Chapter 1 Administration

Chapter 2 Definitions

Chapter 3 Use and Occupancy Classification

Chapter 4 Special Detailed Requirements Based on Use and Occupancy

Chapter 5 General Building Heights and Areas; Separation of Occupancies

Chapter 6 Types of Construction

Chapter 7 Fire-Resistance-Rated Construction

Chapter 8 Interior Finishes

Chapter 9 Fire Protection Systems

Chapter 10 Means of Egress

Chapter 11 Accessibility

Chapter 12 Interior Environment

Chapter 13 Energy Efficiency

Chapter 14 Exterior Walls

Chapter 15 Roof Assemblies and Rooftop Structures

Chapter 16 Structural Design

Chapter 17 Structural Tests and Special Inspections

Chapter 18 Soils and Foundations

Chapter 19 Concrete

Chapter 20 Aluminum

Chapter 21 Masonry

Chapter 22 Steel

Chapter 23 Wood

Chapter 24 Glass and Glazing

Chapter 25 Gypsum Board and Plaster

Chapter 26 Plastic

Chapter 27 Electrical

Chapter 28 Mechanical Systems

Chapter 29 Plumbing Systems

Chapter 30 Elevators and Conveying Systems

Chapter 31 Special Construction

Chapter 32 Encroachments Into the Public Right-Of-Way

Chapter 33 Safeguards During Construction or Demolition

Chapter 34 Reserved

Chapter 35 Referenced Standards [PDF]

Appendix A Reserved

Appendix B Reserved

Appendix C Reserved

Appendix D Fire Districts

Appendix E Supplementary Accessibility Requirements

Appendix F Rodent Proofing

Appendix G Flood-Resistant Construction

Appendix H Outdoor Signs

Appendix I Reserved

Appendix J Reserved

Appendix L Reserved

Appendix K Modified Industry Standards for Elevators and Conveying Systems

Appendix M Supplementary Requirements for One- And Two-Family Dwellings

Appendix O Reserved

Appendix N Assistive Listening Systems Performance Standards

Appendix P R-2 Occupancy Toilet and Bathing Facilities Requirements

Appendix Q Modified National Standards for Automatic Sprinkler, Standpipe, and Fire Alarm Systems

Appendix R Acoustical Tile and Lay-In Panel Ceiling Suspension Systems

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The provisions of this chapter shall govern the design, materials, construction and quality of roof assemblies, and rooftop structures.
The following terms shall, for the purposes of this chapter and as used elsewhere in this code, have the meanings shown herein.
  BULKHEAD. An enclosed rooftop structure enclosing a shaft, stairway, tank or service equipment, or other space not designed or used for human occupancy.
  BUILT-UP ROOF COVERING. Two or more layers of felt cemented together and surfaced with a cap sheet, mineral aggregate, smooth coating or similar surfacing material.
  GREEN ROOF. A roofing assembly consisting of a roof covering and additional landscape material components, including growing media, filter fabric, drainage, and roof surface.
  INTERLAYMENT. A layer of felt or nonbituminous saturated felt not less than 18 inches (457 mm) wide, shingled between each course of a wood-shake roof covering.
  MECHANICAL EQUIPMENT SCREEN. A partially enclosed rooftop structure used to aesthetically conceal heating, ventilating and air conditioning (HVAC) electrical or mechanical equipment from view.
  METAL ROOF PANEL. An interlocking metal sheet having a minimum installed weather exposure of 3 square feet (.279 m2) per sheet.
  METAL ROOF SHINGLE. An interlocking metal sheet having an installed weather exposure less than 3 square feet (.279 m2) per sheet.
  MODIFIED BITUMEN ROOF COVERING. One or more layers of polymer-modified asphalt sheets. The sheet materials shall be fully adhered or mechanically attached to the substrate or held in place with an approved ballast layer.
  PENTHOUSE. An enclosed rooftop structure which is designed or used for human occupancy.
  POSITIVE ROOF DRAINAGE. The drainage condition in which consideration has been made for all loading deflections of the roof deck, including ponding instability, and additional slope has been provided to ensure drainage of the roof within 48 hours of precipitation.
  REROOFING. The process of recovering or replacing an existing roof covering. See "Roof recover" and "Roof replacement."
  ROOF ASSEMBLY. A system designed to provide weather protection and resistance to design loads. The system consists of a roof covering and roof deck or a single component serving as both the roof covering and the roof deck. A roof assembly includes the roof deck, vapor retarder, substrate or thermal barrier, insulation, vapor retarder and roof covering.
  ROOF COVERING. The covering applied to the roof deck for weather resistance, fire classification or appearance.
  ROOF COVERING SYSTEM. See "Roof assembly."
  ROOF DECK. The flat or sloped surface not including its supporting members or vertical supports.
  ROOF RECOVER. The process of installing an additional roof covering over a prepared existing roof covering without removing the existing roof covering.
  ROOF REPLACEMENT. The process of removing the existing roof covering, repairing any damaged substrate and installing a new roof covering.
  ROOF VENTILATION. The natural or mechanical process of supplying conditioned or unconditioned air to, or removing such air from, attics, cathedral ceilings or other enclosed spaces over which a roof assembly is installed.
  ROOFTOP STRUCTURE. An enclosed or unenclosed structure on or above the roof of any part of a building.
  SINGLE-PLY MEMBRANE. A roofing membrane that is field applied using one layer of membrane material (either homogeneous or composite) rather than multiple layers.
  UNDERLAYMENT. One or more layers of felt, sheathing paper, nonbituminous saturated felt or other approved material over which a steep-slope roof covering is applied.
Roof decks shall be covered with approved roof coverings secured to the building or structure in accordance with the provisions of this chapter. Roof coverings shall be designed, installed and maintained in accordance with this code and the approved manufacturer's instructions such that the roof covering shall serve to protect the building or structure.
Flashing shall be installed in such a manner so as to prevent moisture entering the wall and roof through joints in copings, through moisture-permeable materials and at intersections with parapet walls and other penetrations through the roof plane.
Flashing shall be installed at wall and roof intersections, at gutters, wherever there is a change in roof slope or direction and around roof openings. Where flashing is of metal, the metal shall be corrosion resistant with a thickness of not less than 0.019 inch (.483 mm) (No. 26 galvanized sheet).
Parapet walls shall be properly coped with noncombustible, weatherproof materials of a width no less than the thickness of the parapet wall.
Design and installation of roof drainage systems shall comply with the New York City Plumbing Code.
Gutters and leaders placed on the outside of buildings shall be of noncombustible, corrosion-resistant material, or a minimum of Schedule 40 plastic pipe.
Vertical sections of exterior leaders made from galvanized steel, galvanized wrought iron, cast iron, brass, or similar heavy material shall be permitted only for the first 15 feet (4572 mm) of leader extending up from grade, provided that the leader is securely anchored with offset clamps to the face of the building at no fewer than 2 points along the vertical section of the leader. Horizontal sections of exterior gutter made from such heavy materials shall not be permitted higher than 15 feet (4572 mm) above grade.
Intake and exhaust vents shall be provided in accordance with Section 1203.2 and the manufacturer's installation instructions.
Roof decks and roof coverings shall be designed for wind loads in accordance with Chapter 16 and Sections 1504.2, 1504.3 and 1504.4.
Asphalt shingles shall be designed for wind speeds in accordance with Section 1507.2.7.
Clay and concrete tile roof coverings shall be connected to the roof deck in accordance with Chapter 16.
Roof coverings installed on roofs in accordance with Section 1507 that are mechanically attached or adhered to the roof deck shall be designed to resist the design wind load pressures for cladding in Chapter 16.
Roof systems with built-up, modified bitumen, fully adhered or mechanically attached single-ply through fastened metal panel roof systems, and other types of membrane roof coverings shall also be tested in accordance with FM 4450, FM 4470, UL 580 or UL 1897.
Metal panel roof systems through fastened or standing seam shall be tested in accordance with UL 580 or ASTM E 1592.
Ballasted low-slope (roof slope < 2:12) single-ply roof system coverings installed in accordance with Section 1507 shall be designed in accordance with ANSI/SPRI RP-4.
Low-slope membrane roof systems metal edge securement, except gutters, installed in accordance with Section 1507, shall be designed in accordance with ANSI/SPRI ES-1, except the basic wind speed shall be determined in accordance with Chapter 16.
Roof coverings installed on low-slope roofs (roof slope < 2:12) in accordance with Section 1507 shall demonstrate physical integrity over the working life of the roof based upon 2,000 hours of exposure to accelerated weathering tests conducted in accordance with ASTM G 152, ASTM G 155 or ASTM G 154. Those roof coverings that are subject to cyclical flexural response due to wind loads shall not demonstrate any significant loss of tensile strength for unreinforced membranes or breaking strength for reinforced membranes when tested as herein required.
Roof coverings installed on low-slope roofs (roof slope < 2:12) in accordance with Section 1507 shall resist impact damage based on the results of tests conducted in accordance with ASTM D 3746, ASTM D 4272, CGSB 37-GP-52M or FM 4470.
Roof coverings on roofs or setbacks with slope equal to or less than two units vertical in 12 units horizontal (17 percent) shall have:
  1. a minimum initial solar reflectance of 0.7 in accordance with ASTM C1549 or ASTM E 1918, and a minimum thermal emittance of 0.75 as determined in accordance with ASTM C1371 or ASTM E 408; or
  2. a minimum SRI of 78 as determined in accordance with ASTM E 1980.
  Exceptions:
  1. Terraces on setbacks comprising less than 25 percent of the area of the largest floor plate in the building.
  2. Any portion of a roof covered by a green roof system, including such a system with agricultural plantings, in compliance with Section 1507.16.
  3. Any portion of a roof used as outdoor recreation space by the occupants of the building that is landscaped, covered by wood decking or covered with a walking surface or other protective surface, provided that such walking surface or protective surface has a minimum initial solar reflectance of 0.3 as determined in accordance with ASTM C1549 or ASTM E1918.
  4. Ballasted roofs, provided that the ballast has a minimum initial solar reflectance of 0.2 as determined in accordance with ASTM C1549 or ASTM E1918.
  5. Any portion of a roof that is under mechanical equipment, flush mounted solar panels lying directly on the roof surface, duckboarding, decking, platform, roof tank, cooling tower or any other rooftop structure or equipment exempted by rule by the commissioner.
  6. Any roof or portion of a roof composed of glass, metal, clay or concrete tile or plastic/rubber intended to simulate clay or concrete tile, wood, or slate.
  7. Any portion of a roof used by a school or daycare center as a playground for children.
  8. Any roof, if the amount of rooftop space not subject to exceptions 1 through 7 is in the aggregate less than 100 square feet.
Roof assemblies shall be divided into the classes defined below. Class A, B and C roof assemblies and roof coverings required to be listed by this section shall be tested in accordance with ASTM E 108 or UL 790. In addition, fire-retardant-treated wood roof coverings shall be tested in accordance with ASTM D 2898. The minimum roof coverings installed on buildings shall comply with Table 1505.1 based on the type of construction of the building.
Table 1505.1a,b
Minimum Roof Covering Classification for Types of Construction





















