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Chapter 7 — FIRE AND SMOKE PROTECTION FEATURES

Section 721 — PRESCRIPTIVE FIRE RESISTANCE

2025 California Building Code (Title 24, Part 2) · 2025 edition · updated 2026-07-29 · California

Italicized text is a California amendment to the model code, as printed in the official publication.

721.1 General.

The provisions of this section contain prescriptive details of fire-resistance-rated building elements, components or assemblies. The materials of construction specified in Tables 721.1(1), 721.1(2) and 721.1(3) shall be assumed to have the fire-resistance ratings prescribed therein. Where materials that change the capacity for heat dissipation are incorporated into a fireresistance-rated assembly, fire test results or other substantiating data shall be made available to the building official to show that the required fire-resistance-rating time period is not reduced.

ables 721.1(1), 721.1(2) and 721.1(3) shall be assumed to have the fire-resistance ratings prescribed therein. Where materials that change the capacity for heat dissipation are incorporated into a fireresistance-rated assembly, fire test results or other substantiating data shall be made available to the building official to show that the required fire-resistance-rating time period is not reduced.

TABLE 721.1(1)—MINIMUM PROTECTION OF STRUCTURAL PARTS
BASED ON TIME PERIODS FOR VARIOUS NONCOMBUSTIBLE INSULATING MATERIALSm

** STRUCTURAL**
PARTS TO BE
PROTECTED		 ** ITEM**
NUMBER		 ** INSULATING MATERIAL USED** ** MINIMUM THICKNESS OF INSULATING MATERIAL**
FOR THE FOLLOWING FIRE-RESISTANCE PERIODS
(inches)		 ** MINIMUM THICKNESS OF INSULATING MATERIAL**
FOR THE FOLLOWING FIRE-RESISTANCE PERIODS
(inches)		 ** MINIMUM THICKNESS OF INSULATING MATERIAL**
FOR THE FOLLOWING FIRE-RESISTANCE PERIODS
(inches)		 ** MINIMUM THICKNESS OF INSULATING MATERIAL**
FOR THE FOLLOWING FIRE-RESISTANCE PERIODS
(inches)
** STRUCTURAL**
PARTS TO BE
PROTECTED		 ** ITEM**
NUMBER		 ** INSULATING MATERIAL USED** ** 4 hours** ** 3 hours** ** 2 hours** ** 1 hour**
1. Steel columns
and all of
primary
trusses		 1-1.1 Carbonate, lightweight and sand-lightweight aggregate
concrete, members 6" × 6" or greater (not including sand-
stone, granite and siliceous gravel).a		 21/2 2 11/2 1
1. Steel columns
and all of
primary
trusses		 1-1.2 Carbonate, lightweight and sand-lightweight aggregate
concrete, members 8" × 8" or greater (not including sand-
stone, granite and siliceous gravel).a		 2 11/2 1 1
1. Steel columns
and all of
primary
trusses		 1-1.3 Carbonate, lightweight and sand-lightweight aggregate
concrete, members 12" × 12" or greater (not including sand-
stone, granite and siliceous gravel).a		 11/2 1 1 1
1. Steel columns
and all of
primary
trusses		 1-1.4 Siliceous aggregate concrete and concrete excluded in Item
1-1.1, members 6" × 6" or greater.a		 3 2 11/2 1
1. Steel columns
and all of
primary
trusses		 1-1.5 Siliceous aggregate concrete and concrete excluded in Item
1-1.1, members 8" × 8" or greater.a		 21/2 2 1 1
1. Steel columns
and all of
primary
trusses		 1-1.6 Siliceous aggregate concrete and concrete excluded in Item
1-1.1, members 12" × 12" or greater.a		 2 1 1 1
1. Steel columns
and all of
primary
trusses		 1-2.1 Clay or shale brick with brick and mortar fill.a 33/4 — — 21/4
1. Steel columns
and all of
primary
trusses		 1-3.1 4" hollow clay tile in two 2" layers;1/2" mortar between tile
and column;3/ 8" metal mesh 0.046" wire diameter in hori-
zontal joints; tile fill.a		 4 — — —
1. Steel columns
and all of
primary
trusses		 1-3.2 2" hollow clay tile;3/4" mortar between tile and column;3/8"
metal mesh 0.046" wire diameter in horizontal joints; lime-
stone concrete filla; plastered with3/4" gypsum plaster.		 3 — — —
1. Steel columns
and all of
primary
trusses		 1-3.3 2" hollow clay tile with outside wire ties 0.08" diameter at
each course of tile or3/8" metal mesh 0.046" diameter wire in
horizontal joints; limestone or trap-rock concrete filla extend-
ing 1" outside column on all sides.		 — — 3 —
1. Steel columns
and all of
primary
trusses		 1-3.4 2" hollow clay tile with outside wire ties 0.08" diameter at
each course of tile with or without concrete fill;3/4" mortar
between tile and column.		 — — — 2
1. Steel columns
and all of
primary
trusses		 1-4.1 Cement plaster over metal lath wire tied to3/4" cold-rolled
vertical channels with 0.049" (No. 18 B.W. gage) wire ties
spaced 3" to 6" on center. Plaster mixed 1: 21/2 by volume,
cement to sand.		 — — 21/2
b		 7/8
1. Steel columns
and all of
primary
trusses		 1-5.1 Vermiculite concrete, 1:4 mix by volume over paper-backed
wire fabric lath wrapped directly around column with addi-
tional 2" × 2" 0.065"/0.065" (No. 16/16 B.W. gage) wire fabric
placed3/4" from outer concrete surface. Wire fabric tied with
0.049" (No. 18B.W. gage) wire spaced 6" on center for inner
layer and 2" on center for outer layer.		 2 — — —

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

FIRE AND SMOKE PROTECTION FEATURES

TABLE 721.1(1)—MINIMUM PROTECTION OF STRUCTURAL PARTS
BASED ON TIME PERIODS FOR VARIOUS NONCOMBUSTIBLE INSULATING MATERIALSm—continued

** STRUCTURAL**
PARTS TO BE
PROTECTED		 ** ITEM**
NUMBER		 ** INSULATING MATERIAL USED** ** MINIMUM THICKNESS OF INSULATING MATERIAL**
FOR THE FOLLOWING FIRE-RESISTANCE PERIODS
(inches)		 ** MINIMUM THICKNESS OF INSULATING MATERIAL**
FOR THE FOLLOWING FIRE-RESISTANCE PERIODS
(inches)		 ** MINIMUM THICKNESS OF INSULATING MATERIAL**
FOR THE FOLLOWING FIRE-RESISTANCE PERIODS
(inches)		 ** MINIMUM THICKNESS OF INSULATING MATERIAL**
FOR THE FOLLOWING FIRE-RESISTANCE PERIODS
(inches)
** STRUCTURAL**
PARTS TO BE
PROTECTED		 ** ITEM**
NUMBER		 ** INSULATING MATERIAL USED** ** 4 hours** ** 3 hours** ** 2 hours** ** 1 hour**
1. Steel columns
and all of
primary
trusses—
continued		 1-6.1 Perlite or vermiculite gypsum plaster over metal lath
wrapped around column and furred 11/4" from column
flanges. Sheets lapped at ends and tied at 6" intervals with
0.049" (No. 18 B.W. gage) tie wire. Plaster pushed through to
flanges.		 11/2 1 — —
1. Steel columns
and all of
primary
trusses—
continued		 1-6.2 Perlite or vermiculite gypsum plaster over self-furring metal
lath wrapped directly around column, lapped 1" and tied at 6"
intervals with 0.049" (No. 18 B.W. gage) wire.		 13/4 13/8 1 —
1. Steel columns
and all of
primary
trusses—
continued		 1-6.3 Perlite or vermiculite gypsum plaster on metal lath applied to
3/4" cold-rolled channels spaced 24" apart vertically and
wrapped flatwise around column.		 11/2 — — —
1. Steel columns
and all of
primary
trusses—
continued		 1-6.4 Perlite or vermiculite gypsum plaster over two layers of1/2"
plain full-length gypsum lath applied tight to column flanges.
Lath wrapped with 1" hexagonal mesh of No. 20-gage wire
and tied with doubled 0.035" diameter (No. 18 B.W. gage)
wire ties spaced 23" on center. For three-coat work, the plas-
ter mix for the second coat shall not exceed 100 pounds of
gypsum to 21/2 cubic feet of aggregate for the 3-hour system.		 21/2 2 — —
1. Steel columns
and all of
primary
trusses—
continued		 1-6.5 Perlite or vermiculite gypsum plaster over one layer of1/2" plain
full-length gypsum lath applied tight to column flanges. Lath
tied with doubled 0.049" (No. 18 B.W. gage) wire ties spaced 23"
on center and scratch coat wrapped with 1" hexagonal mesh
0.035" (No. 20 B.W. gage) wire fabric. For three-coat work, the
plaster mix for the second coat shall not exceed 100 pounds of
gypsum to 21/2 cubic feet of aggregate.		 — 2 — —
1. Steel columns
and all of
primary
trusses—
continued		 1-7.1 Multiple layers of1/2" gypsum wallboardc adhesivelyd secured
to column flanges and successive layers. Wallboard applied
without horizontal joints. Corner edges of each layer stag-
gered. Wallboard layer below outer layer secured to column
with doubled 0.049" (No. 18 B.W. gage) steel wire ties spaced
15" on center. Exposed corners taped and treated.		 — — 2 1
1. Steel columns
and all of
primary
trusses—
continued		 1-7.2 Three layers of5/ 8" Type X gypsum wallboard.c First and
second layer held in place by1/8" diameter by 13/8" long ring
shank nails with5/16" diameter heads spaced 24" on center at
corners. Middle layer also secured with metal straps at mid-
height and 18" from each end, and by metal corner bead at
each corner held by the metal straps. Third layer attached to
corner bead with 1" long gypsum wallboard screws spaced
12" on center.		 — — 17/8 —
1. Steel columns
and all of
primary
trusses—
continued		 1-7.3 Three layers of5/ 8" Type X gypsum wallboard,c each layer
screw attached to 15/ 8" steel studs 0.018" thick (No. 25
carbon sheet steel gage) at each corner of column. Middle
layer also secured with 0.049" (No. 18 B.W. gage) double-
strand steel wire ties, 24" on center. Screws are No. 6 by 1"
spaced 24" on center for inner layer, No. 6 by 15/8" spaced 12"
on center for middle layer and No. 8 by 21/4" spaced 12" on
center for outer layer.		 — 17/8 — —

