780 CMR 15.00 ROOF ASSEMBLIES AND ROOFTOP STRUCTURES 780 CMR 1501.0 GENERAL ering and the roof deck. A roof assembly includes 1501.1 Scope. The provisions of 780 CMR 15.00 the roof deck, vapor retarder, substrate or thermal shall govern the design, materials, construction and barrier, insulation, vapor retarder and roof covering. quality of roof assemblies, and rooftop structures. ROOF COVERING. The covering applied to the roof deck for weather resistance, fire classification or 780 CMR 1502.0 DEFINITIONS appearance. 1502.1 General. The following words and terms shall, for the purposes of 780 CMR 15.00 and as ROOF COVERING SYSTEM. See “Roof used elsewhere in 780 CMR, have the meanings assembly.” shown in 780 CMR 1502.0 ROOF DECK. The flat or sloped surface not in- BUILT-UP ROOF COVERING. Two or more cluding its supporting members or vertical supports. layers of felt cemented together and surfaced with a ROOF RECOVER. The process of installing an cap sheet, mineral aggregate, smooth coating or additional roof covering over a prepared existing similar surfacing material. roof covering without removing the existing roof INTERLAYMENT. A layer of felt or covering. nonbituminous saturated felt not less than 18 inches ROOF REPAIR. Reconstruction or renewal of any (457 mm) wide, shingled between each course of a part of an existing roof for the purposes of its wood-shake roof covering. maintenance. MECHANICAL EQUIPMENT SCREEN. A ROOF REPLACEMENT. The process of partially enclosed rooftop structure used to removing the existing roof covering, repairing any aesthetically conceal heating, ventilating and air damaged substrate and installing a new roof conditioning (HVAC) electrical or mechanical covering. equipment from view. ROOF VENTILATION. The natural or METAL ROOF PANEL. An interlocking metal mechanical process of supplying conditioned or sheet having a minimum installed weather exposure unconditioned air to, or removing such air from, of three square feet (.279 m2) per sheet. attics, cathedral ceilings or other enclosed spaces METAL ROOF SHINGLE. An interlocking metal over which a roof assembly is installed. sheet having an installed weather exposure less than ROOFTOP STRUCTURE. An enclosed structure three square feet (.279 m2) per sheet. on or above the roof of any part of a building. MODIFIED BITUMEN ROOF COVERING. SCUPPER. An opening in a wall or parapet that One or more layers of polymer-modified asphalt allows water to drain from a roof. sheets. The sheet materials shall be fully adhered or mechanically attached to the substrate or held in SINGLE-PLY MEMBRANE. A roofing place with an approved ballast layer. membrane that is field applied using one layer of membrane material (either homogeneous or PENTHOUSE. An enclosed, unoccupied structure composite) rather than multiple layers. above the roof of a building, other than a tank, tower, spire, dome cupola or bulkhead, occupying UNDERLAYMENT. One or more layers of felt, not more than one-third of the roof area. sheathing paper, nonbituminous saturated felt or other approved material over which a steep-slope POSITIVE ROOF DRAINAGE. The drainage roof covering is applied. condition in which consideration has been made for all loading deflections of the roof deck, and 780 CMR 1503.0 WEATHER PROTECTION additional slope has been provided to ensure 1503.1 General. Roof decks shall be covered with drainage of the roof within 48 hours of precipitation. approved roof coverings secured to the building or REROOFING. The process of recovering or structure in accordance with the provisions of replacing an existing roof covering. See “Roof 780 CMR 15.00. Roof coverings shall be designed, recover” and “Roof replacement.” installed and maintained in accordance with 780 CMR and the approved manufacturer’s ROOF ASSEMBLY. A system designed to provide instructions such that the roof covering shall serve to weather protection and resistance to design loads. protect the building or structure. The system consists of a roof covering and roof deck or a single component serving as both the roof cov- 8/22/08 (Effective 9/1/08) 780 CMR - Seventh Edition 363 780 CMR: STATE BOARD OF BUILDING REGULATIONS AND STANDARDS THE MASSACHUSETTS STATE BUILDING CODE 1503.2 Flashing. Flashing shall be installed in such 1504.3.2 Metal Panel Roof Systems. Metal a manner so as to prevent moisture entering the wall panel roof systems through fastened or standing and roof through joints in copings, through moisture- seam shall be tested in accordance with UL 580 or permeable materials and at intersections with parapet ASTM E 1592. walls and other penetrations through the roof plane. 1504.4 Ballasted Low-slope Roof Systems. 