IA

IB

IIA

IIB

IIIA

IIIB

IV

VA

VB






















B

B

B

B

B

B

B

B

Cb





















For SI: 1 foot = 304.8 mm, 1 square foot = 0.0929 m2
a.
Unless otherwise required due to the location of the building within a fire district in accordance with Section D102.2.3 in Appendix D.
b.
Buildings that are not more than two stories in height and having not more than 6,000 square feet of projected roof area and where there is a minimum 10-foot fire-separation distance from the leading edge of the roof to a lot line on all sides of the building, except for street fronts or public ways, shall be permitted to have roofs of No. 1 cedar or redwood shakes and No. 1 shingles in accordance with Section 1505.6.
Class A roof assemblies are those that are effective against severe fire test exposure. Class A roof assemblies and roof coverings shall be listed and identified as Class A by an approved testing agency. Class A roof assemblies shall be permitted for use in buildings or structures of all types of construction.
  Exception: Class A roof assemblies include those with coverings of brick, masonry, slate, clay or concrete roof tile, exposed concrete roof deck, ferrous or copper shingles or sheets.
Class B roof assemblies are those that are effective against moderate fire-test exposure. Class B roof assemblies and roof coverings shall be listed and identified as Class B by an approved testing agency.
  Exception: Class B roof assemblies include those with coverings of metal sheets and shingles.
Class C roof assemblies are those that are effective against light fire-test exposure. Class C roof assemblies and roof coverings shall be listed and identified as Class C by an approved testing agency.
Roofs having a slope of more than 60 degrees (1.05 rad) to the horizontal shall be constructed of material having the same fire-resistance-rating as required for an exterior non-bearing wall of the building of which it is a part. When the slope is 60 degrees (1.05 rad) or less to the horizontal, the sloping roof shall be constructed as required for the roof of the building. Where the back of a false mansard is exposed to the outdoors, the back shall be covered with noncombustible material or with roof covering as required for the roof of the building.
Fire-retardant-treated wood shakes and shingles shall be treated by impregnation with chemicals by the full-cell vacuum-pressure process, in accordance with AWPA C1. Each bundle shall be marked to identify the manufactured unit and the manufacturer, and shall also be labeled to identify the classification of the material in accordance with the testing required in Section 1505.1, the treating company and the quality control agency.
Special purpose wood shingle or wood shake roofing shall conform with the grading and application requirements of Section 1507.8 or Section 1507.9. In addition, an underlayment of 0.625 inch (15.9 mm) Type X water-resistant gypsum backing board or gypsum sheathing shall be placed under minimum nominal 0.5-inch-thick (12.7 mm) wood structural panel solid sheathing or 1-inch (25 mm) nominal spaced sheathing.
The requirements set forth in this section shall apply to the application of roof-covering materials specified herein. Roof coverings shall be applied in accordance with this chapter and the manufacturer's installation instructions. Installation of roof coverings shall comply with the applicable provisions of Section 1507.
Roofs and roof coverings shall be of materials that are compatible with each other and with the building or structure to which the materials are applied.
Roof-covering materials shall conform to the applicable standards listed in this chapter. In the absence of applicable standards or where materials are of questionable suitability, testing by an approved agency shall be required by the commissioner to determine the character, quality and limitations of application of the materials.
Roof-covering materials shall be delivered in packages bearing the manufacturer's identifying marks and approved testing agency labels required in accordance with Section 1505. Bulk shipments of materials shall be accompanied with the same information issued in the form of a certificate or on a bill of lading by the manufacturer.
Roof coverings shall be applied in accordance with the applicable provisions of this section and the manufacturer's installation instructions.
The installation of asphalt shingles shall comply with the provisions of this section and Table 1507.2.
Table 1507.2
Asphalt Shingle Application


