater than the floor
construction fire-resistance requirement in buildings classified in
occupancy groups G, H, and J-2, not including unsprinklered spaces of
other occupancies, and in fully sprinklered buildings in occupancy
groups E and J-1.
m. See subdivision (c) of section 27-987 of article one of subchapter
eighteen of this chapter for additional impact resistance requirements
applicable to certain elevator enclosures.
Section 27-272
§ 27-272 False designation. No building or space shall be designated a
given construction class unless it conforms to the minimum requirements
for that class; and no building or space shall be posted, used,
designated, or advertised as of a given construction class unless it
complies with the minimum requirements of this code for that class.
Section 27-273
§ 27-273 Minimum requirements. When a class of construction is
utilized which is superior to that required for any particular use,
nothing in this code shall be construed to require full compliance with
the requirements for the higher class; the designated construction
classification of the building or space shall be that of the lesser
classification, unless all of the requirements for the higher class are
met.
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