1503.2.1 Locations. Flashing shall be installed at Ballasted low-slope (roof slope < 2:12) single-ply wall and roof intersections, at gutters, wherever roof system coverings installed in accordance with there is a change in roof slope or direction and 780 CMR 1507.0 shall be designed in accordance around roof openings. Where flashing is of metal, with ANSI/SPRI RP-4. the metal shall be corrosion resistant with a thickness of not less than 0.019 inch (.483 mm) 1504.5 Edge Securement for Low-slope Roofs. (No. 26 galvanized sheet). Low-slope membrane roof systems metal edge securement, except gutters, installed in accordance 1503.3 Coping. Parapet walls shall be properly with 780 CMR 1507, shall be designed in coped with noncombustible, weatherproof materials accordance with ANSI/SPRI ES-1, except the basic of a width no less than the thickness of the parapet wind speed shall be determined from Figure 1609. wall. 1504.6 Physical Properties. Roof coverings [P] 1503.4 Roof Drainage. Design and installation installed on low-slope roofs (roof slope < 2:12) in of roof drainage systems shall comply with accordance with 780 CMR 1507 shall demonstrate 248 CMR. physical integrity over the working life of the roof 1503.4.1 Gutters. Gutters and leaders placed on based upon 2,000 hours of exposure to accelerated the outside of buildings, other than Group R-3 as weathering tests conducted in accordance with applicable in 780 CMR 120.Z, private garages and ASTM G 152, ASTM G 155 or ASTM G 154. buildings of Type V construction, shall be of Those roof coverings that are subject to cyclical noncombustible material or a minimum of flexural response due to wind loads shall not Schedule 40 plastic pipe. demonstrate any significant loss of tensile strength for unreinforced membranes or breaking strength for 1503.5 Roof Ventilation. Intake and exhaust vents reinforced membranes when tested as required. shall be provided in accordance with 780 CMR 1203.2 and the manufacturer’s installation 1504.7 Impact resistance. Roof coverings installed instructions. on low-slope roofs (roof slope < 2:12) in accordance with 780 CMR 1507 shall resist impact damage 780 CMR 1504.0 PERFORMANCE based on the results of tests conducted in accordance REQUIREMENTS with ASTM D 3746, ASTM D 4272, CGSB 37-GP- 52M or FM 4470. 1504.1 Wind Resistance of Roofs. Roof decks and roof coverings shall be designed for wind loads in accordance with 780 CMR 16.00 and 780 CMR 780 CMR 1505.0 FIRE CLASSIFICATION 1504.2, 1504.3 and 1504.4. 1505.1 General. Roof assemblies shall be divided 1504.1.1 Wind Resistance of Asphalt Shingles. into the classes defined below. Class A, B and C Asphalt shingles shall be designed for wind roof assemblies and roof coverings required to be speeds in accordance with 780 CMR 1507.2.7. listed by 780 CMR 1505.0 shall be tested in accordance with ASTM E 108 or UL 790. In 1504.2 Wind Resistance of Clay and Concrete addition, fire-retardant-treated wood roof coverings Tile. Clay and concrete tile roof coverings shall be shall be tested in accordance with ASTM D 2898. connected to the roof deck in accordance with The minimum roof coverings installed on buildings 780 CMR 16.00. shall comply with Table 1505.1 based on the type of 1504.3 Wind Resistance of Nonballasted Roofs. construction of the building. Roof coverings installed on roofs in accordance with a,b 780 CMR 1507 that are mechanically attached or TABLE 1505.1 MINIMUM ROOF adhered to the roof deck shall be designed to resist COVERING CLASSIFICATION FOR the design wind load pressures for cladding in TYPES OF CONSTRUCTION IA IB IIA IIB IIIA IIIB IV VA VB 780 CMR 16.00. BBBCccBC BBCc 1504.3.1 Other Roof Systems. Roof systems For SI: 1 foot = 304.8 mm, 1 square foot = 0.0929 m2. with built-up, modified bitumen, fully adhered or a. Unless otherwise required in accordance with the mechanically attached single-ply through fastened International Urban Wildland Interface Code or due metal panel roof systems, and other types of to the location of the building within a fire district in membrane roof coverings shall also be tested in accordance with Appendix D. accordance with FM 4450, FM 4470, UL 580 or b. Non-classified roof coverings shall be permitted on UL 1897. buildings of Group R-3, as applicable in 780 CMR 120.Z, and Group U occupancies, where there is a 364 780 CMR - Seventh Edition 8/22/08 (Effective 9/1/08) 780 CMR: STATE BOARD OF BUILDING REGULATIONS AND STANDARDS ROOF ASSEMBLIES AND ROOFTOP STRUCTURES minimum fire-separation distance of 6 feet measured underlayment of 0.625-inch (15.9 mm) Type X from the leading edge of the roof. water-resistant gypsum backing board or gypsum c. Buildings that are not more than two stories in height sheathing shall be placed under minimum nominal and having not more than 6,000 square feet of 0.5-inch-thick (12.7 mm) wood structural panel solid projected roof area and where there is a minimum sheathing or one-inch (25 mm) nominal spaced ten-foot fire-separation distance from the leading edge sheathing.