Component

Installation Requirement








1. Roof slope

Asphalt shingles shall only be used on roof slopes of two units vertical in 12 units horizontal (2:12) or greater. For roof slopes from two units vertical in 12 units horizontal (2:12) up to four units vertical in 12 units horizontal (4:12), double underlayment application is required in accordance with Section 1507.2.8.








2. Deck requirement

Asphalt shingles shall be fastened to solidly sheathed roofs.








3. Underlayment

Underlayment shall conform with ASTM D 226, Type 1, or ASTM D 4869, Type 1.








For roof slopes from two units vertical in 12 units horizontal (2:12), up to four units vertical in 12 units horizontal (4:12)

Underlayment shall be two layers applied in the following manner. Apply a minimum 19-inch strip or underlayment felt parallel to and starting at the eaves, fastened sufficiently to hold in place. Starting at the eave, apply 35-inch-wide sheets of underlayment overlapping successive sheets 19 inches and fastened sufficiently to hold in place.








For roof slopes from four units vertical in 12 units horizontal (4:12) or greater

Underlayment shall be one layer applied in the following manner. Underlayment shall be applied shingle fashion, parallel to and starting from the eave and lapped 2 inches, fastened only as necessary to hold in place.








In areas where the average daily temperature in January is 25°F or less or where there is a possibility of ice forming along the eaves causing a backup of water

A membrane that consists of at least two layers of underlayment cemented together or of a self-adhering polymer-modified bitumen sheet shall be used in lieu of normal underlayment and extend from the eave's edge to a point at least 24 inches inside the exterior wall line of the building.








4. Application









Attachment

Asphalt shingles shall have the minimum number of fasteners required by the manufacturer and Section 1504.1. Asphalt shingles shall be secured to the roof with not less than four fasteners per strip shingle or two fasteners per individual shingle. Where the roof slope exceeds 20 units vertical in 12 units horizontal (20:12), special methods of fastening are required.








Fasteners

Galvanized, stainless steel, aluminum or copper roofing nails, minimum 12-gage (0.015 inch) shank with a minimum 3/8-inch diameter head. Fasteners shall be long enough to penetrate into the sheathing 3/4 inch or through the thickness of the sheathing.








Flashings

In accordance with Section 1507.2.9.







For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, °C = [(°F) - 32]/1.8, 1 mile per hour = 1.609 km/h.
Asphalt shingles shall be fastened to solidly sheathed decks.
Asphalt shingles shall only be used on roof slopes of two units vertical in 12 units horizontal (17-percent slope) or greater. For roof slopes from two units vertical in 12 units horizontal (17-percent slope) up to four units vertical in 12 units horizontal (33-percent slope), double underlayment application is required in accordance with Section 1507.2.8.
Unless otherwise noted, required underlayment shall conform to ASTM D 226, Type I, or ASTM D 4869, Type I.
Self-adhering polymer modified bitumen sheet shall comply with ASTM D 1970.
Asphalt shingles shall have self-seal strips or be interlocking, and comply with ASTM D 225 or ASTM D 3462.
Fasteners for asphalt shingles shall be galvanized, stainless steel, aluminum or copper roofing nails, minimum 12 gage shank with a minimum 0.375 inch-diameter (9.5 mm) head, of a length to penetrate through the roofing materials and a minimum of 0.75 inch (19.1 mm) into the roof sheathing. Where the roof sheathing is less than 0.75 inch (19.1 mm) thick, the nails shall penetrate through the sheathing. Fasteners shall comply with ASTM F 1667.
Asphalt shingles shall have the minimum number of fasteners required by the manufacturer and Section 1504.1. Asphalt shingles shall be secured to the roof with not less than four fasteners per strip shingle or two fasteners per individual shingle. Where the roof slope exceeds 20 units vertical in 12 units horizontal (166 percent slope), special methods of fastening are required. For roofs located where the basic wind speed in accordance with Figure 1609 is 110 mph or greater, special methods of fastening are required. Special fastening methods shall be tested in accordance with ASTM D 3161, modified to use a wind speed of 110 mph.
For roof slopes from two units vertical in 12 units horizontal (17-percent slope), up to four units vertical in 12 units horizontal (33-percent slope), underlayment shall be two layers applied in the following manner. Apply a minimum 19-inch-wide (483 mm) strip of underlayment felt parallel with and starting at the eaves, fastened sufficiently to hold in place. Starting at the eave, apply 36-inch-wide (914 mm) sheets of underlayment overlapping successive sheets 19 inches (483 mm) and fastened sufficiently to hold in place. For roof slopes of four units vertical in 12 units horizontal (33-percent slope) or greater, underlayment shall be one layer applied in the following manner. Underlayment shall be applied shingle fashion, parallel to and starting from the eave and lapped 2 inches (51 mm), fastened only as necessary to hold in place.
Where there is a possibility of ice forming along the eaves causing a backup of water, a membrane that consists of at least two layers of underlayment cemented together or of a self-adhering polymer modified bitumen sheet shall be used in lieu of normal underlayment and extend from the eave's edge to a point at least 24 inches (610 mm) inside the exterior wall line of the building.
  Exception: Detached accessory structures that contain no conditioned floor area.
Flashing for asphalt shingles shall comply with this section. Flashing shall be applied in accordance with this section and the asphalt shingle manufacturer's printed instructions.
Base and cap flashing shall be installed in accordance with the manufacturer's instructions. Base flashing shall be of either corrosion-resistant metal of minimum nominal 0.019-inch (0.483 mm) thickness or mineral-surfaced roll roofing weighing a minimum of 77 pounds per 100 square feet (3.76 kg/m 2 ). Cap flashing shall be corrosion-resistant metal of minimum nominal 0.019-inch (0.483 mm) thickness.
Valley linings shall be installed in accordance with the manufacturer's instructions before applying shingles. Valley linings of the following types shall be permitted:
  1. For open valleys (valley lining exposed) lined with metal, the valley lining shall be at least 16 inches (406 mm) wide and of any of the corrosion-resistant metals in Table 1507.2.9.2.
  2. For open valleys, valley lining of two plies of mineral-surfaced roll roofing shall be permitted. The bottom layer shall be 18 inches (457 mm) and the top layer a minimum of 36 inches (914 mm) wide.
  3. For closed valleys (valleys covered with shingles), valley lining of one ply of smooth roll roofing complying with ASTM D 224 and at least 36 inches (914 mm) wide or types as described in Items 1 and 2 above shall be permitted. Specialty underlayment shall comply with ASTM D 1970.
Table 1507.2.9.2
Valley Lining Material


Material

Minimum
Thickness

Gage

Weight












Copper



16 oz












Aluminum

0.024 in.