7-44 2025 CALIFORNIA BUILDING CODE

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

FIRE AND SMOKE PROTECTION FEATURES

TABLE 721.1(1)—MINIMUM PROTECTION OF STRUCTURAL PARTS
BASED ON TIME PERIODS FOR VARIOUS NONCOMBUSTIBLE INSULATING MATERIALSm—continued

** STRUCTURAL**
PARTS TO BE
PROTECTED		 ** ITEM**
NUMBER		 ** INSULATING MATERIAL USED** ** MINIMUM THICKNESS OF INSULATING MATERIAL**
FOR THE FOLLOWING FIRE-RESISTANCE PERIODS
(inches)		 ** MINIMUM THICKNESS OF INSULATING MATERIAL**
FOR THE FOLLOWING FIRE-RESISTANCE PERIODS
(inches)		 ** MINIMUM THICKNESS OF INSULATING MATERIAL**
FOR THE FOLLOWING FIRE-RESISTANCE PERIODS
(inches)		 ** MINIMUM THICKNESS OF INSULATING MATERIAL**
FOR THE FOLLOWING FIRE-RESISTANCE PERIODS
(inches)
** STRUCTURAL**
PARTS TO BE
PROTECTED		 ** ITEM**
NUMBER		 ** INSULATING MATERIAL USED** ** 4 hours** ** 3 hours** ** 2 hours** ** 1 hour**
1. Steel columns
and all of
primary
trusses—
continued		 1-8.1 Wood-fibered gypsum plaster mixed 1:1 by weight gypsum-
to-sand aggregate applied over metal lath. Lath lapped 1"
and tied 6" on center at all end, edges and spacers with
0.049" (No. 18 B.W. gage) steel tie wires. Lath applied over1/2"
spacers made of3/ 4" furring channel with 2" legs bent around
each corner. Spacers located 1" from top and bottom of
member and not greater than 40" on center and wire tied
with a single strand of 0.049" (No. 18 B.W. gage) steel tie
wires. Corner bead tied to the lath at 6" on center along each
corner to provide plaster thickness.		 — — 15/8 —
1. Steel columns
and all of
primary
trusses—
continued		 1-9.1 Minimum W8x35 wide flange steel column (w/d ≥ 0.75) with
each web cavity filled even with the flange tip with normal
weight carbonate or siliceous aggregate concrete (3,000 psi
minimum compressive strength with 145 pcf ± 3 pcf unit
weight). Reinforce the concrete in each web cavity with a
minimum No. 4 deformed reinforcing bar installed vertically
and centered in the cavity, and secured to the column web
with a minimum No. 2 horizontal deformed reinforcing bar
welded to the web every 18" on center vertically. As an alter-
native to the No. 4 rebar,3/4" diameter by 3" long headed
studs, spaced at 12" on center vertically, shall be welded on
each side of the web mid-way between the column flanges.		 — — — See
Note n
2. Webs or
flanges of steel
beams and
girders		 2-1.1 Carbonate, lightweight and sand-lightweight aggregate
concrete (not including sandstone, granite and siliceous
gravel) with 3" or finer metal mesh placed 1" from the
finished surface anchored to the top flange and providing not
less than 0.025 square inch of steel area per foot in each
direction.		 2 11/2 1 1
2. Webs or
flanges of steel
beams and
girders		 2-1.2 Siliceous aggregate concrete and concrete excluded in Item
2-1.1 with 3" or finer metal mesh placed 1" from the finished
surface anchored to the top flange and providing not less
than 0.025 square inch of steel area per foot in each direction.		 21/2 2 11/2 1
2. Webs or
flanges of steel
beams and
girders		 2-2.1 Cement plaster on metal lath attached to3/4" cold-rolled
channels with 0.04" (No. 18 B.W. gage) wire ties spaced 3" to
6" on center. Plaster mixed 1: 21/2 by volume, cement to sand.		 — — 21/2
b		 7/8
2. Webs or
flanges of steel
beams and
girders		 2-3.1 Vermiculite gypsum plaster on a metal lath cage, wire tied to
0.165" diameter (No. 8 B.W. gage) steel wire hangers wrapped
around beam and spaced 16" on center. Metal lath ties
spaced approximately 5" on center at cage sides and bottom.		 — 7/8 — —

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

FIRE AND SMOKE PROTECTION FEATURES

TABLE 721.1(1)—MINIMUM PROTECTION OF STRUCTURAL PARTS
BASED ON TIME PERIODS FOR VARIOUS NONCOMBUSTIBLE INSULATING MATERIALSm—continued

** STRUCTURAL**
PARTS TO BE
PROTECTED		 ** ITEM**
NUMBER		 ** INSULATING MATERIAL USED** ** MINIMUM THICKNESS OF INSULATING MATERIAL**
FOR THE FOLLOWING FIRE-RESISTANCE PERIODS
(inches)		 ** MINIMUM THICKNESS OF INSULATING MATERIAL**
FOR THE FOLLOWING FIRE-RESISTANCE PERIODS
(inches)		 ** MINIMUM THICKNESS OF INSULATING MATERIAL**
FOR THE FOLLOWING FIRE-RESISTANCE PERIODS
(inches)		 ** MINIMUM THICKNESS OF INSULATING MATERIAL**
FOR THE FOLLOWING FIRE-RESISTANCE PERIODS
(inches)
** STRUCTURAL**
PARTS TO BE
PROTECTED		 ** ITEM**
NUMBER		 ** INSULATING MATERIAL USED** ** 4 hours** ** 3 hours** ** 2 hours** ** 1 hour**
2. Webs or
flanges of steel
beams and
girders—
continued		 2-4.1 Two layers of5/8" Type X gypsum wallboardc are attached to
U-shaped brackets spaced 24" on center. 0.018" thick (No. 25
carbon sheet steel gage) 15/8" deep by 1" galvanized steel
runner channels are first installed parallel to and on each side
of the top beam flange to provide a1/2" clearance to the
flange. The channel runners are attached to steel deck or
concrete floor construction with approved fasteners spaced
12" on center. U-shaped brackets are formed from members
identical to the channel runners. At the bent portion of the U-
shaped bracket, the flanges of the channel are cut out so that
15/8"-deep corner channels can be inserted without attach-
ment parallel to each side of the lower flange. As an
alternative, 0.021" thick (No. 24 carbon sheet steel gage) 1" ×
2" runner and corner angles shall be used in lieu of channels,
and the web cutouts in the U-shaped brackets shall not be
required. Each angle is attached to the bracket with1/2"-long
No. 8 self-drilling screws. The vertical legs of the U-shaped
bracket are attached to the runners with one1/2"-long No. 8
self-drilling screw. The completed steel framing provides a 2
1/8" and 11/2" space between the inner layer of wallboard and
the sides and bottom of the steel beam, respectively. The
inner layer of wallboard is attached to the top runners and
bottom corner channels or corner angles with 11/4"-long No. 6
self-drilling screws spaced 16" on center. The outer layer of
wallboard is applied with 13/4"-long No. 6 self-drilling screws
spaced 8" on center. The bottom corners are reinforced with
metal corner beads.		 — — 11/4 —
2. Webs or
flanges of steel
beams and
girders—
continued		 2-4.2 Three layers of5/8" Type X gypsum wallboardc attached to a
steel suspension system as described immediately above utiliz-
ing the 0.018" thick (No. 25 carbon sheet steel gage) 1" × 2"
lower corner angles. The framing is located so that a 21/8" and 2"
space is provided between the inner layer of wallboard and the
sides and bottom of the beam, respectively. The first two layers
of wallboard are attached as described immediately above. A
layer of 0.035" thick (No. 20 B.W. gage) 1" hexagonal galvanized
wire mesh is applied under the soffit of the middle layer and up
the sides approximately 2". The mesh is held in position with
the No. 6 15/8"-long screws installed in the vertical leg of the
bottom corner angles. The outer layer of wallboard is attached
with No. 6 21/4"-long screws spaced 8" on center. One screw is
installed at the mid-depth of the bracket in each layer. Bottom
corners are finished as described above.		 — 17/8 — —
3. Bonded
pretensioned
reinforcement
in prestressed
concretee		 3-1.1 Carbonate, lightweight, sand-lightweight and siliceousf
aggregate concrete
3. Bonded
pretensioned
reinforcement
in prestressed
concretee		 3-1.1 Beams or girders 4g 3g 21/2 11/2
3. Bonded
pretensioned
reinforcement
in prestressed
concretee		 3-1.1 Solidh 2 11/2 1
4. Bonded or
unbonded post-
tensioned
tendons in
prestressed
concretee, i		 4-1.1 Carbonate, lightweight, sand-lightweight and siliceousf
aggregate concrete
Unrestrained members:
4. Bonded or
unbonded post-
tensioned
tendons in
prestressed
concretee, i		 4-1.1 Solid slabsh — 2 11/2 —
4. Bonded or
unbonded post-
tensioned
tendons in
prestressed
concretee, i		 4-1.1 Beams and girdersj Beams and girdersj Beams and girdersj Beams and girdersj Beams and girdersj
4. Bonded or
unbonded post-
tensioned
tendons in
prestressed
concretee, i		 4-1.1 8" wide 41/2 21/2 13/4
4. Bonded or
unbonded post-
tensioned
tendons in
prestressed
concretee, i		 4-1.1 greater than 12" wide 3 21/2 2 11/2
4. Bonded or
unbonded post-
tensioned
tendons in
prestressed
concretee, i		 4-1.2 Carbonate, lightweight, sand-lightweight and siliceous
aggregate
Restrained members:k
4. Bonded or
unbonded post-
tensioned
tendons in
prestressed
concretee, i		 4-1.2 Solid slabsh 11/4 1 3/4 —
4. Bonded or
unbonded post-
tensioned
tendons in
prestressed
concretee, i		 4-1.2 Beams and girdersj Beams and girdersj Beams and girdersj Beams and girdersj Beams and girdersj
4. Bonded or
unbonded post-
tensioned
tendons in
prestressed
concretee, i		 4-1.2 8" wide 21/2 2 13/4 —
4. Bonded or
unbonded post-
tensioned
tendons in
prestressed
concretee, i		 4-1.2 greater than 12" wide 2 13/4 11/2 —

