International Building Code Section 2603


International Building Code 2603.1

General. The provisions of this section shall govern the
requirements and uses of foam plastic insulation in buildings
and structures.

International Building Code 2603.2

Labeling and identification. Packages and containers
of foam plastic insulation and foam plastic insulation components
delivered to the job site shall bear the label of an approved
agency showing the manufacturer’s name, the product listing,
product identification and information sufficient to determine
that the end use will comply with the code requirements.

International Building Code 2603.3

Surface-burning characteristics. Unless otherwise
indicated in this section, foam plastic insulation and foam plastic
cores of manufactured assemblies shall have a flame spread
index of not more than 75 and a smoke-developed index of not
more than 450 where tested in the maximum thickness
intended for use in accordance with ASTM E 84. Loose
fill-type foam plastic insulation shall be tested as board stock
for the flame spread index and smoke-developed index.
Exceptions:
1. Smoke-developed index for interior trim as provided
for in Section 2604.2.
2. In cold storage buildings, ice plants, food plants, food
processing rooms and similar areas, foam plastic
insulation where tested in a thickness of 4 inches (102
mm) shall be permitted in a thickness up to 10 inches
(254 mm) where the building is equipped throughout
with an automatic fire sprinkler system in accordance
with Section 903.3.1.1. The approved automatic
sprinkler system shall be provided in both the room
and that part of the building in which the room is
located.
3. 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. The smoke-developed index
shall not be limited for roof applications.
4. Foam plastic insulation greater than 4 inches (102
mm) in thickness shall have a maximum flame spread
index of 75 and a smoke-developed index of 450
where tested at a minimum thickness of 4 inches (102
mm), provided the end use is approved in accordance
with Section 2603.9 using the thickness and density
intended for use.
5. Flame spread and smoke-developed indexes for foam
plastic interior signs in covered mall buildings provided
the signs comply with Section 402.15.

International Building Code 2603.4

Thermal barrier. 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 0.5-inch
(12.7 mm) gypsum wallboard or equivalent thermal barrier
2006 INTERNATIONAL BUILDING CODE. 507
material that will limit the average temperature rise of the unexposed
surface to not more than 2500F (1200C) after 15 minutes
of fire exposure, complying with the standard time-temperature
curve of ASTM E 119. 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.

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.

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.

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 6000F and 8000F (3160C and
4270C), 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.
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.

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.

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.

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,BorCroof-covering
assembly, provided the assembly with the foam
plastic insulation satisfactorily passes FM 4450 or UL
1256.

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 1.5-inch-thick (38 mm) mineral fiber insulation;
0.25-inch-thick (6.4 mm) wood structural panel,
particleboard or hardboard; 0.375-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.

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.

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.

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.

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 0.5 inch (12.7 mm), provided
it is separated from the interior of the building by
508 2006 INTERNATIONAL BUILDING CODE.
PLASTIC
not less than 2 inches (51 mm) of mineral fiber insulation
or equivalent or where applied as insulation with
re-siding over existing wall construction.

Interior trim. Foam plastic used as interior
trim in accordance with Section 2604 shall be permitted
without a thermal barrier.

Interior signs. Foam plastic used for interior
signs in covered mall buildings in accordance with
Section 402.15 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.

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.

International Building Code 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.

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.

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 6000F and 8000F (3160C and
4270C), 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.
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.

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.

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.

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,BorCroof-covering
assembly, provided the assembly with the foam
plastic insulation satisfactorily passes FM 4450 or UL
1256.

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 1.5-inch-thick (38 mm) mineral fiber insulation;
0.25-inch-thick (6.4 mm) wood structural panel,
particleboard or hardboard; 0.375-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.

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.

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.

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.

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 0.5 inch (12.7 mm), provided
it is separated from the interior of the building by
508 2006 INTERNATIONAL BUILDING CODE.
PLASTIC
not less than 2 inches (51 mm) of mineral fiber insulation
or equivalent or where applied as insulation with
re-siding over existing wall construction.

Interior trim. Foam plastic used as interior
trim in accordance with Section 2604 shall be permitted
without a thermal barrier.

Interior signs. Foam plastic used for interior
signs in covered mall buildings in accordance with
Section 402.15 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.

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.

International Building Code 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.

International Building Code 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 0.5 inch (12.7 mm), provided
it is separated from the interior of the building by
508 2006 INTERNATIONAL BUILDING CODE.
PLASTIC
not less than 2 inches (51 mm) of mineral fiber insulation
or equivalent or where applied as insulation with
re-siding over existing wall construction.