Stainless steel


28













Galvanized steel

0.0179 in.

26 (zinc-coated G90)













Zinc alloy

0.027 in.














Lead



2.5 pounds












Painted terne



20 pounds











For SI: 1 inch = 25.4 mm, 1 pound = 0.454 kg, 1 ounce = 28.35 g.
Provide drip edge at eaves and gables of shingle roofs. Overlap to be a minimum of 2 inches (51 mm). Eave drip edges shall extend 0.25 inch (6.4 mm) below sheathing and extend back on the roof a minimum of 2 inches (51 mm). Drip edge shall be mechanically fastened a maximum of 12 inches (305 mm) o.c. A cricket or saddle shall be installed on the ridge side of any chimney greater than 30 inches (762 mm) wide. Cricket or saddle coverings shall be sheet metal or of the same material as the roof covering.
The installation of clay and concrete tile shall comply with the provisions of this section.
Concrete and clay tile shall be installed only over solid sheathing or spaced structural sheathing boards.
Clay and concrete roof tile shall be installed on roof slopes of 2 1 / 2 units vertical in 12 units horizontal (21-percent slope) or greater. For roof slopes from 2 1 / 2 units vertical in 12 units horizontal (21-percent slope) to four units vertical in 12 units horizontal (33-percent slope), double underlayment application is required in accordance with Section 1507.3.3.
Unless otherwise noted, required underlayment shall conform to: ASTM D 226, Type II; ASTM D 2626 or ASTM D 249 Type I mineral-surfaced roll roofing.
For roof slopes from 21/2 units vertical in 12 units horizontal (21-percent slope), up to four units vertical in 12 units horizontal (33-percent slope), underlayment shall be a minimum of two layers applied as follows:
  1. Starting at the eave, a 19-inch (483 mm) strip of underlayment shall be applied parallel with the eave and fastened sufficiently in place.
  2. Starting at the eave, 36-inch-wide (914 mm) strips of underlayment felt shall be applied overlapping successive sheets 19 inches (483 mm) and fastened sufficiently in place.
For roof slopes of four units vertical in 12 units horizontal (33-percent slope) or greater, underlayment shall be a minimum of one layer of underlayment felt applied shingle fashion, parallel to, and starting from the eaves and lapped 2 inches (51 mm), fastened only as necessary to hold in place.
Clay roof tile shall comply with ASTM C 1167.
Concrete roof tiles shall be in accordance with the physical test requirements as follows:
  1. The transverse strength of tiles shall be determined according to Section 6.3 of ASTM C 1167 and in accordance with Table 1507.3.5.
  2. The absorption of concrete roof tiles shall be according to Section 8 of ASTM C 140. Roof tiles shall absorb not more than 15 percent of the dry weight of the tile during a 24-hour immersion test.
  3. Roof tiles shall be tested for freeze/thaw resistance according to Section 8 of ASTM C67. Roof tiles shall show no breakage and not have more than 1 percent loss in dry weight of any individual concrete roof tile.
Table 1507.3.5
Transverse Breaking Strength of Concrete Roof Tile (lbs.)


Tile Profile

Dry
________________________________________






Average of five tiles
Individual tile








High profile

400

350










Medium profile

300

250










Flat profile

300

250









For SI: 1 pound = 4.45 N.
Tile fasteners shall be corrosion resistant and not less than 11 gage, 5 / 1 6 -inch (8.0 mm) head, and of sufficient length to penetrate the deck a minimum of 0.75 inch (19.1 mm) or through the thickness of the deck, whichever is less. Attaching wire for clay or concrete tile shall not be smaller than 0.083 inch (2.1 mm). Perimeter fastening areas include three tile courses but not less than 36 inches (914 mm) from either side of hips or ridges and edges of eaves and gable rakes.
Clay and concrete roof tiles shall be fastened in accordance with Table 1507.3.7.
Tile shall be applied according to the manufacturer's installation instructions, based on the following:
  1. Climatic conditions.
  2. Roof slope.
  3. Underlayment system.
  4. Type of tile being installed.
At the juncture of the roof vertical surfaces, flashing and counterflashing shall be provided in accordance with the manufacturer's installation instructions, and where of metal, shall not be less than 0.019-inch (0.48 mm) (No. 26 galvanized sheet gage) corrosion-resistant. The valley flashing shall extend at least 11 inches (279 mm) from the centerline each way and have a splash diverter rib not less than 1 inch (25 mm) high at the flow line formed as part of the flashing. Sections of flashing shall have an end lap of not less than 4 inches (102 mm). For roof slopes of three units vertical in 12 units horizontal (25-percent slope) and over, the valley flashing shall have a 36-inch-wide (914 mm) underlayment of one layer of Type I underlayment running the full length of the valley, in addition to other required underlayment. Where there is a possibility of ice forming along the eaves causing a backup of water, the metal valley flashing underlayment shall be solid cemented to the roofing underlayment for slopes under seven units vertical in 12 units horizontal (58-percent slope) or of self-adhering polymer modified bitumen sheet.
The installation of metal roof panels shall comply with the provisions of this section.
Metal roof panel roof coverings shall be applied to a solid or closely fitted deck, except where the roof covering is specifically designed to be applied to spaced supports.
The minimum slope for lapped, nonsoldered seam metal roofs without applied lap sealant shall be three units vertical in 12 units horizontal (25-percent slope). The minimum slope for lapped, nonsoldered seam metal roofs with applied lap sealant shall be one-half vertical unit in 12 units horizontal (4-percent slope). The minimum slope for standing seam of roof systems shall be one-quarter unit vertical in 12 units horizontal (2-percent slope).
Metal-sheet roof covering systems that incorporate supporting structural members shall be designed in accordance with Chapter 22. Metal-sheet roof coverings installed over structural decking shall comply with Table 1507.4.3.

TABLE 1507.4.3 METAL ROOF COVERINGS

ROOF COVERING TYPE STANDARD APPLICATION
RATE/THICKNESS
Aluminum ASTM B 209, 0.024 inch minimum thickness
for roll-formed panels and 0.019 inch minimum thickness for press-formed shingles.
Aluminum-zinc
alloy coated steel
ASTM A 792 AZ 50
Copper 16 oz./sq. ft. for metal-sheet roof-covering
systems; 12 oz./sq. ft. for preformed metal
shingle systems.
Galvanized steel ASTM A 653 G-90 zinc-coated, 0.013-inch-thick minimum
Lead-coated copper ASTM B 101
Hard lead 2 lbs./sq. ft.
Soft lead 3 lbs./sq. ft.
Prepainted steel ASTM A 755
Terne (tin) and terne-
coated stainless
Terne coating of 40 lbs. per double base box,
field painted where applicable in accordance
with manufacturer''s installation instructions.

