Code of Massachusetts Regulations › 780 CMR - STATE BOARD OF BUILDING REGULATIONS AND STANDARDS › Chapter 26 - Plastic › Section 2603 - FOAM PLASTIC INSULATION › Subsection 2603.4 - Thermal barrier

Current through Register 1525, July 5, 2024
Except as provided for in Sections 2603.4.1 and 2603.9, foam
				  plastic shall be separated from the interior of a building by an approved
				  thermal barrier of 1/2-inch
				  (12.7 mm) gypsum wallboard or equivalent thermal barrier material that will
				  limit the average temperature rise of the unexposed surface to not more than
				  250°F (120°C) after 15 minutes of fire exposure, complying with the
				  standard time-temperature curve of ASTM E 119 or UL 263. The thermal barrier
				  shall be installed in such a manner that it will remain in place for 15 minutes
				  based on FM 4880, UL 1040, NFPA 286 or UL 1715. Combustible concealed spaces
				  shall comply with Section 717.
2603.4.1
Thermal barrier not
				required.
The thermal barrier specified in Section 2603.4 is not
				required under the conditions set forth in Sections 2603.4.1.1 through
				2603.4.1.13.
2603.4.1.1
Masonry or
				concrete construction.
A thermal barrier is not required for foam
				plastic installed in a masonry or concrete wall, floor or roof system where the
				foam plastic insulation is covered on each face by a minimum of 1 inch (25 mm)
				thickness of masonry or concrete.
2603.4.1.2
Cooler and freezer
				walls.
Foam plastic installed in a maximum thickness of 10 inches (254
				mm) in cooler and freezer walls shall:
1. Have
				a flame spread index of 25 or less and a smoke-developed index of not more than
				450, where tested in a minimum 4 inch (102 mm) thickness.
2. Have flash ignition and self-ignition
				temperatures of not less than 600°F and 800°F (316°C and
				427°C), respectively.
3. Have a
				covering of not less than 0.032-inch (0.8 mm) aluminum or corrosion-resistant
				steel having a base metal thickness not less than 0.0160 inch (0.4 mm) at any
				point.
4. Be protected by an
automatic sprinkler system
in accordance with Section
				903.3.1.1. Where the cooler or freezer is within a building, both the cooler or
				freezer and that part of the building in which it is located shall be
				sprinklered.
2603.4.1.3
Walk-in coolers.
In nonsprinklered buildings, foam plastic having
				a thickness that does not exceed 4 inches (102 mm) and a maximum flame spread
				index of 75 is permitted in walk-in coolers or freezer units where the
				aggregate floor area does not exceed 400 square feet (37
				m2) and the foam plastic is covered by a metal
				facing not less than 0.032-inch-thick (0.81 mm) aluminum or corrosion-resistant
				steel having a minimum base metal thickness of 0.016 inch (0.41 mm). A
				thickness of up to 10 inches (254 mm) is permitted where protected by a thermal
				barrier.
2603.4.1.4
Exterior
				walls-one-story buildings.
For one-
story
buildings,
				foam plastic having a flame spread index of 25 or less, and a smoke-developed
				index of not more than 450, shall be permitted without thermal barriers in or
				on
exterior walls
in a thickness not more than 4 inches (102
				mm) where the foam plastic is covered by a thickness of not less than
				0.032-inch-thick (0.81 mm) aluminum or corrosion-resistant steel having a base
				metal thickness of 0.0160 inch (0.41 mm) and the building is equipped
				throughout with an
automatic sprinkler system
in accordance
				with Section 903.3.1.1.
2603.4.1.5
Roofing.
Foam plastic insulation under a roof assembly or roof
				covering that is installed in accordance with the code and the manufacturer's
				instructions shall be separated from the interior of the building by wood
				structural panel sheathing not less than 0.47 inch (11.9 mm) in thickness
				bonded with exterior glue, with edges supported by blocking, tongue-and-groove
				joints or other approved type of edge support, or an equivalent material. A
				thermal barrier is not required for foam plastic insulation that is a part of a
				Class A, B or C roof-covering assembly, provided the assembly with the foam
				plastic insulation satisfactorily passes FM 4450 or UL 1256.
2603.4.1.6
Attics and crawl
				spaces.
Within an
attic
or crawl space where entry is
				made only for service of utilities, foam plastic insulation shall be protected
				against ignition by
				11/2-inch-thick (38 mm)
				mineral fiber insulation;
				1/4-inch-thick (6.4 mm) wood
				structural panel, particleboard or hardboard;
				3/8-inch (9.5 mm) gypsum
				wallboard, corrosion-resistant steel having a base metal thickness of 0.016
				inch (0.4 mm) or other approved material installed in such a manner that the
				foam plastic insulation is not exposed. The protective covering shall be
				consistent with the requirements for the type of construction.
2603.4.1.7
Doors not required to have a
				fire protection rating.
Where pivoted or side-hinged doors are permitted
				without a fire protection rating, foam plastic insulation, having a flame
				spread index of 75 or less and a smoke-developed index of not more than 450,
				shall be permitted as a core material where the door facing is of metal having
				a minimum thickness of 0.032-inch (0.8 mm) aluminum or steel having a base
				metal thickness of not less than 0.016 inch (0.4 mm) at any point.
2603.4.1.8
Exterior doors in buildings
				of Group R-2 or R-3.
In occupancies classified as Group R-2 or R-3,
				foam-filled exterior entrance doors to individual
dwelling
				units
that do not require a fire-resistance rating shall be faced with
				wood or other approved materials.
2603.4.1.9
Garage doors.
Where
				garage doors are permitted without a fire-resistance rating and foam plastic is
				used as a core material, the door facing shall be metal having a minimum
				thickness of 0.032-inch (0.8 mm) aluminum or 0.010-inch (0.25 mm) steel or the
				facing shall be minimum 0.125-inch-thick (3.2 mm) wood. Garage doors having
				facings other than those described above shall be tested in accordance with,
				and meet the acceptance criteria of, DASMA 107.
Exception:
Garage doors using foam plastic
				  insulation complying with Section 2603.3 in detached and attached garages
				  associated with one- and two-family dwellings need not be provided with a
				  thermal barrier.
2603.4.1.10
Siding backer board.
Foam plastic insulation of not more than 2,000 British thermal units per square
				feet (Btu/sq. ft.) (22.7 mJ/m2) as determined by
				NFPA 259 shall be permitted as a siding backer board with a maximum thickness
				of 1/2 inch (12.7 mm),
				provided it is separated from the interior of the building by not less than 2
				inches (51 mm) of mineral fiber insulation or equivalent or where applied as
				insulation with residing over existing wall construction.
2603.4.1.11
Interior trim.
Foam
				plastic used as interior
trim
in accordance with Section 2604
				shall be permitted without a thermal barrier.
2603.4.1.12
Interior signs.
Foam
				plastic used for interior signs in
covered mall buildings
in
				accordance with Section 402.16 shall be permitted without a thermal barrier.
				Foam plastic signs that are not affixed to interior building surfaces shall
				comply with Chapter 8 of the
International Fire
				Code
.
2603.4.1.13
Type V construction.
Foam plastic spray applied to a sill plate and
				header of Type V construction is subject to all of the following:
1. The maximum thickness of the foam plastic
				shall be 31/4 inches (82.6
				mm).
2. The density of the foam
				plastic shall be in the range of 1.5 to 2.0 pcf (24 to 32
				kg/m3).
3. The foam plastic shall have a flame spread
				index of 25 or less and an accompanying smoke-developed index of 450 or less
				when tested in accordance with ASTM E 84 or UL 723.