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<br />6. Enclosures of interior stairwl.
<br />(a). All interior stairways in buildings connecting two or
<br />more stories, whether required as exits or not, shall be enclosed,
<br />except as otherwise provided in paragraph (d).
<br />(b). In unsprinklered buildings which exceed 30 feet to the
<br />floor of the topmost story, or are occupied by more than 75 persons
<br />above, or 40 persons below, the first story above grade, not counting
<br />those in the first story, and in multifamily houses 4 stories or more
<br />in height, interior required stairways shall be enclosed with fire
<br />partitions.
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<br />WORKMANSHIP AND MATERIALS.
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<br />Workmanship
<br />ma terials shall
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<br />SECTION 21
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<br />All building materials shall be of good quality.
<br />in the fabrication, preparation and installation of
<br />conform to generally accepted good practice.
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<br />DESIGN LOADS, STRESSES AND WIND
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<br />SECTION 22.
<br />PRESSURE.
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<br />(c). In other buildings interior stairways shall be enclosed in
<br />partitions having a fire resistance rating of not less than one hour.
<br />In buildings of fireproof construction and semifireproof construc-
<br />tion such partitions shall be noncombustible.
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<br />An enclosure shall not be required for
<br />(1). A flight of stairs from the main entrance floor to the
<br />next above when such stairs are not a part of a required
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<br />(d)
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<br />Buildings or structures, including tanks, towers and signs, here-
<br />after erected and all new construction in the alteration of heretofore
<br />erected buildings or structures shall be designed and constructed for
<br />live and dead loads and wind pressures in accordance with the Na-
<br />tional Building Code, 1949 Edition, recommended by the National
<br />Board of Fire Underwriters, and with resulting' stresses not in ex-
<br />cess of those permitted by said code.
<br />
<br />mezzanine having
<br />the floor immedi-
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<br />floor
<br />sooinvay.
<br />(2). A flight of stairs in a building of fireproof construc-
<br />tion,' semifireproof construction, or a sprinklered building of
<br />heavy timber construction or ordinary construction or non-
<br />combustible construction, when such stairs connect only one
<br />story with one other story immediately above or below it. In
<br />such case the upper end of the stairway shall not connect to a
<br />hallway serving as an exit except through a fire door.
<br />(3). A flight of stairs from a balcony or
<br />an area not exceeding 25 per cent of that of
<br />ately below.
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<br />FOUNDATIONS.
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<br />Except when erected upon hardpan or solid rock or upon walls
<br />or piers on the water front, foungation walls or other permanent
<br />supports shall be carried not less than one foot below frost line
<br />and shall rest on solid ground or on leveled rock, or on piles or
<br />ranging timbers when solid earth or rock is not found; provided
<br />that wherf one-story buildings of wood frame construction, ordinary
<br />construction, noncombustible construction or unprotected metal
<br />construction do not exceed 750 square feet in area, such foundation
<br />walls or other permanent supports shall not be required.
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<br />23.
<br />
<br />SECTION
<br />
<br />1. Construction.
<br />(a). All masonry shall be protected against freezing for at
<br />least 48 hours after being placed. Unless adequate precautions
<br />against freezing are taken, no masonry shall be built when the
<br />temperature is below 320 Fahrenheit on a rising temperature or
<br />below 400 on a falling temperature, at the point where the work is
<br />in progress. No frozen materials shall be built upon.
<br />(b). Except when carried independently by girders at each
<br />floor, no wall shall be built up more than 25 feet in height in advance
<br />of other walls of the building.
<br />(c). Masonry walls that meet or intersect shall be adequately
<br />bonded or anchored. Piers having less than 4 square feet of cross-
<br />sectional area when located at an intersection with a wall shall be
<br />bonded into and built as part of that wall.
<br />(d). Except for window-paneled backs and permissible chases
<br />and recesses, walls shall not vary in thickness between their lateral
<br />supports. When a change in thickness, due to minimum thickness
<br />requirements, occurs between floor levels, the greater thickness shall
<br />be carried up to the higher floor level.
<br />(e). Isolated piers or posts on the interior of buildings shall
<br />not be built of stone. The unsupported height of piers shall not
<br />exceed 10 times their least dimension. Hollow masonry units shall
<br />not be used for isolated piers to support beams and girders unless
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<br />22
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<br />(e). Openings. No openings except the necessary doorways,
<br />and windows opening to the exterior of the building, shall be per-
<br />mitted in a stair enclosure required by this section. Such doorways
<br />shall be equipped with approved self-closing. fire doors, except that
<br />when fire partitions are not required for the enclosure, substantial
<br />self-closing metal or metal covered doors or solid wooden doors of
<br />the flush type of nominal thickness not less than 1% inches may be
<br />used. In school buildings, doors on openings in stair enclosures
<br />may have wired glass panels; the area of such glass in anyone
<br />door shall not exceed 720 square inches.
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<br />MASONRY.
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<br />24.
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<br />SECTION
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<br />7. Width of interior stairways. The minimum unobstructed
<br />width of a stairway serving as a required exit shall be not less than
<br />44 inches; provided that in multifamily houses and storage buildings,
<br />and in other buildings occupied by a single tenant and limited in
<br />occupancy to 40 persons, such width may be 36 inches. The width
<br />of stairs shall be measured between hand rails except where hand
<br />rails project not more than 30 inches into such width.
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<br />8. Treads and risers.
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<br />(a). Treads and risers of required stairs shall be so propor-
<br />tioned that the product of the width of tread, exclusive of nosing,
<br />and the height of riser, in i~ches, shall be not less than 70 nor more
<br />than 75; but risers shall not exceed 7;14 inches in Aeight, and treads,
<br />exclusive of nosing, shall be not less than 90 inches wide; except
<br />that in schools the proportion and dimensions of the treads and
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