For SI: 1 ounce per square foot = 0.0026 kg/m2,
1 pound per square foot = 4.882 kg/m2, 1 inch = 25.4 mm,
1 pound = 0.454 kg.
Metal roofing fastened directly to steel framing shall be attached by approved manufacturers' fasteners. In the absence of manufacturer recommendations, all of the following fasteners shall be used:
  1. Galvanized fasteners shall be used for galvanized roofs.
  2. 300 series stainless-steel fasteners shall be used for copper roofs.
  3. Stainless-steel fasteners are acceptable for all types of metal roofs.
The installation of metal roof shingles shall comply with the provisions of this section.
Metal roof shingles shall be applied to a solid or closely fitted deck, except where the roof covering is specifically designed to be applied to spaced sheathing.
Metal roof shingles shall not be installed on roof slopes below three units vertical in 12 units horizontal (25-percent slope).
Underlayment shall conform to ASTM D 226, Type I. Where there is a possibility of ice forming along the eaves causing a backup of water, an ice barrier that consists of at least two layers of underlayment cemented together or of a self-adhering polymer-modified bitumen sheet, shall be used in lieu of normal underlayment and extend from the eave's edge to a point at least 24 inches (610 mm) inside the exterior wall line of the building.
  Exception: Detached accessory structures that contain no conditioned floor area.
Metal roof shingle roof coverings shall comply with Table 1507.4.3.
Metal roof shingles shall be secured to the roof in accordance with the approved manufacturer's installation instructions.
Roof valley flashing shall be of corrosion-resistant metal of the same material as the roof covering or shall comply with the standards in Table 1507.4.3. The valley flashing shall extend at least 8 inches (203 mm) from the centerline each way and shall have a splash diverter rib not less than 0.75 inch (19.1 mm) high at the flow line formed as part of the flashing. Sections of flashing shall have an end lap of not less than 4 inches (102 mm). Where there is a possibility of ice forming along the eaves causing a backup of water, the metal valley flashing shall have a 36-inch-wide (914 mm) underlayment directly under it consisting of one layer of underlayment running the full length of the valley, in addition to underlayment required for metal roof shingles. The metal valley flashing underlayment shall be solid cemented to the roofing underlayment for roof slopes under seven units vertical in 12 units horizontal (58-percent slope) or of self-adhering polymer-modified bitumen sheet.
The installation of mineral-surfaced roll roofing shall comply with this section.
Mineral-surfaced roll roofing shall be fastened to solidly sheathed roofs.
Mineral-surfaced roll roofing shall not be applied on roof slopes below one unit vertical in 12 units horizontal (8-percent slope).
Underlayment shall conform to ASTM D 226, Type I. Where there is a possibility of ice forming along the eaves causing a backup of water, an ice barrier that consists of at least two layers of underlayment cemented together or of a self-adhering polymer-modified bitumen sheet, shall extend from the eave's edge to a point at least 24 inches (610 mm) inside the exterior wall line of the building.
  Exception: Detached accessory structures that contain no conditioned floor area.
Mineral-surfaced roll roofing shall conform to ASTM D 224, ASTM D 249, ASTM D 371 or ASTM D 3909.
The installation of slate shingles shall comply with the provisions of this section.
Slate shingles shall be fastened to solidly sheathed roofs.
Slate shingles shall only be used on slopes of four units vertical in 12 units horizontal (4:12) or greater.
Underlayment shall comply with ASTM D 226, Type II. Where there is a possibility of ice forming along the eaves causing a backup of water, an ice barrier that consists of at least two layers of underlayment cemented together or of a self-adhering polymer-modified bitumen sheet, shall extend from the eave's edge to a point at least 24 inches (610 mm) inside the exterior wall line of the building.
  Exception: Detached accessory structures that contain no conditioned floor area.
Slate shingles shall comply with ASTM C 406.
Minimum headlap for slate shingles shall be in accordance with Table 1507.7.5. Slate shingles shall be secured to the roof with two fasteners per slate.
Table 1507.7.5
Slate Shingle Headlap


Slope

Headlap
(inches)








4:12 < slope < 8:12

4








8:12 < slope < 20:12

3








slope ≥ 20:12

2







For SI: 1 inch = 25.4 mm.
Flashing and counterflashing shall be made with sheet metal. Valley flashing shall be a minimum of 15 inches (381 mm) wide. Valley and flashing metal shall be a minimum uncoated thickness of 0.0179-inch (0.455 mm) zinc-coated G90. Chimneys, stucco or brick walls shall have a minimum of two plies of felt for a cap flashing consisting of a 4-inch-wide (102 mm) strip of felt set in plastic cement and extending 1 inch (25 mm) above the first felt and a top coating of plastic cement. The felt shall extend over the base flashing 2 inches (51 mm).
The installation of wood shingles shall comply with the provisions of this section and Table 1507.8.
Table 1507.8
Wood Shingle and Shake Installation


Roof Item

Wood Shingles

Wood Shakes










1. Roof slope

Wood shingles shall be installed on slopes of three units vertical in 12 units horizontal (3:12) or greater.

Wood shakes shall be installed on slopes of four units vertical in 12 units horizontal (4:12) or greater.










2. Deck requirement












Temperate climate

Shingles shall be applied to roofs with solid or spaced sheathing. Where spaced sheathing is used, sheathing boards shall not be 4 less than 1" × 4" nominal dimensions and shall be spaced on center equal to the weather exposure to coincide with the placement of fasteners.

Shakes shall be aplied to roofs with solid or spaced sheathing. Where spaced sheathing is used, sheathing boards shall not be less than 1" × 4" nominal dimensions and shall be spaced on center equal to the weather exposure to coincide with the placement of fasteners. When
1" × 4" spaced sheathing is installed at 10 inches, boards must be installed between the sheathing boards.











In areas where the average daily temperature in January is 25°F or less or where there is a possibility of ice forming along the eaves causing a backup of water.

Solid sheathing required.

Solid sheathing is required.










3. Interlayment

No requirements.

Interlayment shall comply with ASTM D 226, Type 1.










4. Underlayment












Temperate climate

Underlayment shall comply with ASTM D 226, Type 1.

Underlayment shall comply with ASTM D 226, Type 1.










In areas where the average daily temperature in January is 25°F or less or where there is a possibility of ice forming along the eaves causing a backup of water.

An ice shield that consists of at least two layers of underlayment cemented together or of a self-adhering polymer-modified bitumen sheet shall extend from the eave's edge to a point at least 24 inches inside the exterior wall line of the building.

An ice shield that consists of at least two layers of underlayment cemented together or of a self-adhering polymer-modified bitumen sheet shall extend from the eave's edge to a point at least 24 inches inside the exterior wall line of the building.










5. Application












Attachment

Fasteners for wood shingles shall be corrosion resistant with a minimum penetration of 0.75 inch into the sheathing. For sheathing less than 0.5 inch thick, the fasteners shall extend through the sheathing.