7-46 2025 CALIFORNIA BUILDING CODE

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

FIRE AND SMOKE PROTECTION FEATURES

TABLE 721.1(1)—MINIMUM PROTECTION OF STRUCTURAL PARTS
BASED ON TIME PERIODS FOR VARIOUS NONCOMBUSTIBLE INSULATING MATERIALSm—continued

** STRUCTURAL**
PARTS TO BE
PROTECTED		 ** ITEM**
NUMBER		 ** INSULATING MATERIAL USED** ** MINIMUM THICKNESS OF INSULATING MATERIAL**
FOR THE FOLLOWING FIRE-RESISTANCE PERIODS
(inches)		 ** MINIMUM THICKNESS OF INSULATING MATERIAL**
FOR THE FOLLOWING FIRE-RESISTANCE PERIODS
(inches)		 ** MINIMUM THICKNESS OF INSULATING MATERIAL**
FOR THE FOLLOWING FIRE-RESISTANCE PERIODS
(inches)		 ** MINIMUM THICKNESS OF INSULATING MATERIAL**
FOR THE FOLLOWING FIRE-RESISTANCE PERIODS
(inches)
** STRUCTURAL**
PARTS TO BE
PROTECTED		 ** ITEM**
NUMBER		 ** INSULATING MATERIAL USED** ** 4 hours** ** 3 hours** ** 2 hours** ** 1 hour**
5. Reinforcing
steel in rein-
forced concrete
columns, beams
girders and
trusses		 5-1.1 Carbonate, lightweight and sand-lightweight aggregate
concrete, members 12" or larger, square or round. (Size limit
does not apply to beams and girders monolithic with floors.)		 11/2 11/2 11/2 11/2
5. Reinforcing
steel in rein-
forced concrete
columns, beams
girders and
trusses		 5-1.1 Siliceous aggregate concrete, members 12" or larger, square
or round. (Size limit does not apply to beams and girders
monolithic with floors.)		 2 11/2 11/2 11/2
6. Reinforcing
steel in rein-
forced concrete
joistsl		 6-1.1 Carbonate, lightweight and sand-lightweight aggregate
concrete		 11/4 11/4 1 3/4
6. Reinforcing
steel in rein-
forced concrete
joistsl		 6-1.2 Siliceous aggregate concrete 13/4 11/2 1 3/4
7. Reinforcing
and tie rods in
floor and roof
slabsl		 7-1.1 Carbonate, lightweight and sand-lightweight aggregate
concrete		 1 1 3/4 3/4
7. Reinforcing
and tie rods in
floor and roof
slabsl		 7-1.2 Siliceous aggregate concrete 11/4 1 1 3/4

For SI: 1 inch = 25.4 mm, 1 square inch = 645.2 mm2, 1 cubic foot = 0.0283 m3, 1 pound per cubic foot = 16.02 kg/m3.
a. Reentrant parts of protected members to be filled solidly.
b. Two layers of equal thickness with a3/4-inch airspace between.
c. For all of the construction with gypsum wallboard described in Table 721.1(1), gypsum base for veneer plaster of the same size, thickness and core type shall be permitted to
be substituted for gypsum wallboard, provided that attachment is identical to that specified for the wallboard and the joints on the face layer are reinforced, and the entire
surface is covered with not less than1/16-inch gypsum veneer plaster.
d. An approved adhesive qualified under ASTM E119 or UL 263.
e. Where lightweight or sand-lightweight concrete having an oven-dry weight of 110 pounds per cubic foot or less is used, the tabulated minimum cover shall be permitted to be
reduced 25 percent, except that the reduced cover shall be not less than3/4 inch in slabs or 11/2 inches in beams or girders.
f. For solid slabs of siliceous aggregate concrete, increase tendon cover 20 percent.
g. Adequate provisions against spalling shall be provided by U-shaped or hooped stirrups spaced not to exceed the depth of the member with a clear cover of 1 inch.
h. Prestressed slabs shall have a thickness not less than that required in Table 721.1(3) for the respective fire-resistance time period.
i. Fire coverage and end anchorages shall be as follows: Cover to the prestressing steel at the anchor shall be1/2 inch greater than that required away from the anchor. Minimum
cover to steel-bearing plate shall be 1 inch in beams and3/ 4 inch in slabs.
j. For beam widths between 8 inches and 12 inches, cover thickness shall be permitted to be determined by interpolation.
k. Interior spans of continuous slabs, beams and girders shall be permitted to be considered restrained.
l. For use with concrete slabs having a comparable fire endurance where members are framed into the_structure_ in such a manner as to provide equivalent performance to that
of monolithic concrete construction.
m.Generic fire-resistance ratings (those not designated as PROPRIETARY* in the listing) in GA-600 shall be accepted as if herein specified.
n. Additional insulating material is not required on the exposed outside face of the column flange to achieve a 1-hour fire-resistance rating.

TABLE 721.1(2)—RATED FIRE-RESISTANCE PERIODS FOR VARIOUS WALLS AND PARTITIONSa, o, p

MATERIAL ITEM
NUMBER		 CONSTRUCTION MINIMUM FINISHED THICKNESS FACE-TO-FACEb
(inches)		 MINIMUM FINISHED THICKNESS FACE-TO-FACEb
(inches)		 MINIMUM FINISHED THICKNESS FACE-TO-FACEb
(inches)		 MINIMUM FINISHED THICKNESS FACE-TO-FACEb
(inches)
MATERIAL ITEM
NUMBER		 CONSTRUCTION 4 hours 3 hours 2 hours 1 hour
1. Brick of clay or
shale		 1-1.1 Solid brick of clay or shale.c 6 4.9 3.8 2.7
1. Brick of clay or
shale		 1-1.2 Hollow brick, not filled. 5.0 4.3 3.4 2.3
1. Brick of clay or
shale		 1-1.3 Hollow brick unit wall, grout or filled with perlite
vermiculite or expanded shale aggregate.		 6.6 5.5 4.4 3.0
1. Brick of clay or
shale		 1-2.1 4" nominal thick units not less than 75 percent solid backed
with a hat-shaped metal furring channel3/4" thick formed from
0.021" sheet metal attached to the brick wall on 24" centers
with approved fasteners, and1/2" Type X gypsum wallboard
attached to the metal furring strips with 1"-long Type S screws
spaced 8" on center.		 — — 5d —
2. Combination
of clay brick and
load-bearing
hollow clay tile		 2-1.1 4" solid brick and 4" tile (not less than 40 percent solid). — 8 — —
2. Combination
of clay brick and
load-bearing
hollow clay tile		 2-1.2 4" solid brick and 8" tile (not less than 40 percent solid). 12 — — —
3. Concrete
masonry units		 3-1.1f, g Expanded slag or pumice. 4.7 4.0 3.2 2.1
3. Concrete
masonry units		 3-1.2f, g Expanded clay, shale or slate. 5.1 4.4 3.6 2.6
3. Concrete
masonry units		 3-1.3f Limestone, cinders or air-cooled slag. 5.9 5.0 4.0 2.7
3. Concrete
masonry units		 3-1.4f, g Calcareous or siliceous gravel. 6.2 5.3 4.2 2.8

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

FIRE AND SMOKE PROTECTION FEATURES

TABLE 721.1(2)—RATED FIRE-RESISTANCE PERIODS FOR VARIOUS WALLS AND PARTITIONSa, o, p—continued

MATERIAL ITEM
NUMBER		 CONSTRUCTION MINIMUM FINISHED THICKNESS FACE-TO-FACEb
(inches)		 MINIMUM FINISHED THICKNESS FACE-TO-FACEb
(inches)		 MINIMUM FINISHED THICKNESS FACE-TO-FACEb
(inches)		 MINIMUM FINISHED THICKNESS FACE-TO-FACEb
(inches)
MATERIAL ITEM
NUMBER		 CONSTRUCTION 4 hours 3 hours 2 hours 1 hour
4. Solid
concreteh, i		 4-1.1 Siliceous aggregate concrete. 7.0 6.2 5.0 3.5
4. Solid
concreteh, i		 4-1.1 Carbonate aggregate concrete. 6.6 5.7 4.6 3.2
4. Solid
concreteh, i		 4-1.1 Sand-lightweight concrete. 5.4 4.6 3.8 2.7
4. Solid
concreteh, i		 4-1.1 Lightweight concrete. 5.1 4.4 3.6 2.5
5. Glazed or
unglazed facing
tile, nonload-
bearing		 5-1.1 One 2" unit cored 15 percent maximum and one 4" unit cored
25 percent maximum with3/4" mortar-filled collar joint. Unit
positions reversed in alternate courses.		 — 63/8 — —
5. Glazed or
unglazed facing
tile, nonload-
bearing		 5-1.2 One 2" unit cored 15 percent maximum and one 4" unit cored
40 percent maximum with3/4" mortar-filled collar joint. Unit
positions side with3/4" gypsum plaster. Two wythes tied
together every fourth course with No. 22 gage corrugated
metal ties.		 — 63/4 — —
5. Glazed or
unglazed facing
tile, nonload-
bearing		 5-1.3 One unit with three cells in wall thickness, cored 29 percent
maximum.		 — — 6 —
5. Glazed or
unglazed facing
tile, nonload-
bearing		 5-1.4 One 2" unit cored 22 percent maximum and one 4" unit cored
41 percent maximum with1/4" mortar-filled collar joint. Two
wythes tied together every third course with 0.030"(No. 22
galvanized sheet steel gage) corrugated metal ties.		 — — 6 —
5. Glazed or
unglazed facing
tile, nonload-
bearing		 5-1.5 One 4" unit cored 25 percent maximum with3/4" gypsum plas-
ter on one side.		 — — 43/4 —
5. Glazed or
unglazed facing
tile, nonload-
bearing		 5-1.6 One 4" unit with two cells in wall thickness, cored 22 percent
maximum.		 — — — 4
5. Glazed or
unglazed facing
tile, nonload-
bearing		 5-1.7 One 4" unit cored 30 percent maximum with3/4" vermiculite
gypsum plaster on one side.		 — — 41/2 —
5. Glazed or
unglazed facing
tile, nonload-
bearing		 5-1.8 One 4" unit cored 39 percent maximum with3/4" gypsum plas-
ter on one side.		 — — — 41/2
6. Solid gypsum
plaster		 6-1.1 3/4" by 0.055" (No. 16 carbon sheet steel gage) vertical cold-
rolled channels, 16" on center with 2.6-pound flat metal lath
applied to one face and tied with 0.049" (No. 18 B.W. gage)
wire at 6" spacing. Gypsum plaster each side mixed 1:2 by
weight, gypsum to sand aggregate.		 — — — 2d
6. Solid gypsum
plaster		 6-1.2 3/4" by 0.05" (No. 16 carbon sheet steel gage) cold-rolled chan-
nels 16" on center with metal lath applied to one face and tied
with 0.049" (No. 18 B.W. gage) wire at 6" spacing. Perlite or
vermiculite gypsum plaster each side. For three-coat work, the
plaster mix for the second coat shall not exceed 100 pounds of
gypsum to 21/2 cubic feet of aggregate for the 1-hour system.		 — — 21/2
d		 2d
6. Solid gypsum
plaster		 6-1.3 3/4" by 0.055" (No. 16 carbon sheet steel gage) vertical cold-
rolled channels, 16" on center with3/8" gypsum lath applied to
one face and attached with sheet metal clips. Gypsum plaster
each side mixed 1:2 by weight, gypsum to sand aggregate.		 — — — 2d
6. Solid gypsum
plaster		 6-2.1 Studless with1/2" full-length plain gypsum lath and gypsum
plaster each side. Plaster mixed 1:1 for scratch coat and 1:2 for
brown coat, by weight, gypsum to sand aggregate.		 — — — 2d
6. Solid gypsum
plaster		 6-2.2 Studless with1/2" full-length plain gypsum lath and perlite or
vermiculite gypsum plaste_r_ each side.		 — — 21/2
d		 2d
6. Solid gypsum
plaster		 6-2.3 Studless partition with 3/8" rib metal lath installed vertically
adjacent edges tied 6" on center with No. 18 gage wire ties,
gypsum plaster each side mixed 1:2 by weight, gypsum to sand
aggregate.		 — — — 2d
7. Solid perlite
and Portland
cement		 7-1.1 Perlite mixed in the ratio of 3 cubic feet to 100 pounds of Port-
land cement and machine applied to stud side of 11/2" mesh
by 0.058-inch (No. 17 B.W. gage) paper-backed woven wire
fabric lath wire-tied to 4"-deep steel trussed wirej studs 16" on
center. Wire ties of 0.049" (No. 18 B.W. gage) galvanized steel
wire 6" on center vertically.		 — — 31/8
d		 —

