2003 International Building Code® 253
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Color profile: Generic CMYK printer profile Composite Default screen CHAPTER 15 ROOF ASSEMBLIES AND ROOFTOP STRUCTURES ROOF COVERING. The covering applied to the roof deck SECTION 1501 for weather resistance, fire classification or appearance. GENERAL 1501.1 Scope. The provisions of this chapter shall govern the ROOF COVERING SYSTEM. See “Roof assembly.” design, materials, construction and quality of roof assemblies, ROOF DECK. The flat or sloped surface not including its sup- and rooftop structures. porting members or vertical supports. ROOF RECOVER. The process of installing an additional roof covering over a prepared existing roof covering without SECTION 1502 removing the existing roof covering. DEFINITIONS 1502.1 General. The following words and terms shall, for the ROOF REPAIR. Reconstruction or renewal of any part of an purposes of this chapter and as used elsewhere in this code, existing roof for the purposes of its maintenance. have the meanings shown herein. ROOF REPLACEMENT. The process of removing the exist- BUILT-UP ROOF COVERING. Two or more layers of felt ing roof covering, repairing any damaged substrate and install- cemented together and surfaced with a cap sheet, mineral ag- ing a new roof covering. gregate, smooth coating or similar surfacing material. ➡ ROOF VENTILATION. The natural or mechanical process INTERLAYMENT. A layer of felt or nonbituminous satu- of supplying conditioned or unconditioned air to, or removing rated felt not less than 18 inches (457 mm) wide, shingled be- such air from, attics, cathedral ceilings or other enclosed tween each course of a wood-shake roof covering. spaces over which a roof assembly is installed. MECHANICAL EQUIPMENT SCREEN. A partially en- ROOFTOP STRUCTURE. An enclosed structure on or closed rooftop structure used to aesthetically conceal heating, above the roof of any part of a building. ventilating and air conditioning (HVAC) electrical or mechani- SCUPPER. An opening in a wall or parapet that allows water cal equipment from view. to drain from a roof. METAL ROOF PANEL. An interlocking metal sheet having a 2 SINGLE-PLY MEMBRANE. A roofing membrane that is minimum installed weather exposure of 3 square feet (.279 m ) field applied using one layer of membrane material (either ho- per sheet. mogeneous or composite) rather than multiple layers. METAL ROOF SHINGLE. An interlocking metal sheet hav- UNDERLAYMENT. One or more layers of felt, sheathing pa- ing an installed weather exposure less than 3 square feet (.279 2 per, nonbituminous saturated felt or other approved material m ) per sheet. over which a steep-slope roof covering is applied. 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 SECTION 1503 or held in place with an approved ballast layer. WEATHER PROTECTION PENTHOUSE. An enclosed, unoccupied structure above the 1503.1 General. Roof decks shall be covered with approved roof of a building, other than a tank, tower, spire, dome cupola roof coverings secured to the building or structure in accor- or bulkhead, occupying not more than one-third of the roof dance with the provisions of this chapter. Roof coverings shall area. be designed, installed and maintained in accordance with this POSITIVE ROOF DRAINAGE. The drainage condition in code and the approved manufacturer’s instructions such that which consideration has been made for all loading deflections the roof covering shall serve to protect the building or structure. of the roof deck, and additional slope has been provided to en- 1503.2 Flashing. Flashing shall be installed in such a manner sure drainage of the roof within 48 hours of precipitation. so as to prevent moisture entering the wall and roof through REROOFING. The process of recovering or replacing an ex- joints in copings, through moisture-permeable materials and at isting roof covering. See “Roof recover” and “Roof replace- intersections with parapet walls and other penetrations through ment.” the roof plane. ROOF ASSEMBLY. A system designed to provide weather 1503.2.1 Locations. Flashing shall be installed at wall and protection and resistance to design loads. The system consists roof intersections, at gutters, wherever there is a change in of a roof covering and roof deck or a single component serving roof slope or direction and around roof openings. Where as both the roof covering and the roof deck. A roof assembly in- flashing is of metal, the metal shall be corrosion resistant cludes the roof deck, vapor retarder, substrate or thermal bar- with a thickness of not less than 0.019 inch (.483 mm) (No. rier, insulation, vapor retarder and roof covering. 26 galvanized sheet). 