Fasteners for wood shakes shall be corrosion resistant with a minimum penetration of 0.75 inch into the sheathing. For sheathing less than 0.5 inch thick, the fasteners shall extend through the sheathing.










No. of fasteners

Two per shingle.

Two per shake.










Exposure

Weather exposures shall not exceed those set forth in Table 1507.8.6

Weather exposures shall not exceed those set forth in Table 1507.9.7










Method

Shingles shall be laid with a side lap of not less than 1.5 inches between joints in courses, and no two joints in any three adjacent courses shall be in direct alignment. Spacing between shingles shall be 0.25 to 0.375 inch.

Shakes shall be laid with a side lap of not less than 1.5 inches between joints in adjacent courses. Spacing between shakes shall not be less than 0.375 inch or more than 0.625 inch for shakes and tapersawn shakes of naturally durable wood and shall be 0.25 to 0.375 inch for preservative taper sawn shakes.










Flashing

In accordance with Section 1507.8.7.

In accordance with Section 1507.9.8.









For SI: 1 inch = 25.4 mm, °C = [(°F) - 32]/1.8.
Wood shingles shall be installed on solid or spaced sheathing. Where spaced sheathing is used, sheathing boards shall not be less than 1-inch by 4-inch (25 mm by 102 mm) nominal dimensions and shall be spaced on centers equal to the weather exposure to coincide with the placement of fasteners.
Solid sheathing is required where there is a possibility of ice forming along the eaves causing a backup of water.
Wood shingles shall be installed on slopes of three units vertical in 12 units horizontal (25-percent slope) or greater.
Underlayment shall comply with ASTM D 226, Type I. Where there is a possibility of ice forming along the eaves causing a backup of water, an ice barrier that consists of at least two layers of underlayment cemented together or of a self-adhering polymer-modified bitumen sheet shall extend from the eave's edge to a point at least 24 inches (610 mm) inside the exterior wall line of the building.
  Exception: Detached accessory structures that contain no conditioned floor area.
Wood shingles shall be of naturally durable wood and comply with the requirements of Table 1507.8.4.
Table 1507.8.4
Wood Shingle Material Requirements


Material

Applicable
Minimum Grades

Grading Rules










Wood shingles of naturally
durable wood


1, 2 or 3

CSSB









CSSB = Cedar Shake and Shingle Bureau
Fasteners for wood shingles shall be corrosion resistant with a minimum penetration of 0.75 inch (19.1 mm) into the sheathing. For sheathing less than 0.5 inch (12.7 mm) in thickness, the fasteners shall extend through the sheathing. Each shingle shall be attached with a minimum of two fasteners.
Wood shingles shall be laid with a side lap not less than 1.5 inches (38 mm) between joints in adjacent courses, and not be in direct alignment in alternate courses. Spacing between shingles shall be 0.25 to 0.375 inches (6.4 to 9.5 mm). Weather exposure for wood shingles shall not exceed that set in Table 1507.8.6.
Table 1507.8.6
Wood Shingle Weather Exposure and Roof Slope


Roofing Material

Length
(inches)

Grade

Exposure (inches)
________________________________________








3:12 pitch
to < 4:12
4:12 pitch
or steeper














  
16
  

No. 1
No. 2
No. 3

3.75
3.5
3

5
4
3.5














Shingles of naturally durable
wood


  
18
  

No. 1
No. 2
No. 3

4.25
4
3.5

5.5
4.5
4















  
24
  

No. 1
No. 2
No. 3

5.75
5.5
5

7.5
6.5
5.5













For SI: 1 inch = 25.4 mm.
At the juncture of the roof and vertical surfaces, flashing and counterflashing shall be provided in accordance with the manufacturer's installation instructions, and where of metal, shall not be less than 0.019-inch (0.48 mm) (No. 26 galvanized sheet gage) corrosion-resistant metal. The valley flashing shall extend at least 11 inches (279 mm) from the centerline each way and have a splash diverter rib not less than 1 inch (25 mm) high at the flow line formed as part of the flashing. Sections of flashing shall have an end lap of not less than 4 inches (102 mm). For roof slopes of three units vertical in 12 units horizontal (25-percent slope) and over, the valley flashing shall have a 36-inch-wide (914 mm) underlayment of one layer of Type I underlayment running the full length of the valley, in addition to other required underlayment. Where there is a possibility of ice forming along the eaves causing a backup of water, the metal valley flashing underlayment shall be solid cemented to the roofing underlayment for slopes under seven units vertical in 12 units horizontal (58-percent slope).
The installation of wood shakes shall comply with the provisions of this section and Table 1507.8.
Wood shakes shall only be used on solid or spaced sheathing. Where spaced sheathing is used, sheathing boards shall not be less than 1-inch by 4-inch (25 mm by 102 mm) nominal dimensions and shall be spaced on centers equal to the weather exposure to coincide with the placement of fasteners. Where 1-inch by 4-inch (25 mm by 102 mm) spaced sheathing is installed at 10 inches (254 mm) o.c., additional 1-inch by 4-inch (25 mm by 102 mm) boards shall be installed between the sheathing boards.
Solid sheathing is required in areas where the average daily temperature in January is 25°F (-4°C) or less or where there is a possibility of ice forming along the eaves causing a backup of water.
Wood shakes shall only be used on slopes of four units vertical in 12 units horizontal (33-percent slope) or greater.
Underlayment shall comply with ASTM D 226, Type I. Where there is a possibility of ice forming along the eaves causing a backup of water, an ice barrier that consists of at least two layers of underlayment cemented together or a self-adhering polymer-modified bitumen sheet shall extend from the edge of the eave to a point at least 24 inches (610 mm) inside the exterior wall line of the building.
  Exception: Detached accessory structures that contain no conditioned floor area.
Interlayment shall comply with ASTM D 226, Type I.
Wood shakes shall comply with the requirements of Table 1507.9.5.
Table 1507.9.5
Wood Shake Material Requirements


Material

Minimum
Grades

Applicable
Grading Rules










Wood shakes of naturally durable wood

1

CSSB










Taper sawn shakes of naturally durable wood

1 or 2

CSSB










Preservative-treated shakes and shingles of naturally durable wood

1

CSSB










Fire-retardant-treated shakes and shingles of naturally durable wood

1

CSSB










Preservative-treated taper sawn shakes of Southern yellow pine treated in accordance with AWPA Standard C2

1 or 2

TFS









CSSB = Cedar Shake and Shingle Bureau.
TFS = Forest Products Laboratory of the Texas Forest Services.
Fasteners for wood shakes shall be corrosion resistant with a minimum penetration of 0.75 inch (19.1 mm) into the sheathing. For sheathing less than 0.5 inch (12.7 mm) in thickness, the fasteners shall extend through the sheathing. Each shake shall be attached with a minimum of two fasteners.
Wood shakes shall be laid with a side lap not less than 1.5 inches (38 mm) between joints in adjacent courses. Spacing between shakes in the same course shall be 0.375 to 0.625 inches (9.5 to 15.9 mm) for shakes and taper sawn shakes of naturally durable wood and shall be 0.25 to 0.375 inch (6.4 to 9.5 mm) for preservative taper sawn shakes. Weather exposure for wood shakes shall not exceed those set in Table 1507.9.7.
Table 1507.9.7
Wood Shake Weather Exposure and Roof Slope