7-48 2025 CALIFORNIA BUILDING CODE

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

FIRE AND SMOKE PROTECTION FEATURES

TABLE 721.1(2)—RATED FIRE-RESISTANCE PERIODS FOR VARIOUS WALLS AND PARTITIONSa, o, p—continued

MATERIAL ITEM
NUMBER		 CONSTRUCTION MINIMUM FINISHED THICKNESS FACE-TO-FACEb
(inches)		 MINIMUM FINISHED THICKNESS FACE-TO-FACEb
(inches)		 MINIMUM FINISHED THICKNESS FACE-TO-FACEb
(inches)		 MINIMUM FINISHED THICKNESS FACE-TO-FACEb
(inches)
MATERIAL ITEM
NUMBER		 CONSTRUCTION 4 hours 3 hours 2 hours 1 hour
8. Solid neat
wood fibered
gypsum plaster		 8-1.1 3/4" by 0.055-inch (No. 16 carbon sheet steel gage) cold-rolled
channels, 12" on center with 2.5-pound flat metal lath applied
to one face and tied with 0.049" (No. 18 B.W. gage) wire at 6"
spacing. Neat gypsum plaster applied each side.		 — — 2d —
9. Solid wall-
board partition		 9-1.1 One full-length layer1/2" Type X gypsum wallboarde laminated
to each side of 1" full-length V-edge gypsum coreboard with
approved laminating compound. Vertical joints of face layer
and coreboard staggered not less than 3".		 — — 2d —
10. Hollow (stud-
less) gypsum
wallboard
partition		 10-1.1 One full-length layer of5/8" Type X gypsum wallboarde
attached to both sides of wood or metal top and bottom
runners laminated to each side of 1" × 6" full-length gypsum
coreboard ribs spaced 2" on center with approved laminating
compound. Ribs centered at vertical joints of face plies and
joints staggered 24" in opposing faces. Ribs shall be permitted
to be recessed 6" from the top and bottom.		 — — — 21/4
d
10. Hollow (stud-
less) gypsum
wallboard
partition		 10-1.2 1" regular gypsum V-edge full-length backing board attached
to both sides of wood or metal top and bottom runners with
nails or 15/8" drywall screws at 24" on center. Minimum width
of runners 15/8". Face layer of1/2" regular full-length gypsum
wallboard laminated to outer faces of backing board with
approved laminating compound.		 — — 45/8
d		 —
11. Noncombus-
tible studs—
interior partition
with plaster each
side		 11-1.1 31/4" × 0.044" (No. 18 carbon sheet steel gage) steel studs
spaced 24" on center.5/8" gypsum plaster on metal lath each
side mixed 1:2 by weight, gypsum to sand aggregate.		 — — — 43/4
d
11. Noncombus-
tible studs—
interior partition
with plaster each
side		 11-1.2 33/8" × 0.055" (No. 16 carbon sheet steel gage) approved nail-
ablek studs spaced 24" on center.5/8" neat gypsum wood-
fibered plaster each side over3/8" rib metal lath nailed to studs
with 6d common nails, 8" on center. Nails driven 11/4" and bent
over.		 — — 55/8 —
11. Noncombus-
tible studs—
interior partition
with plaster each
side		 11-1.3 4" × 0.044" (No. 18 carbon sheet steel gage) channel-shaped
steel studs at 16" on center. On each side approved resilient
clips pressed onto stud flange at 16" vertical spacing,1/4"
pencil rods snapped into or wire tied onto outer loop of clips,
metal lath wire-tied to pencil rods at 6" intervals, 1" perlite
gypsum plaster, each side.		 — 75/8
d		 — —
11. Noncombus-
tible studs—
interior partition
with plaster each
side		 11-1.4 21/2" × 0.044" (No. 18 carbon sheet steel gage) steel studs
spaced 16" on center. Wood fibered gypsum plaster mixed 1:1
by weight gypsum to sand aggregate applied on3/4-pound
metal lath wire tied to studs, each side.3/4" plaster applied
over each face, including finish coat.		 — — 41/4
d		 —
12. Wood studs—
interior partition
with plaster each
side		 12-1.1l, m 2" × 4" wood studs 16" on center with5/8" gypsum plaster on
metal lath. Lath attached by 4d common nails bent over or No.
14 gage by 11/4" by3/4" crown width staples spaced 6" on
center. Plaster mixed 1:11/2 for scratch coat and 1:3 for brown
coat, by weight, gypsum to sand aggregate.		 — — — 51/8
12. Wood studs—
interior partition
with plaster each
side		 12-1.2l 2" × 4" wood studs 16" on center with metal lath and7/8" neat
wood-fibered gypsum plaster each side. Lath attached by 6d
common nails, 7" on center. Nails driven 11/4" and bent over.		 — — 51/2
d		 —
12. Wood studs—
interior partition
with plaster each
side		 12-1.3l 2" × 4" wood studs 16" on center with3/8" perforated or plain
gypsum lath and1/2" gypsum plaster each side. Lath nailed
with 11/8" by No. 13 gage by19/64" head plasterboard blued
nails, 4" on center. Plaster mixed 1:2 by weight, gypsum to
sand aggregate.		 — — — 51/4
12. Wood studs—
interior partition
with plaster each
side		 12-1.4l 2" × 4" wood studs 16" on center with3/8" Type X gypsum lath
and1/2" gypsum plaster each side. Lath nailed with 11/8" by No.
13 gage by19/64" head plasterboard blued nails, 5" on center.
Plaster mixed 1:2 by weight, gypsum to sand aggregate.		 — — — 51/4