International Building Code 2603.4.1.11

Interior trim. Foam plastic used as interior
trim in accordance with Section 2604 shall be permitted
without a thermal barrier.

International Building Code 2603.4.1.12

Interior signs. Foam plastic used for interior
signs in covered mall buildings in accordance with
Section 402.15 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.

International Building 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.

International Building Code 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 6000F and 8000F (3160C and
4270C), 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.
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.

International Building Code 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.

International Building Code 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.

International Building Code 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,BorCroof-covering
assembly, provided the assembly with the foam
plastic insulation satisfactorily passes FM 4450 or UL
1256.

International Building Code 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 1.5-inch-thick (38 mm) mineral fiber insulation;
0.25-inch-thick (6.4 mm) wood structural panel,
particleboard or hardboard; 0.375-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.

International Building Code 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.

International Building Code 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.

International Building Code 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.

International Building Code 2603.5

Exterior walls of buildings of any height. Exterior
walls of buildings of Type I, II, III or IV construction of any
height shall comply with Sections 2603.5.1 through 2603.5.7.
Exterior walls of cold storage buildings required to be constructed
of noncombustible materials, where the building is
more than one story in height, shall also comply with the provisions
of Sections 2603.5.1 through 2603.5.7. Exterior walls of
buildings of Type V construction shall comply with Sections
2603.2, 2603.3 and 2603.4.

Fire-resistance-rated walls. Where the wall is
required to have a fire-resistance rating, data based on tests
conducted in accordance with ASTM E 119 shall be provided
to substantiate that the fire-resistance rating is maintained.

Thermal barrier. Any foam plastic insulation
shall be separated from the building interior by a thermal
barrier meeting the provisions of Section 2603.4, unless
special approval is obtained on the basis of Section 2603.8.
Exception: One-story buildings complying with Section
2603.4.1.4.

Potential heat. The potential heat of foam plastic
insulation in any portion of the wall or panel shall not
exceed the potential heat expressed in Btu per square feet
(mJ/m2) of the foam plastic insulation contained in the wall
assembly tested in accordance with Section 2603.5.5. The
potential heat of the foam plastic insulation shall be determined
by tests conducted in accordance with NFPA259 and
the results shall be expressed in Btu per square feet (mJ/m2).
Exception: One-story buildings complying with Section
2603.4.1.4.

Flame spread and smoke-developed indexes.
Foam plastic insulation, exterior coatings and facings shall
be tested separately in the thickness intended for use, but not
to exceed 4 inches (102 mm), and shall each have a flame
spread index of 25 or less and a smoke-developed index of
450 or less as determined in accordance withASTME84.
Exception: Prefabricated or factory-manufactured panels
having minimum 0.020-inch (0.51 mm) aluminum
facings and a total thickness of 0.25 inch (6.4 mm) or less
are permitted to be tested as an assembly where the foam
plastic core is not exposed in the course of construction.

Test standard. The wall assembly shall be tested
in accordance with and comply with the acceptance criteria
of NFPA 285.
Exception: One-story buildings complying with Section
2603.4.1.4.

Label required. The edge or face of each piece of
foam plastic insulation shall bear the label of an approved
agency. The label shall contain the manufacturer�s or distributor�s
identification, model number, serial number or
definitive information describing the product or materials�
performance characteristics and approved agency�s identification.

Ignition. Exteriorwalls shall not exhibit sustained
flaming where tested in accordance with NFPA 268. Where
a material is intended to be installed in more than one thickness,
tests of the minimum and maximum thickness
intended for use shall be performed.
Exception: Assemblies protected on the outside with
one of the following:
1. Athermal barrier complying with Section 2603.4.
2. A minimum 1 inch (25 mm) thickness of concrete
or masonry.
3. Glass-fiber-reinforced concrete panels of a minimum
thickness of 0.375 inch (9.5 mm).
4. Metal-faced panels having minimum 0.019-
inch-thick (0.48 mm) aluminum or 0.016-inchthick
(0.41 mm)corrosion-resistant steel outer facings.
5. A minimum 0.875 inch (22.2 mm) thickness of
stucco complying with Section 2510.

International Building Code 2603.5.1

Fire-resistance-rated walls. Where the wall is
required to have a fire-resistance rating, data based on tests
conducted in accordance with ASTM E 119 shall be provided
to substantiate that the fire-resistance rating is maintained.

International Building Code 2603.5.2

Thermal barrier. Any foam plastic insulation
shall be separated from the building interior by a thermal
barrier meeting the provisions of Section 2603.4, unless
special approval is obtained on the basis of Section 2603.8.
Exception: One-story buildings complying with Section
2603.4.1.4.