Roofing Material

Length
(inches)

Grade

Exposure
(inches)
4:12 Pitch
or Steeper












Shakes of naturally durable wood

18
24

No. 1
No. 1

7.5
10a












Preservative-treated taper sawn shakes of Southern yellow pine

18
24

18
24

No. 1
No. 1

No. 2
No. 2

7.5
10

5.5
7.5












Taper sawn shakes of naturally durable wood

18
24

18
24

No. 1
No. 1

No. 2
No. 2

7.5
10

5.5
7.5











For SI: 1 inch = 25.4 mm.
a. For 24-inch by 0.375-inch handsplit shakes, the maximum exposure is 7.5 inches.
At the juncture of the roof and vertical surfaces, flashing and counter-flashing shall be provided in accordance with the manufacturer's installation instructions, and where of metal, shall not be less than 0.019-inch (0.48 mm) (No. 26 galvanized sheet gage) corrosion-resistant metal. The valley flashing shall extend at least 11 inches (279 mm) from the centerline each way and have a splash diverter rib not less than 1 inch (25 mm) high at the flow line formed as part of the flashing. Sections of flashing shall have an end lap of not less than 4 inches (102 mm). For roof slopes of 3 units vertical in 12 units horizontal (25-percent slope) and over, the valley flashing shall have a 36-inch-wide (914 mm) underlayment of one layer of Type I underlayment running the full length of the valley, in addition to other required underlayment. Where there is a possibility of ice forming along the eaves causing a backup of water, the metal valley flashing underlayment shall be solid cemented to the roofing underlayment for slopes under seven units vertical in 12 units horizontal (58-percent slope).
The installation of built-up roofs shall comply with the provisions of this section.
Built-up roofs shall have a slope designed and built to provide positive roof drainage.
Built-up roof covering materials shall comply with the standards in Table 1507.10.2.
Table 1507.10.2
Built-Up Roofing Material Standards


Material Standard

Standard








Acrylic coating used in roofing

ASTM D 6083








Aggregate surfacing

ASTM D 1863








Asphalt adhesive used in roofing

ASTM D 3747








Asphalt cements used in roofing

ASTM D 3019; D 2822; D 4586








Asphalt-coated glass fiber base sheet

ASTM D 4601








Asphalt coatings used in roofing

ASTM D 1227; D 2823; D 4479








Asphalt glass felt

ASTM D 2178








Asphalt primer used in roofing

ASTM D 41








Asphalt-saturated and asphalt-coated organic felt base sheet

ASTM D 2626








Asphalt-saturated organic felt (perforated)