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

FIRE AND SMOKE PROTECTION FEATURES

TABLE 721.1(2)—RATED FIRE-RESISTANCE PERIODS FOR VARIOUS WALLS AND PARTITIONSa, o, p—continued

MATERIAL ITEM
NUMBER		 CONSTRUCTION MINIMUM FINISHED THICKNESS FACE-TO-FACEb
(inches)		 MINIMUM FINISHED THICKNESS FACE-TO-FACEb
(inches)		 MINIMUM FINISHED THICKNESS FACE-TO-FACEb
(inches)		 MINIMUM FINISHED THICKNESS FACE-TO-FACEb
(inches)
MATERIAL ITEM
NUMBER		 CONSTRUCTION 4 hours 3 hours 2 hours 1 hour
13. Noncombus-
tible studs—
interior partition
with gypsum
wallboard each
side		 13-1.1 0.018" (No. 25 carbon sheet steel gage) channel-shaped studs
24" on center with one full-length layer of5/8" Type X gypsum
wallboarde applied vertically attached with 1"-long No. 6 dry
wall screws to each stud. Screws are 8" on center around the
perimeter and 12" on center on the intermediate stud. Where
applied horizontally, the Type X gypsum wallboard shall be
attached to 35/8" studs and the horizontal joints shall be stag-
gered with those on the opposite side. Screws for the
horizontal application shall be 8" on center at vertical edges
and 12" on center at intermediate studs.		 — — — 27/8
d
13. Noncombus-
tible studs—
interior partition
with gypsum
wallboard each
side		 13-1.2 0.018" (No. 25 carbon sheet steel gage) channel-shaped studs
25" on center with two full-length layers of1/2" Type X gypsum
wallboarde applied vertically each side. First layer attached
with 1"-long, No. 6 drywall screws, 8" on center around the
perimeter and 12" on center on the intermediate stud. Second
layer applied with vertical joints offset one stud space from
first layer using 15/8" long, No. 6 drywall screws spaced 9" on
center along vertical joints, 12" on center at intermediate
studs and 24" on center along top and bottom runners.		 — — 35/8
d		 —
13. Noncombus-
tible studs—
interior partition
with gypsum
wallboard each
side		 13-1.3 0.055" (No. 16 carbon sheet steel gage) approved nailable
metal studse 24" on center with full-length5/8" Type X gypsum
wallboarde applied vertically and nailed 7" on center with 6d
cement-coated common nails. Approved metal fastener grips
used with nails at vertical butt joints along studs.		 — — — 47/8
14. Wood studs—
interior partition
with gypsum
wallboard each
side		 14-1.1h, m 2" × 4" wood studs 16" on center with two layers of3/8" regular
gypsum wallboarde each side, 4d coolern or wallboardn nails at
8" on center first layer, 5d coolern or wallboardn nails at 8" on
center second layer with laminating compound between
layers, joints staggered. First layer applied full length verti-
cally, second layer applied horizontally or vertically.		 — — — 5
14. Wood studs—
interior partition
with gypsum
wallboard each
side		 14-1.2l, m 2" × 4" wood studs 16" on center with two layers1/2" regular
gypsum wallboarde applied vertically or horizontally each
sidek, joints staggered. Nail base layer with 5d coolern or wall-
boardn nails at 8" on center face layer with 8d coolern or
wallboardn nails at 8" on center.		 — — — 51/2
14. Wood studs—
interior partition
with gypsum
wallboard each
side		 14-1.3l, m 2" × 4" wood studs 24" on center with5/8" Type X gypsum wall-
boarde applied vertically or horizontally nailed with 6d coolern
or wallboardn nails at 7" on center with end joints on nailing
members. Stagger joints each side.		 — — — 43/4
14. Wood studs—
interior partition
with gypsum
wallboard each
side		 14-1.4l 2" × 4" fire-retardant-treated wood studs spaced 24" on center
with one layer of5/8" Type X gypsum wallboarde applied with
face paper grain (long dimension) parallel to studs. Wallboard
attached with 6d coolern or wallboardn nails at 7" on center.		 — — — 43/4
d
14. Wood studs—
interior partition
with gypsum
wallboard each
side		 14-1.5l, m 2" × 4" wood studs 16" on center with two layers5/8" Type X
gypsum wallboarde each side. Base layers applied vertically
and nailed with 6d coolern or wallboardn nails at 9" on center.
Face layer applied vertically or horizontally and nailed with 8d
coolern or wallboardn nails at 7" on center. For nail-adhesive
application, base layers are nailed 6" on center. Face layers
applied with coating of approved wallboard adhesive and
nailed 12" on center.		 — — 6 —
14. Wood studs—
interior partition
with gypsum
wallboard each
side		 14-1.6l 2" × 3" fire-retardant-treated wood studs spaced 24" on center
with one layer of5/8" Type X gypsum wallboarde applied with
face paper grain (long dimension) at right angles to studs.
Wallboard attached with 6d cement-coated box nails spaced
7" on center.		 — — — 35/8
d

7-50 2025 CALIFORNIA BUILDING CODE

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

FIRE AND SMOKE PROTECTION FEATURES

TABLE 721.1(2)—RATED FIRE-RESISTANCE PERIODS FOR VARIOUS WALLS AND PARTITIONSa, o, p—continued

MATERIAL ITEM
NUMBER		 CONSTRUCTION MINIMUM FINISHED THICKNESS FACE-TO-FACEb
(inches)		 MINIMUM FINISHED THICKNESS FACE-TO-FACEb
(inches)		 MINIMUM FINISHED THICKNESS FACE-TO-FACEb
(inches)		 MINIMUM FINISHED THICKNESS FACE-TO-FACEb
(inches)
MATERIAL ITEM
NUMBER		 CONSTRUCTION 4 hours 3 hours 2 hours 1 hour
15. Exterior or
interior walls		 15-1.1l, m Exterior surface with3/4" drop siding over1/2" gypsum sheath-
ing on 2" × 4" wood studs at 16" on center, interior surface
treatment as required for 1-hour-rated exterior or interior 2" ×
4" wood stud partitions. Gypsum sheathing nailed with 13/4"
by No.11 gage by7/16" head galvanized nails at 8" on center.
Siding nailed with 7d galvanized smooth box nails.		 — — — Varies
15. Exterior or
interior walls		 15-1.2l, m 2" × 4" wood studs 16" on center with metal lath and3/4"
cement plaster on each side. Lath attached with 6d common
nails 7" on center driven to 1" minimum penetration and bent
over. Plaster mix 1:4 for scratch coat and 1:5 for brown coat, by
volume, cement to sand.		 — — — 53/8
15. Exterior or
interior walls		 15-1.3l, m 2" × 4" wood studs 16" on center with7/8" cement plaster
(measured from the face of studs) on the exterior surface with
interior surface treatment as required for interior wood stud
partitions in this table. Plaster mix 1:4 for scratch coat and 1:5
for brown coat, by volume, cement to sand.		 — — — Varies
15. Exterior or
interior walls		 15-1.4 35/8" No. 16 gage noncombustible studs 16" on center with7/8"
cement plaster (measured from the face of the studs) on the
exterior surface with interior surface treatment as required for
interior, nonbearing, noncombustible stud partitions in this
table. Plaster mix 1:4 for scratch coat and 1:5 for brown coat,
by volume, cement to sand.		 — — — Variesd
15. Exterior or
interior walls		 15-1.5m 21/4" × 33/4" clay face brick with cored holes over1/ 2" gypsum
sheathing on exterior surface of 2" × 4" wood studs at 16" on
center and two layers5/8" Type X gypsum wallboarde on inte-
rior surface. Sheathing placed horizontally or vertically with
vertical joints over studs nailed 6" on center with 13/4" × No. 11
gage by7/16" head galvanized nails. Inner layer of wallboard
placed horizontally or vertically and nailed 8" on center with
6d coolern or wallboardn nails. Outer layer of wallboard placed
horizontally or vertically and nailed 8" on center with 8d cool-
ern or wallboardn nails. Joints staggered with vertical joints
over studs. Outer layer joints taped and finished with
compound. Nail heads covered with joint compound. 0.035
inch (No. 20 galvanized sheet gage) corrugated galvanized
steel wall ties3/4" by 65/8" attached to each stud with two 8d
coolern or wallboardn nails every sixth course of bricks.		 — — 10 —
15. Exterior or
interior walls		 15-1.6l, m 2" × 6" fire-retardant-treated wood studs 16" on center. Inte-
rior face has two layers of5/8" Type X gypsum with the base
layer placed vertically and attached with 6d box nails 12"on
center. The face layer is placed horizontally and attached with
8d box nails 8" on center at joints and 12" on center elsewhere.
The exterior face has a base layer of5/8" Type X gypsum
sheathing placed vertically with 6d box nails 8" on center at
joints and 12" on center elsewhere. An approved building
paper is next applied, followed by self-furred exterior lath
attached with 21/2", No. 12 gage galvanized roofing nails with a
3/8" diameter head and spaced 6" on center along each stud.
Cement plaster consisting of a1/2" brown coat is then applied.
The scratch coat is mixed in the proportion of 1:3 by weight,
cement to sand with 10 pounds of hydrated lime and 3 pounds
of approved additives or admixtures per sack of cement. The
brown coat is mixed in the proportion of 1:4 by weight, cement
to sand with the same amounts of hydrated lime and
approved additives or admixtures used in the scratch coat.		 — — 81/4 —

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

FIRE AND SMOKE PROTECTION FEATURES

TABLE 721.1(2)—RATED FIRE-RESISTANCE PERIODS FOR VARIOUS WALLS AND PARTITIONSa, o, p—continued

MATERIAL ITEM
NUMBER		 CONSTRUCTION MINIMUM FINISHED THICKNESS FACE-TO-FACEb
(inches)		 MINIMUM FINISHED THICKNESS FACE-TO-FACEb
(inches)		 MINIMUM FINISHED THICKNESS FACE-TO-FACEb
(inches)		 MINIMUM FINISHED THICKNESS FACE-TO-FACEb
(inches)
MATERIAL ITEM
NUMBER		 CONSTRUCTION 4 hours 3 hours 2 hours 1 hour
15. Exterior or
interior walls—
continued		 15-1.7l, m 2" × 6" wood studs 16" on center. The exterior face has a layer
of5/8" Type X gypsum sheathing placed vertically with 6d box
nails 8" on center at joints and 12" on center elsewhere. An
approved building paper is next applied, followed by 1" by No.
18 gage self-furred exterior lath attached with 8d by 21/2"-long
galvanized roofing nails spaced 6" on center along each stud.
Cement plaster consisting of a1/2" scratch coat, a bonding
agent and a1/2" brown coat and a finish coat is then applied.
The scratch coat is mixed in the proportion of 1:3 by weight,
cement to sand with 10 pounds of hydrated lime and 3 pounds
of approved additives or admixtures per sack of cement. The
brown coat is mixed in the proportion of 1:4 by weight, cement
to sand with the same amounts of hydrated lime and
approved additives or admixtures used in the scratch coat.
The interior is covered with3/8" gypsum lath with 1" hexagonal
mesh of 0.035 inch (No. 20 B.W. gage) woven wire lath furred
out5/16" and 1" perlite or vermiculite gypsum plaster. Lath
nailed with 11/8" by No. 13 gage by19/64" head plasterboard
glued nails spaced 5" on center. Mesh attached by 13/4" by No.
12 gage by3/8" head nails with3/8" furrings, spaced 8" on
center. The plaster mix shall not exceed 100 pounds of gypsum
to 21/2 cubic feet of aggregate.		 — — 83/8 —
15. Exterior or
interior walls—
continued		 15-1.8l, m 2" × 6" wood studs 16" on center. The exterior face has a layer
of5/8" Type X gypsum sheathing placed vertically with 6d box
nails 8" on center at joints and 12" on center elsewhere. An
approved building paper is next applied, followed by 11/2" by
No. 17 gage self-furred exterior lath attached with 8d by 21/2"-
long galvanized roofing nails spaced 6" on center along each
stud. Cement plaster consisting of a1/2" scratch coat and a1/2"
brown coat is then applied. The plaster shall be permitted to
be placed by machine. The scratch coat is mixed in the propor-
tion of 1:4 by weight, plastic cement to sand. The brown coat is
mixed in the proportion of 1:5 by weight, plastic cement to
sand. The interior is covered with3/8" gypsum lath with 1"
hexagonal mesh of No. 20-gage woven wire lath furred out5/16"
and 1" perlite or vermiculite gypsum plaster. Lath nailed with
11/8" by No. 13 gage by19/64" head plasterboard glued nails
spaced 5" on center. Mesh attached by 13/4" by No.12 gage by
3/ 8" head nails with3/8" furrings, spaced 8" on center. The plas-
ter mix shall not exceed 100 pounds of gypsum to 21/2 cubic
feet of aggregate.		 — — 83/8 —
15. Exterior or
interior walls—
continued		 15-1.9 4" No. 18 gage, nonload-bearing metal studs, 16" on center,
with 1" Portland cement lime plaster (measured from the back
side of the3/4-pound expanded metal lath) on the exterior
surface. Interior surface to be covered with 1" of gypsum plas-
ter on3/4-pound expanded metal lath proportioned by
weight—1:2 for scratch coat, 1:3 for brown, gypsum to sand.
Lath on one side of the partition fastened to1/4" diameter
pencil rods supported by No. 20 gage metal clips, located 16"
on center vertically, on each stud. 3" thick mineral fiber insu-
lating batts friction fitted between the studs.		 — — 61/2
d		 —