2003 INTERNATIONAL BUILDING CODE® 253 15_Phoenix_IBC_2005_PG253.pS M:\data\CODES\STATE CODES\Phoenix\2005\Replacement pages\Building Code\Final VP\15_Phoenix_IBC_2005.vpFinal Friday, July 15, 2005 8:45:42 AM Color profile: Generic CMYK printer profile Composite Default screen ROOF ASSEMBLIES AND ROOFTOP STRUCTURES 1503.3 Coping. Parapet walls shall be properly coped with 1504.2 Wind resistance of clay and concrete tile. Clay and noncombustible, weatherproof materials of a width no less concrete tile roof coverings shall be connected to the roof deck than the thickness of the parapet wall. in accordance with Chapter 16. 1503.4 Roof drainage. Design and installation of roof drain- 1504.3 Wind resistance of nonballasted roofs. Roof cover- age systems shall comply with this section and the Arizona ings installed on roofs in accordance with Section 1507 that are State Plumbing Code. mechanically attached or adhered to the roof deck shall be de- signed to resist the design wind load pressures for cladding in 1503.4.1 Primary roof drainage systems. A primary roof Chapter 16. drainage system shall be provided. 1503.4.1.1 Design. The design rainfall rate (inches per 1504.3.1 Other roof systems. Roof systems with built-up, hour) shall be not less than 6 inches (152 mm) per hour. modified bitumen, fully adhered or mechanically attached single-ply through fastened metal panel roof systems, and 1503.4.2 Secondary roof drainage systems. A secondary other types of membrane roof coverings shall also be tested roof drainage system shall be provided, as follows: in accordance with FM 4450, FM 4470, UL 580 or UL 1897. 1. The design rainfall rate (inches per hour) shall be not 1504.3.2 Metal panel roof systems. Metal panel roof sys- less than 6 inches (152 mm) per hour. tems through fastened or standing seam shall be tested in ac- 2. The secondary drainage system shall be completely cordance with UL 580 or ASTM E 1592. independent of the primary roof drainage system. 1504.4 Ballasted low-slope roof systems. Ballasted low-slope 3. The roof design load shall include the weight of rain- (roof slope < 2:12) single-ply roof system coverings installed water up to the height above the drainage inlet that is in accordance with Section 1507 shall be designed in accor- required to achieve the secondary drainage design ca- dance with ANSI/SPRI RP-4. pacity, taking into consideration potential ponding re- sulting from roof deflection. 1504.5 Edge securement for low-slope roofs. Low-slope membrane roof systems metal edge securement, except gutters, 4. Where wall scuppers or interior drains are used for installed in accordance with Section 1507, shall be designed in secondary drainage, the base of the secondary drain- accordance with ANSI/SPRI ES-1, except the basic wind age inlets shall be a maximum of 2 inches (51 mm) speed shall be determined from Figure 1609. above the base of the primary drainage inlets with a minimum separation of 12 inches (305 mm). 1504.6 Physical properties. Roof coverings installed on < 5. Scuppers shall have a minimum opening width of 6 low-slope roofs (roof slope 2:12) in accordance with Section inches (152 mm) or three times the diameter of the 1507 shall demonstrate physical integrity over the working life calculated roof drain diameter, whichever is greater of the roof based upon 2,000 hours of exposure to accelerated and a minimum open height of 6 inches (152 mm). weathering tests conducted in accordance with ASTM G 152, The minimum height of the scuppers serving areas ASTM G 155 or ASTM G 154. Those roof coverings that are that may be occupied (sunroofs, balconies and decks) subject to cyclical flexural response due to wind loads shall not shall be 4 inches (102 mm). demonstrate any significant loss of tensile strength for unreinforced membranes or breaking strength for reinforced 1503.4.3 Gutters. Gutters and leaders placed on the outside membranes when tested as herein required. of buildings, other than Group R-3 as applicable in Section 101.2, private garages and buildings of Type V construc- 1504.7 Impact resistance. Roof coverings installed on tion, shall be of noncombustible material or a minimum of low-slope roofs (roof slope < 2:12) in accordance with Section Schedule 40 plastic pipe. 1507 shall resist impact damage based on the results of tests conducted in accordance with ASTM D 3746, ASTM D 4272, 1503.5 Roof ventilation. Intake and exhaust vents shall be pro- CGSB 37-GP-52M or FM 4470. vided in accordance with Section 1203.2 and the manufac- turer’s installation instructions. SECTION 1505 FIRE CLASSIFICATION SECTION 1504 PERFORMANCE REQUIREMENTS 1505.1 General. Roof assemblies shall be divided into the 1504.1 Wind resistance of roofs. Roof decks and roof cover- classes defined below. Class A, B and C roof assemblies and ings shall be designed for wind loads in accordance with Chap- roof coverings required to be listed by this section shall be ter 16 and Sections 1504.2, 1504.3 and 1504.4. tested in accordance with ASTM E 108 or UL 790.