ASTM D 226








Asphalt used in roofing

ASTM D 312








Coal-tar cements used in roofing

ASTM D 4022; D 5643








Coal-tar saturated organic felt

ASTM D 227








Coal-tar pitch used in roofing

ASTM D 450; Type I or II








Coal-tar primer used in roofing, damproofing and waterproofing

ASTM D 43








Glass mat, coal tar

ASTM D 4990








Glass mat, venting type

ASTM D 4897








Mineral-surfaced inorganic cap sheet

ASTM D 3909








Thermoplastic fabrics used in roofing

ASTM D 5665, D 5726







The installation of modified bitumen roofing shall comply with the provisions of this section.
Modified bitumen membrane roofs shall have a slope designed and built to provide positive roof drainage.
Modified bitumen roof coverings shall comply with CGSB 37-GP-56M, ASTM D 6162, ASTM D 6163, ASTM D 6164, ASTM D 6222, ASTM D 6223 and ASTM D 6298.
The installation of thermoset single-ply roofing shall comply with the provisions of this section.
Thermoset single-ply membrane roofs shall have a slope designed and built to provide positive roof drainage.
Thermoset single-ply roof coverings shall comply with RMA RP-1, RP-2 or RP-3, or ASTM D 4637, ASTM D 5019 or CGSB 37-GP-52M.
The installation of thermoplastic single-ply roofing shall comply with the provisions of this section.
Thermoplastic single-ply membrane roofs shall have a slope designed and built to provide positive roof drainage.
Thermoplastic single-ply roof coverings shall comply with ASTM D 4434 or CGSB 37-GP-54M.
The installation of sprayed polyurethane foam roofing shall comply with the provisions of this section.
Sprayed polyurethane foam roofs shall have a slope designed and built to provide positive roof drainage.
Spray-applied polyurethane foam insulation shall comply with ASTM C 1029.
Foamed-in-place roof insulation shall be installed in accordance with the manufacturer's instructions. A liquid-applied protective coating that complies with Section 1507.15 shall be applied no less than 2 hours nor more than 72 hours following the application of the foam.
Foam plastic materials and installation shall comply with Chapter 26.
The installation of liquid-applied coatings shall comply with the provisions of this section.
Liquid-applied roofs shall have a slope designed and built to provide positive roof drainage.
Liquid-applied roof coatings shall comply with ASTM C 836, ASTM C 957, ASTM D 6083, ASTM D 1227 or ASTM D 3468.
The installation of a green roof system shall comply with this section.
Roof covering shall conform with Sections 1507.10, 1507.11, 1507.12, 1507.13, or 1507.15.
Green roof systems shall have a design slope in accordance with the roof covering utilized.
Green roof systems shall comply with required standards for the roof covering and good practice standards for the landscape material components. Either an affidavit from the roof covering manufacturer, stating review and acceptance of the final work, shall be provided prior to sign-off of construction or a special inspection by the professional architect or engineer shall be performed.
The use of above-deck thermal insulation shall be permitted provided such insulation is covered with an approved roof covering and passes the tests of FM 4450 or UL 1256 when tested as an assembly.
  Exception: Foam plastic roof insulation shall conform to the material and installation requirements of Chapter 26.
Cellulosic fiberboard roof insulation shall conform to the material and installation requirements of Chapter 23.
The provisions of this section shall govern the construction of rooftop structures. All rooftop structures shall be subject to the roof area coverage limitations and building height requirements of Chapter 5. Rooftop structures shall be constructed with materials as required for the building, except as provided for in this section.
Bulkheads and penthouses shall comply with the construction requirements of Section 1509.2.
Bulkheads and penthouses shall be constructed with walls, floors and roof as required for the building.
  Exceptions: Where the total aggregate area of all rooftop structures does not exceed 331/3 percent of the area of the roof of the building upon which they are erected; the following shall apply:
  1. Bulkheads on buildings of Type I and II construction. The exterior walls and roofs of such bulkheads with a fire separation distance of more than 5 feet (1524 mm) and less than 20 feet (6096 mm) shall be of at least 1-hour fire-resistance-rated noncombustible construction. Walls and roofs with a fire separation distance of 20 feet (6096 mm) or greater shall be of noncombustible construction. Interior framing and walls shall be of noncombustible construction.
  2. Bulkheads on buildings of Type III, IV and V construction. The exterior walls of such bulkheads with a fire separation distance of more than 5 feet (1524 mm) and less than 20 feet (6096 mm) shall be at least 1-hour fire-resistance-rated construction. Walls with a fire separation distance of 20 feet (6096 mm) or greater from a common property line shall be of Type IV or noncombustible construction. Roofs shall be constructed of materials and fire-resistance rated as required in Table 601. Interior framing and walls shall be Type IV or noncombustible construction.
  3. Unprotected noncombustible enclosures housing only mechanical equipment and located with a minimum fire separation distance of 20 feet (6096 mm) shall be permitted.
  4. On one-story buildings, combustible unroofed mechanical equipment screens, fences or similar enclosures are permitted where located with a fire separation distance of at least 20 feet (6096 mm) from adjacent property lines and where not exceeding 4 feet (1219 mm) in height above the roof surface.
Enclosed walls of penthouses shall comply with the requirements for exterior walls as per Table 601 and 602 for the construction class of the building on which they are erected. Roofs of penthouses shall comply with the requirements for roof construction of Table 601 and Chapter 15 of this code.
An enclosed rooftop structure not intended for human occupancy shall not be used for purposes other than shelter of mechanical equipment or shelter of vertical shaft openings in the roof. Provisions such as louvers, louver blades or flashing shall be made to protect the mechanical equipment and the building interior from the elements.
Tanks having a capacity of more than 500 gallons (2 m 3 ) placed in or on a building shall be supported on masonry, reinforced concrete, steel or Type IV construction provided that, where such supports are located in the building above the lowest story, the support shall be fire-resistance rated as required for Type IA construction.
Such tanks shall have in the bottom or on the side near the bottom, a pipe or outlet, fitted with a suitable quick opening valve for discharging the contents in an emergency through an adequate drain.
Such tanks shall not be placed over or near a line of stairs or an elevator shaft, unless there is a solid roof or floor underneath the tank.
Unenclosed roof tanks shall have covers sloping toward the outer edges.
Cooling towers in excess of 250 square feet (23.2 m2) in base area or in excess of 15 feet (4572 mm) high where located on buildings more than 50 feet (15 240 mm) high shall be of noncombustible construction.
  Exceptions:
  1. Drip boards and the enclosing construction of wood not less than 1 inch (25 mm) nominal thickness, provided the wood is covered on the exterior of the tower with noncombustible material.
  2. Filling and drift eliminators may be of combustible material if the towers are provided with automatic sprinkler protection complying with Section 903 of this code.
Any steeple, minaret, spire, dome or cupola shall be of a type of construction not less in fire-resistance rating than required for the building to which it is attached except that any such steeple, minaret, spire, dome or cupola that exceeds 85 feet (25 908 mm) in height above grade, or exceeds 200 square feet (18.6 m 2 ) in horizontal area or is used for any purpose other than a belfry or an architectural embellishment shall be constructed of and supported on Type I or II construction.
Any steeple, minaret, spire, dome or cupola that exceeds 60 feet (18 288 mm) in height above the highest point at which it comes in contact with the roof, or that exceeds 200 square feet (18.6 m 2 ) in area at any horizontal section, or which is intended to be used for any purpose other than a belfry or architectural embellishment, shall be entirely constructed of and supported by noncombustible materials. Such structures shall be separated from the building below by construction having a fire-resistance rating of not less than 1.5 hours with openings protected with a minimum 1.5-hour fire-protection rating. Such structures placed above the roof of any building more than 50 feet (15 240 mm) in height, shall be of noncombustible material and shall be supported by construction of noncombustible material.
Steeples, minarets, and spires where enclosed shall have exterior walls as required for the building to which they are attached. The roof covering of spires shall be of a class of roof covering as required for the main roof of the rest of the structure.
Dormers shall have exterior walls as required for the building to which they are attached. The roof covering of dormers shall be of a class of roof covering as required for the main roof of the rest of the structure.
Greenhouses used for the cultivation of plants, on the roofs of buildings other than buildings of Type V construction, shall be constructed of noncombustible framework and shall be glazed with plain or wire glass, or light transmitting plastic glazing complying with the requirements of Section 2606. The floors of greenhouses shall be constructed to be at least equal to the requirements for roof construction on Table 601 for the construction class of the building on which it is located.
Buildings greater than 22 feet (6706 mm) in height with roof slopes less than 2.4 units vertical in 12 units horizontal (20 percent slope) shall be provided with a parapet, railing, fence, or combination thereof, not less than 42 inches (1067 mm) in height. Railings or fences may be located inward from the face of the exterior wall a distance not exceeding 6 feet (1829 mm). Railings or fences shall be of noncombustible material, except on buildings of Type V construction. Railings shall be constructed to comply with the requirements of Sections 1012 and 1607.7.
Rooftops used for recreational purposes shall be provided with wire fencing at least 10 feet (3048 mm) in height. Openings in the fence shall not permit the passage of a 4-inch diameter (102 mm) sphere. Where ball games are played on rooftops the wire fencing shall be extended to provide an overhead closure.
The following roof structures may be constructed of combustible material if less than 12 feet (1658 mm) high above the roof: antenna supports; flagpoles; clothes drying frames; duckboarding, decking or platforms that do not cover more than 20 percent of the contiguous roof area at that level.
Materials and methods of application used for recovering or replacing an existing roof covering shall comply with the requirements of Chapter 15.
  Exception: Section 1504.8 shall not apply if the area to be recovered or replaced is less than 50 percent of the roof area and less than 500 square feet.
Structural roof components shall be capable of supporting the roof-covering system and the material and equipment loads that will be encountered during installation of the system.
New roof coverings shall not be installed without first removing all existing layers of roof coverings where any of the following conditions occur:
  1. Where the existing roof or roof covering is water soaked or has deteriorated to the point that the existing roof or roof covering is not adequate as a base for additional roofing.
  2. Where the existing roof covering is wood shake, slate, clay, cement or asbestos-cement tile.
  3. Where the existing roof has two or more applications of any type of roof covering.
  Exceptions:
  1. Complete and separate roofing systems, such as standing-seam metal roof systems, that are designed to transmit the roof loads directly to the building's structural system and that do not rely on existing roofs and roof coverings for support, shall not require the removal of existing roof coverings.
  2. Metal panel, metal shingle, and concrete and clay tile roof coverings shall be permitted to be installed over existing wood shake roofs when applied in accordance with Section 1510.4.
Where the application of a new roof covering over wood shingle or shake roofs creates a combustible concealed space, the entire existing surface shall be covered with gypsum board, mineral fiber, glass fiber or other approved materials securely fastened in place.
Existing slate, clay or cement tile shall be permitted for reinstallation, except that damaged, cracked or broken slate or tile shall not be reinstalled. Existing vent flashing, metal edgings, drain outlets, collars and metal counterflashings shall not be reinstalled where rusted, damaged or deteriorated. Aggregate surfacing materials shall not be reinstalled.
Flashings shall be reconstructed in accordance with approved manufacturer's installation instructions. Metal flashing to which bituminous materials are to be adhered shall be primed prior to installation.
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