7-52 2025 CALIFORNIA BUILDING CODE

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

FIRE AND SMOKE PROTECTION FEATURES

TABLE 721.1(2)—RATED FIRE-RESISTANCE PERIODS FOR VARIOUS WALLS AND PARTITIONSa, o, p—continued

MATERIAL ITEM
NUMBER		 CONSTRUCTION MINIMUM FINISHED THICKNESS FACE-TO-FACEb
(inches)		 MINIMUM FINISHED THICKNESS FACE-TO-FACEb
(inches)		 MINIMUM FINISHED THICKNESS FACE-TO-FACEb
(inches)		 MINIMUM FINISHED THICKNESS FACE-TO-FACEb
(inches)
MATERIAL ITEM
NUMBER		 CONSTRUCTION 4 hours 3 hours 2 hours 1 hour
15. Exterior or
interior walls—
continued		 15-1.10 Steel studs 0.060" thick, 4" deep or 6" at 16" or 24" centers,
with1/2" glass fiber-reinforced concrete (GFRC) on the exterior
surface. GFRC is attached with flex anchors at 24" on center,
with 5" leg welded to studs with two1/2"-long flare-bevel
welds, and 4" foot attached to the GFRC skin with5/8"-thick
GFRC bonding pads that extend 21/2" beyond the flex anchor
foot on both sides. Interior surface to have two layers of1/2"
Type X gypsum wallboard.e The first layer of wallboard to be
attached with 1"-long Type S buglehead screws spaced 24" on
center and the second layer is attached with 15/8"-long Type S
screws spaced at 12" on center. Cavity is to be filled with 5" of
4 pcf (nominal) mineral fiber batts. GFRC has 11/2" returns
packed with mineral fiber and caulked on the exterior.		 — — 61/2 —
15. Exterior or
interior walls—
continued		 15-1.11 Steel studs 0.060" thick, 4" deep or 6" at 16" or 24" centers,
respectively, with1/2" glass fiber-reinforced concrete (GFRC)
on the exterior surface. GFRC is attached with flex anchors at
24" on center, with 5" leg welded to studs with two1/2"-long
flare-bevel welds, and 4" foot attached to the GFRC skin with
5/8"-thick GFRC bonding pads that extend 21/2" beyond the flex
anchor foot on both sides. Interior surface to have one layer of
5/8" Type X gypsum wallboarde, attached with 11/4"-long Type S
buglehead screws spaced 12" on center. Cavity is to be filled
with 5" of 4 pcf (nominal) mineral fiber batts. GFRC has 11/2"
returns packed with mineral fiber and caulked on the exterior.		 — — — 61/8
15. Exterior or
interior walls—
continued		 15-1.12q 2" × 6" wood studs at 16" with double top plates, single
bottom plate; interior and exterior sides covered with5/8" Type
X gypsum wallboard, 4′ wide, applied horizontally or vertically
with vertical joints over studs, and fastened with 21/4" Type S
drywall screws, spaced 12" on center. Cavity to be filled with
51/2" mineral wool insulation.		 — — — 63/4
15. Exterior or
interior walls—
continued		 15-1.13q 2" × 6" wood studs at 16" with double top plates, single
bottom plate; interior and exterior sides covered with5/8" Type
X gypsum wallboard, 4′ wide, applied vertically with all joints
over framing or blocking and fastened with 21/4" Type S
drywall screws, spaced 12" on center. R-19 mineral fiber insu-
lation installed in stud cavity.		 — — — 63/4
15. Exterior or
interior walls—
continued		 15-1.14q 2" × 6" wood studs at 16" with double top plates, single
bottom plate; interior and exterior sides covered with5/8" Type
X gypsum wallboard, 4′ wide, applied horizontally or vertically
with vertical joints over studs, and fastened with 21/4" Type S
drywall screws, spaced 7" on center.		 — — — 63/4
15. Exterior or
interior walls—
continued		 15-1.15q 2" × 4" wood studs at 16" with double top plates, single
bottom plate; interior and exterior sides covered with5/8" Type
X gypsum wallboard and sheathing, respectively, 4′ wide,
applied horizontally or vertically with vertical joints over
studs, and fastened with 21/4" Type S drywall screws, spaced
12" on center. Cavity to be filled with 31/2" mineral wool
insulation.		 — — — 43/4
15. Exterior or
interior walls—
continued		 15-1.16q 2" × 6" wood studs at 24" centers with double top plates,
single bottom plate; interior and exterior side covered with
two layers of5/8" Type X gypsum wallboard, 4′ wide, applied
horizontally with vertical joints over studs. Base layer fastened
with 21/4" Type S drywall screws, spaced 24" on center and
face layer fastened with Type S drywall screws, spaced 8" on
center, wallboard joints covered with paper tape and joint
compound, fastener heads covered with joint compound.
Cavity to be filled with 51/2" mineral wool insulation.		 — — 8 —

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

FIRE AND SMOKE PROTECTION FEATURES

TABLE 721.1(2)—RATED FIRE-RESISTANCE PERIODS FOR VARIOUS WALLS AND PARTITIONSa, o, p—continued

MATERIAL ITEM
NUMBER		 CONSTRUCTION MINIMUM FINISHED THICKNESS FACE-TO-FACEb
(inches)		 MINIMUM FINISHED THICKNESS FACE-TO-FACEb
(inches)		 MINIMUM FINISHED THICKNESS FACE-TO-FACEb
(inches)		 MINIMUM FINISHED THICKNESS FACE-TO-FACEb
(inches)
MATERIAL ITEM
NUMBER		 CONSTRUCTION 4 hours 3 hours 2 hours 1 hour
15. Exterior or
interior walls—
continued		 15-2.1d 35/8" No. 16 gage steel studs at 24" on center or 2" × 4" wood
studs at 24" on center. Metal lath attached to the exterior side
of studs with minimum 1" long No. 6 drywall screws at 6" on
center and covered with minimum3/4" thick Portland cement
plaster. Thin veneer brick units of clay or shale complying with
ASTM C1088, Grade TBS or better, installed in running bond in
accordance with Section 1404.11. Combined total thickness of
the Portland cement plaster, mortar and thin veneer brick
units shall be not less than 13/4". Interior side covered with one
layer of5/8"-thick Type X gypsum wallboard attached to studs
with 1" long No. 6 drywall screws at 12" on center.		 — — — 6
15. Exterior or
interior walls—
continued		 15-2.2d 35/8" No. 16 gage steel studs at 24" on center or 2" × 4" wood
studs at 24" on center. Metal lath attached to the exterior side
of studs with minimum 1" long No. 6 drywall screws at 6" on
center and covered with minimum3/4" thick Portland cement
plaster. Thin veneer brick units of clay or shale complying with
ASTM C1088, Grade TBS or better, installed in running bond in
accordance with Section 1404.11. Combined total thickness of
the Portland cement plaster, mortar and thin veneer brick
units shall be not less than 2". Interior side covered with two
layers of5/8"-thick Type X gypsum wallboard. Bottom layer
attached to studs with 1"-long No. 6 drywall screws at 24" on
center. Top layer attached to studs with 15/8"-long No. 6
drywall screws at 12" on center.		 — — 67/8 —
15. Exterior or
interior walls—
continued		 15-2.3d 35/8" No. 16 gage steel studs at 16" on center or 2" × 4" wood
studs at 16" on center. Where metal lath is used, attach to the
exterior side of studs with minimum 1"-long No. 6 drywall
screws at 6" on center. Brick units of clay or shale not less than
25/8" thick complying with ASTM C216 installed in accordance
with Section 1404.7 with a minimum 1" airspace. Interior side
covered with one layer of5/8"-thick Type X gypsum wallboard
attached to studs with 1"-long No. 6 drywall screws at 12" on
center.		 — — — 77/8
15. Exterior or
interior walls—
continued		 15-2.4d 35/8" No. 16 gage steel studs at 16" on center or 2" × 4" wood
studs at 16" on center. Where metal lath is used, attach to the
exterior side of studs with minimum 1"-long No. 6 drywall
screws at 6" on center. Brick units of clay or shale not less than
25/8" thick complying with ASTM C216 installed in accordance
with Section 1404.7 with a minimum 1" airspace. Interior side
covered with two layers of5/8"-thick Type X gypsum wallboard.
Bottom layer attached to studs with 1"-long No. 6 drywall
screws at 24" on center. Top layer attached to studs with 15/8"-
long No. 6 drywall screws at 12" on center.		 — — 81/2 —
16. Exterior walls
rated for fire
resistance from
the inside only in
accordance with
Section 705.5.		 16-1.1q 2" × 4" wood studs at 16" centers with double top plates,
single bottom plate; interior side covered with5/8" Type X
gypsum wallboard, 4’ wide, applied horizontally unblocked,
and fastened with 21/4" Type S drywall screws, spaced 12" on
center, wallboard joints covered with paper tape and joint
compound, fastener heads covered with joint compound.
Exterior covered with3/8" wood structural panels, applied
vertically, horizontal joints blocked and fastened with 6d
common nails (bright)—12" on center in the field, and 6" on
center panel edges. Cavity to be filled with 31/2" mineral wool
insulation. Rating established for exposure from interior side
only.		 — — — 41/2

