International Building Code Section 2508


International Building Code 2508.1

General. Gypsum board and gypsum plaster construction
shall be of the materials listed in Tables 2506.2 and 2507.2.
These materials shall be assembled and installed in compliance
with the appropriate standards listed in Tables 2508.1 and
2511.1, and Chapter 35.

International Building Code 2508.2

Limitations. Gypsum wallboard or gypsum plaster
shall not be used in any exterior surface where such gypsum
construction will be exposed directly to the weather. Gypsum
wallboard shall not be used where there will be direct exposure
to water or continuous high humidity conditions. Gypsum
sheathing shall be installed on exterior surfaces in accordance
with ASTM C 1280.

Weather protection. Gypsumwallboard, gypsum
lath or gypsum plaster shall not be installed until weather
protection for the installation is provided.

International Building Code 2508.2.1

Weather protection. Gypsumwallboard, gypsum
lath or gypsum plaster shall not be installed until weather
protection for the installation is provided.

International Building Code 2508.3

Single-ply application. Edges and ends of gypsum
board shall occur on the framing members, except those edges
and ends that are perpendicular to the framing members. Edges
and ends of gypsum board shall be in moderate contact except
in concealed spaces where fire-resistance-rated construction,
shear resistance or diaphragm action is not required.

Floating angles. Fasteners at the top and bottom
plates of vertical assemblies, or the edges and ends of horizontal
assemblies perpendicular to supports, and at the wall
line are permitted to be omitted except on shear resisting
elements or fire-resistance-rated assemblies. Fasteners shall
be applied in such a manner as not to fracture the face paper
with the fastener head.

International Building Code 2508.3.1

Floating angles. Fasteners at the top and bottom
plates of vertical assemblies, or the edges and ends of horizontal
assemblies perpendicular to supports, and at the wall
line are permitted to be omitted except on shear resisting
elements or fire-resistance-rated assemblies. Fasteners shall
be applied in such a manner as not to fracture the face paper
with the fastener head.

International Building Code 2508.4

Joint treatment. Gypsum board fire-resistance-rated
assemblies shall have joints and fasteners treated.
Exception: Joint and fastener treatment need not be provided
where any of the following conditions occur:
1. Where the gypsum board is to receive a decorative
finish such as wood paneling, battens, acoustical finishes
or any similar application that would be equivalent
to joint treatment.
2. On single-layer systems where joints occur over
wood framing members.
3. Square edge or tongue-and-groove edge gypsum
board (V-edge), gypsum backing board or gypsum
sheathing.
4. On multilayer systems where the joints of adjacent
layers are offset from one to another.
5. Assemblies tested without joint treatment.

International Building Code 2508.5

Horizontal gypsum board diaphragm ceilings. Gypsum
board shall be permitted to be used onwood joists to create
a horizontal diaphragm ceiling in accordance with Table
2508.5.

Diaphragm proportions. The maximum allowable
diaphragm proportions shall be 11/2:1 between shear
resisting elements. Rotation or cantilever conditions shall
not be permitted.

Installation. Gypsum board used in a horizontal
diaphragm ceiling shall be installed perpendicular to ceiling
framing members. End joints of adjacent courses of gypsum
board shall not occur on the same joist.

Blocking of perimeter edges. All perimeter edges
shall be blocked using a wood member not less than 2-inch
by 6-inch (51 mm by 159 mm) nominal dimension. Blocking
material shall be installed flat over the top plate of the
wall to provide a nailing surface not less than 2 inches (51
mm) in width for the attachment of the gypsum board.

Fasteners. Fasteners used for the attachment of
gypsum board to a horizontal diaphragm ceiling shall be as
defined in Table 2508.5. Fasteners shall be spaced not more
than 7 inches (178 mm) on center (o.c.) at all supports,
including perimeter blocking, and not more than 3/8 inch
(9.5 mm) from the edges and ends of the gypsum board.

Lateral force restrictions. Gypsum board shall
not be used in diaphragm ceilings to resist lateral forces
imposed by masonry or concrete construction.

International Building Code 2508.5.1

Diaphragm proportions. The maximum allowable
diaphragm proportions shall be 11/2:1 between shear
resisting elements. Rotation or cantilever conditions shall
not be permitted.

International Building Code 2508.5.2

Installation. Gypsum board used in a horizontal
diaphragm ceiling shall be installed perpendicular to ceiling
framing members. End joints of adjacent courses of gypsum
board shall not occur on the same joist.

International Building Code 2508.5.3

Blocking of perimeter edges. All perimeter edges
shall be blocked using a wood member not less than 2-inch
by 6-inch (51 mm by 159 mm) nominal dimension. Blocking
material shall be installed flat over the top plate of the
wall to provide a nailing surface not less than 2 inches (51
mm) in width for the attachment of the gypsum board.

International Building Code 2508.5.4

Fasteners. Fasteners used for the attachment of
gypsum board to a horizontal diaphragm ceiling shall be as
defined in Table 2508.5. Fasteners shall be spaced not more
than 7 inches (178 mm) on center (o.c.) at all supports,
including perimeter blocking, and not more than 3/8 inch
(9.5 mm) from the edges and ends of the gypsum board.

International Building Code 2508.5.5

Lateral force restrictions. Gypsum board shall
not be used in diaphragm ceilings to resist lateral forces
imposed by masonry or concrete construction.