International Building Code 2603.5.3

Potential heat. The potential heat of foam plastic
insulation in any portion of the wall or panel shall not
exceed the potential heat expressed in Btu per square feet
(mJ/m2) of the foam plastic insulation contained in the wall
assembly tested in accordance with Section 2603.5.5. The
potential heat of the foam plastic insulation shall be determined
by tests conducted in accordance with NFPA259 and
the results shall be expressed in Btu per square feet (mJ/m2).
Exception: One-story buildings complying with Section
2603.4.1.4.

International Building Code 2603.5.4

Flame spread and smoke-developed indexes.
Foam plastic insulation, exterior coatings and facings shall
be tested separately in the thickness intended for use, but not
to exceed 4 inches (102 mm), and shall each have a flame
spread index of 25 or less and a smoke-developed index of
450 or less as determined in accordance withASTME84.
Exception: Prefabricated or factory-manufactured panels
having minimum 0.020-inch (0.51 mm) aluminum
facings and a total thickness of 0.25 inch (6.4 mm) or less
are permitted to be tested as an assembly where the foam
plastic core is not exposed in the course of construction.

International Building Code 2603.5.5

Test standard. The wall assembly shall be tested
in accordance with and comply with the acceptance criteria
of NFPA 285.
Exception: One-story buildings complying with Section
2603.4.1.4.

International Building Code 2603.5.6

Label required. The edge or face of each piece of
foam plastic insulation shall bear the label of an approved
agency. The label shall contain the manufacturer�s or distributor�s
identification, model number, serial number or
definitive information describing the product or materials�
performance characteristics and approved agency�s identification.

International Building Code 2603.5.7

Ignition. Exteriorwalls shall not exhibit sustained
flaming where tested in accordance with NFPA 268. Where
a material is intended to be installed in more than one thickness,
tests of the minimum and maximum thickness
intended for use shall be performed.
Exception: Assemblies protected on the outside with
one of the following:
1. Athermal barrier complying with Section 2603.4.
2. A minimum 1 inch (25 mm) thickness of concrete
or masonry.
3. Glass-fiber-reinforced concrete panels of a minimum
thickness of 0.375 inch (9.5 mm).
4. Metal-faced panels having minimum 0.019-
inch-thick (0.48 mm) aluminum or 0.016-inchthick
(0.41 mm)corrosion-resistant steel outer facings.
5. A minimum 0.875 inch (22.2 mm) thickness of
stucco complying with Section 2510.

International Building Code 2603.6

Roofing. Foam plastic insulation meeting the requirements
of Sections 2603.2, 2603.3 and 2603.4 shall be permitted
as part of a roof-covering assembly, provided the assembly
with the foam plastic insulation is a Class A, B or C roofing
assembly where tested in accordance with ASTM E 108 or UL
790.

International Building Code 2603.7

Plenums. Foam plastic insulation shall not be used as
interior wall or ceiling finish in plenums except as permitted in
Section 2604 or when protected by a thermal barrier in accordance
with Section 2603.4.

International Building Code 2603.8

Protection against termites. In areas where the probability
of termite infestation is very heavy in accordance with
Figure 2603.8, extruded and expanded polystyrene,
polyisocyanurate and other foam plastics shall not be installed
on the exterior face or under interior or exterior foundation
walls or slab foundations located below grade. The clearance
2006 INTERNATIONAL BUILDING CODE. 509
PLASTIC
between foam plastics installed above grade and exposed earth
shall be at least 6 inches (152 mm).
Exceptions:
1. Buildings where the structural members of walls,
floors, ceil ings and roofs are entirely of
noncombustible materials or preservatively treated
wood.
2. An approved method of protecting the foam plastic
and structure from subterranean termite damage is
provided.
3. On the interior side of basement walls.

International Building Code 2603.9

Special approval. Foam plastic shall not be required to
comply with the requirements of Sections 2603.4 through
2603.7 where specifically approved based on large-scale tests
such as, but not limited to, NFPA 286 (with the acceptance criteria
of Section 803.2), FM 4880, UL 1040 or UL 1715. Such
testing shall be related to the actual end-use configuration and
be performed on the finished manufactured foam plastic
assembly in the maximum thickness intended for use. Foam
plastics that are used as interior finish on the basis of special
tests shall also conform to the flame spread requirements of
Chapter 8. Assemblies tested shall include seams, joints and
other typical details used in the installation of the assembly and
shall be tested in the manner intended for use.