7-54 2025 CALIFORNIA BUILDING CODE

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

FIRE AND SMOKE PROTECTION FEATURES

TABLE 721.1(2)—RATED FIRE-RESISTANCE PERIODS FOR VARIOUS WALLS AND PARTITIONSa, o, p—continued

MATERIAL ITEM
NUMBER		 CONSTRUCTION MINIMUM FINISHED THICKNESS FACE-TO-FACEb
(inches)		 MINIMUM FINISHED THICKNESS FACE-TO-FACEb
(inches)		 MINIMUM FINISHED THICKNESS FACE-TO-FACEb
(inches)		 MINIMUM FINISHED THICKNESS FACE-TO-FACEb
(inches)
MATERIAL ITEM
NUMBER		 CONSTRUCTION 4 hours 3 hours 2 hours 1 hour
16. Exterior walls
rated for fire
resistance from
the inside only in
accordance with
Section 705.5.—
continued		 16-1.2q 2" × 6" wood studs at 16" centers with double top plates,
single bottom plate; interior side covered with5/8" Type X
gypsum wallboard, 4’ wide, applied horizontally or vertically
with vertical joints over studs and fastened with 21/4" Type S
drywall screws, spaced 12" on center, wallboard joints
covered with paper tape and joint compound, fastener heads
covered with joint compound, exterior side covered with7/16"
wood structural panels fastened with 6d common nails
(bright) spaced 12" on center in the field and 6" on center
along the panel edges. Cavity to be filled with 51/2" mineral
wool insulation. Rating established from the gypsum-covered
side only.		 — — — 69/16
16. Exterior walls
rated for fire
resistance from
the inside only in
accordance with
Section 705.5.—
continued		 16-1.3q 2" × 6" wood studs at 16" centers with double top plates,
single bottom plates; interior side covered with5/8" Type X
gypsum wallboard, 4’ wide, applied vertically with all joints
over framing or blocking and fastened with 21/4" Type S
drywall screws spaced 7" on center. Joints to be covered with
tape and joint compound. Exterior covered with3/8" wood
structural panels, applied vertically with edges over framing or
blocking and fastened with 6d common nails (bright) at 12" on
center in the field and 6" on center on panel edges. R-19
mineral fiber insulation installed in stud cavity. Rating estab-
lished from the gypsum-covered side only.		 — — — 61/2
16. Exterior walls
rated for fire
resistance from
the inside only in
accordance with
Section 705.5.—
continued		 16-1.4q 2" × 6" wood studs at 24" centers with double top plates,
single bottom plates; interior side covered with5/8" Type X
gypsum wallboard, 4’ wide, applied vertically with all joints
over framing or blocking and fastened with 21/4" Type S
drywall screws spaced 7" on center. Joints covered with tape
and joint compound. Exterior covered with15/32" wood struc-
tural panels, applied vertically with edges over framing or
blocking and fastened with 6d common nails (bright) at 12" on
center in the field and 6" on center on panel edges. R-19 fiber-
glass insulation installed in stud cavity. Rating established
from the gypsum-covered side only.		 — — — 619/32

For SI: 1 inch = 25.4 mm, 1 square inch = 645.2 mm2, 1 cubic foot = 0.0283 m3.
a. Staples with equivalent holding power and penetration shall be permitted to be used as alternate fasteners to nails for attachment to wood framing.
b. Thickness shown for brick and clay tile is nominal thicknesses unless plastered, in which case thicknesses are net. Thickness shown for concrete masonry and clay masonry is
equivalent thickness defined in Section 722.3.1 for concrete masonry and Section 722.4.1.1 for clay masonry. Where all cells are solid grouted or filled with silicone-treated
perlite loose-fill insulation; vermiculite loose-fill insulation; or expanded clay, shale or slate lightweight aggregate, the equivalent thickness shall be the thickness of the block
or brick using specified dimensions as defined in Chapter 21. Equivalent thickness shall include the thickness of applied plaster and lath or gypsum wallboard, where
specified.
c. For units in which the net cross-sectional area of cored brick in any plane parallel to the surface containing the cores is not less than 75 percent of the gross cross-sectional
area measured in the same plane.
d. Shall be used for nonbearing purposes only.
e. For all of the construction with gypsum wallboard described in this table, gypsum base for veneer plaster of the same size, thickness and core type shall be permitted to be
substituted for gypsum wallboard, provided that attachment is identical to that specified for the wallboard, and the joints on the face layer are reinforced and the entire
surface is covered with not less than1/16-inch gypsum veneer plaster.
f. The fire-resistance time period for concrete masonry units meeting the equivalent thicknesses required for a 2-hour fire-resistance rating in Item 3, and having a thickness of
not less than 75/8 inches is 4 hours where cores that are not grouted are filled with silicone-treated perlite loose-fill insulation; vermiculite loose-fill insulation; or expanded
clay, shale or slate lightweight aggregate, sand or slag having a maximum particle size of3/8 inch.
g. The fire-resistance rating of concrete masonry units composed of a combination of aggregate types or where plaster is applied directly to the concrete masonry shall be
determined in accordance with ACI 216.1/TMS 216. Lightweight aggregates shall have a maximum combined density of 65 pounds per cubic foot.
h. See Note b. The equivalent thickness shall be permitted to include the thickness of cement plaster or 1.5 times the thickness of gypsum plaster applied in accordance with the
requirements of Chapter 25.
i. Concrete walls shall be reinforced with horizontal and vertical temperature reinforcement as required by Chapter 19.
j. Studs are welded truss wire studs with 0.18 inch (No. 7 B.W. gage) flange wire and 0.18 inch (No. 7 B.W. gage) truss wires.
k. Nailable metal studs consist of two channel studs spot welded back to back with a crimped web forming a nailing groove.
l. Wood structural panels shall be permitted to be installed between the fire protection and the wood studs on either the interior or exterior side of the wood frame assemblies
in this table, provided that the length of the fasteners used to attach the fire protection is increased by an amount not less than the thickness of the wood structural panel.
m.For studs with a slenderness ratio,le/d, greater than 33, the design stress shall be reduced to 78 percent of allowable_F′c._ For studs with a slenderness ratio,le/d, not exceeding
33, the design stress shall be reduced to 78 percent of the adjusted stress_F′c_ calculated for studs having a slenderness ratio_le/d_ of 33.
n. For properties of cooler or wallboard nails, see ASTM C514, ASTM C547 or ASTM F1667.
o. Generic fire-resistance ratings (those not designated as PROPRIETARY* in the listing) in the GA-600 shall be accepted as if herein specified.
p. NCMA TEK 5-8A shall be permitted for the design of fire walls.
q. The studs in this assembly can be designed without fire-related capacity reductions.

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

FIRE AND SMOKE PROTECTION FEATURES

TABLE 721.1(3)—MINIMUM PROTECTION FOR FLOOR AND ROOF SYSTEMS a, q

FLOOR OR ROOF
CONSTRUCTION		 ITEM
NUMBER		 CEILING CONSTRUCTION THICKNESS OF FLOOR OR ROOF
SLAB (inches)		 THICKNESS OF FLOOR OR ROOF
SLAB (inches)		 THICKNESS OF FLOOR OR ROOF
SLAB (inches)		 THICKNESS OF FLOOR OR ROOF
SLAB (inches)		 MINIMUM THICKNESS OF
CEILING (inches)		 MINIMUM THICKNESS OF
CEILING (inches)		 MINIMUM THICKNESS OF
CEILING (inches)		 MINIMUM THICKNESS OF
CEILING (inches)
FLOOR OR ROOF
CONSTRUCTION		 ITEM
NUMBER		 CEILING CONSTRUCTION **4 **
hours		 **3 **
hours		 **2 **
hours		 **1 **
hour		 **4 **
hours		 **3 **
hours		 **2 **
hours		 **1 **
hour
1. Siliceous
aggregate concrete		 1-1.1 Slab (ceiling not required). Minimum
cover over nonprestressed reinforce-
ment shall be not less than3/4".b		 7.0 6.2 5.0 3.5 — — — —
2. Carbonate
aggregate concrete		 2-1.1 2-1.1 6.6 5.7 4.6 3.2 — — — —
3. Sand-lightweight concrete 3-1.1 3-1.1 5.4 4.6 3.8 2.7 — — — —
4. Lightweight concrete 4-1.1 4-1.1 5.1 4.4 3.6 2.5 — — — —
5. Reinforced concrete 5-1.1 Slab with suspended ceiling of vermic-
ulite gypsum plaster over metal lath
attached to3/4" cold-rolled channels
spaced 12" on center. Ceiling located
6" minimum below joists.		 3 2 — — 1 3/4 — —
5. Reinforced concrete 5-2.1 5/8" Type X gypsum wallboardc
attached to 0.018 inch (No.25 carbon
sheet steel gage) by7/8" deep by 25/8"
hat-shaped galvanized steel channels
with 1"-long No. 6 screws. The chan-
nels are spaced 24" on center, span
35" and are supported along their
length at 35" intervals by 0.033" (No.
21 galvanized sheet gage) galvanized
steel flat strap hangers having formed
edges that engage the lips of the chan-
nel. The strap hangers are attached to
the side of the concrete joists with5/32"
by 11/4"-long power-driven fasteners.
The wallboard is installed with the
long dimension perpendicular to the
channels. End joints occur on channels
and supplementary channels are
installed parallel to the main channels,
12" each side, at end joint occur-
rences. The finished ceiling is located
approximately 12" below the soffit of
the floor slab.		 — — 21/2 — — — 5/8 —
6. Steel joists constructed
with a poured reinforced
concrete slab on metal lath
forms or steel form units.d, e		 6-1.1 Gypsum plaster on metal lath
attached to the bottom cord with
single No. 16 gage or doubled No. 18
gage wire ties spaced 6" on center.
Plaster mixed 1:2 for scratch coat, 1:3
for brown coat, by weight, gypsum-to-
sand aggregate for 2-hour system. For
3-hour system plaster is neat.		 — — 21/2 21/4 — — 3/4 5/8
6. Steel joists constructed
with a poured reinforced
concrete slab on metal lath
forms or steel form units.d, e		 6-2.1 Vermiculite gypsum plaster on metal
lath attached to the bottom chord
with single No. 16 gage or doubled
0.049-inch (No. 18 B.W. gage) wire ties
6" on center.		 — 2 — — — 5/8 — —
6. Steel joists constructed
with a poured reinforced
concrete slab on metal lath
forms or steel form units.d, e		 6-3.1 Cement plaster over metal lath
attached to the bottom chord of joists
with single No. 16 gage or doubled
0.049" (No. 18 B.W. gage) wire ties
spaced 6" on center. Plaster mixed 1:2
for scratch coat, 1:3 for brown coat for
1-hour system and 1:1 for scratch coat,
1:11/2 for brown coat for 2-hour
system, by weight, cement to sand.		 — — — 2 — — — 5/8
f

7-56 2025 CALIFORNIA BUILDING CODE

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

FIRE AND SMOKE PROTECTION FEATURES

TABLE 721.1(3)—MINIMUM PROTECTION FOR FLOOR AND ROOF SYSTEMS a, q—continued

FLOOR OR ROOF
CONSTRUCTION		 ITEM
NUMBER		 CEILING CONSTRUCTION THICKNESS OF FLOOR OR ROOF
SLAB (inches)		 THICKNESS OF FLOOR OR ROOF
SLAB (inches)		 THICKNESS OF FLOOR OR ROOF
SLAB (inches)		 THICKNESS OF FLOOR OR ROOF
SLAB (inches)		 MINIMUM THICKNESS OF
CEILING (inches)		 MINIMUM THICKNESS OF
CEILING (inches)		 MINIMUM THICKNESS OF
CEILING (inches)		 MINIMUM THICKNESS OF
CEILING (inches)
FLOOR OR ROOF
CONSTRUCTION		 ITEM
NUMBER		 CEILING CONSTRUCTION **4 **
hours		 **3 **
hours		 **2 **
hours		 **1 **
hour		 **4 **
hours		 **3 **
hours		 **2 **
hours		 **1 **
hour
6. Steel joists constructed
with a poured reinforced
concrete slab on metal lath
forms or steel form units.d, e
—continued		 6-4.1 Ceiling of5/8" Type X wallboardc
attached to7/8" deep by 25/8" by
0.021 inch (No. 25 carbon sheet steel
gage) hat-shaped furring channels
12" on center with 1"-long No. 6 wall-
board screws at 8" on center.
Channels wire tied to bottom chord
of joists with doubled 0.049 inch (No.
18 B.W. gage) wire or suspended
below joists on wire hangers.g		 — — 21/2 — — — 5/8 —
6. Steel joists constructed
with a poured reinforced
concrete slab on metal lath
forms or steel form units.d, e
—continued		 6-5.1 Wood-fibered gypsum plaster mixed
1:1 by weight gypsum to sand aggre-
gate applied over metal lath. Lath
tied 6" on center to3/4" channels
spaced 131/2" on center. Channels
secured to joists at each intersection
with two strands of 0.049 inch (No.
18 B.W. gage) galvanized wire.		 — — 21/2 — — — 3/4 —
7. Reinforced concrete slabs
and joists with hollow clay
tile fillers laid end to end in
rows 21/2" or more apart;
reinforcement placed
between rows and concrete
cast around and over tile.		 7-1.1 5/8" gypsum plaster on bottom of
floor or roof construction.		 — — 8h — — — 5/8 —
7. Reinforced concrete slabs
and joists with hollow clay
tile fillers laid end to end in
rows 21/2" or more apart;
reinforcement placed
between rows and concrete
cast around and over tile.		 7-1.2 None — — — 51/2
i		 — — — —
8. Steel joists constructed
with a reinforced concrete
slab on top poured on a1/2"-
deep steel deck.e		 8-1.1 Vermiculite gypsum plaster on metal
lath attached to3/4" cold-rolled chan-
nels with 0.049" (No. 18 B.W. gage)
wire ties spaced 6" on center.		 21/2
j		 — — — 3/ 4 — — —
9. 3"-deep cellular steel
deck with concrete slab on
top. Slab thickness
measured to top.		 9-1.1 Suspended ceiling of vermiculite
gypsum plaster base coat and vermic-
ulite acoustical plaster on metal lath
attached at 6" intervals to3/4" cold-
rolled channels spaced 12" on center
and secured to 11/2" cold-rolled chan-
nels spaced 36" on center with 0.065"
(No. 16 B.W. gage) wire. 11/2" channels
supported by No. 8 gage wire hangers
at 36" on center. Beams within enve-
lope and with a 21/2" airspace between
beam soffit and lath have a 4-hour
rating.		 21/2 — — — 11/8
k		 — — —
10. 11/2"-deep steel roof
deck on steel framing. Insu-
lation board, 30 pcf density,
composed of wood fibers
with cement binders of
thickness shown bonded to
deck with unified asphalt
adhesive. Covered with a
Class A or B roof covering.		 10-1.1 Ceiling of gypsum plaster on metal
lath. Lath attached to3/4" furring
channels with 0.049" (No. 18 B.W.
gage) wire ties spaced 6" on center.
3/4" channel saddle tied to 2" chan-
nels with doubled 0.065" (No. 16
B.W. gage) wire ties. 2"channels
spaced 36" on center suspended 2"
below steel framing and saddle tied
with 0.165" (No. 8 B.W. gage) wire.
Plaster mixed 1:2 by weight,
gypsum-to-sand aggregate.		 — — 17/8 1 — — 3/4
1		 3/4
1

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

FIRE AND SMOKE PROTECTION FEATURES

TABLE 721.1(3)—MINIMUM PROTECTION FOR FLOOR AND ROOF SYSTEMS a, q—continued

FLOOR OR ROOF
CONSTRUCTION		 ITEM
NUMBER		 CEILING CONSTRUCTION THICKNESS OF FLOOR OR ROOF
SLAB (inches)		 THICKNESS OF FLOOR OR ROOF
SLAB (inches)		 THICKNESS OF FLOOR OR ROOF
SLAB (inches)		 THICKNESS OF FLOOR OR ROOF
SLAB (inches)		 MINIMUM THICKNESS OF
CEILING (inches)		 MINIMUM THICKNESS OF
CEILING (inches)		 MINIMUM THICKNESS OF
CEILING (inches)		 MINIMUM THICKNESS OF
CEILING (inches)
FLOOR OR ROOF
CONSTRUCTION		 ITEM
NUMBER		 CEILING CONSTRUCTION **4 **
hours		 **3 **
hours		 **2 **
hours		 **1 **
hour		 **4 **
hours		 **3 **
hours		 **2 **
hours		 **1 **
hour
11. 11/2"-deep steel roof
deck on steel-framing wood
fiber insulation board, 17.5
pcf density on top applied
over a 15-lb asphalt-satu-
rated felt. Class A or B roof
covering.		 11-1.1 Ceiling of gypsum plaster on metal
lath. Lath attached to3/4" furring
channels with 0.049" (No. 18 B.W.
gage) wire ties spaced 6" on center.
3/4" channels saddle tied to 2" chan-
nels with doubled 0.065" (No. 16
B.W. gage) wire ties. 2" channels
spaced 36" on center suspended 2"
below steel framing and saddle tied
with 0.165" (No. 8 B.W. gage) wire.
Plaster mixed 1:2 for scratch coat
and 1:3 for brown coat, by weight,
gypsum-to-sand aggregate for 1-
hour system. For 2-hour system,
plaster mix is 1:2 by weight, gypsum-
to-sand aggregate.		 — — 11/2 1 — — 7/8
g		 3/4
1
12. 11/2" deep steel roof deck
on steel-framing insulation
of rigid board consisting of
expanded perlite and fibers
impregnated with integral
asphalt waterproofing;
density 9 to 12 pcf secured to
metal roof deck by1/2"-wide
ribbons of waterproof, cold-
process liquid adhesive
spaced 6" apart. Steel joist or
light steel construction with
metal roof deck, insulation,
and Class A or B built-up roof
covering.e		 12-1.1 Gypsum-vermiculite plaster on
metal lath wire tied at 6" intervals to
3/4" furring channels spaced 12" on
center and wire tied to 2" runner
channels spaced 32" on center.
Runners wire tied to bottom chord of
steel joists.		 — — 1 — — — 7/8 —
13. Double wood floor over
wood joists spaced 16" on
center.m, n		 13-1.1 Gypsum plaster over3/8" Type X
gypsum lath. Lath initially applied
with not less than four 11/8" by No. 13
gage by19/64" head plasterboard
blued nails per bearing. Continuous
stripping over lath along all joist lines.
Stripping consists of 3"-wide strips of
metal lath attached by 11/2" by No. 11
gage by1/2" head roofing nails spaced
6" on center. Alternate stripping
consists of 3"-wide 0.049" diameter
wire stripping weighing 1 pound per
square yard and attached by No. 16
gage by 11/2" by3/4" crown width
staples, spaced 4" on center. Where
alternate stripping is used, the lath
nailing shall consist of two nails at
each end and one nail at each inter-
mediate bearing. Plaster mixed 1:2 by
weight, gypsum-to-sand aggregate.		 — — — — — — — 7/8
13. Double wood floor over
wood joists spaced 16" on
center.m, n		 13-1.2 Cement or gypsum plaster on metal
lath. Lath fastened with 11/2" by No.
11 gage by7/16" head barbed shank
roofing nails spaced 5" on center.
Plaster mixed 1:2 for scratch coat
and 1:3 for brown coat, by weight,
cement to sand aggregate.		 — — — — — — — 5/8
13. Double wood floor over
wood joists spaced 16" on
center.m, n		 13-1.3 Perlite or vermiculite gypsum plaster
on metal lath secured to joists with
11/2" by No. 11 gage by7/16" head
barbed shank roofing nails spaced 5"
on center.		 — — — — — — — 5/8

7-58 2025 CALIFORNIA BUILDING CODE

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

FIRE AND SMOKE PROTECTION FEATURES

TABLE 721.1(3)—MINIMUM PROTECTION FOR FLOOR AND ROOF SYSTEMS a, q—continued

FLOOR OR ROOF
CONSTRUCTION		 ITEM
NUMBER		 CEILING CONSTRUCTION THICKNESS OF FLOOR OR ROOF
SLAB (inches)		 THICKNESS OF FLOOR OR ROOF
SLAB (inches)		 THICKNESS OF FLOOR OR ROOF
SLAB (inches)		 THICKNESS OF FLOOR OR ROOF
SLAB (inches)		 MINIMUM THICKNESS OF
CEILING (inches)		 MINIMUM THICKNESS OF
CEILING (inches)		 MINIMUM THICKNESS OF
CEILING (inches)		 MINIMUM THICKNESS OF
CEILING (inches)
FLOOR OR ROOF
CONSTRUCTION		 ITEM
NUMBER		 CEILING CONSTRUCTION **4 **
hours		 **3 **
hours		 **2 **
hours		 **1 **
hour		 **4 **
hours		 **3 **
hours		 **2 **
hours		 **1 **
hour
13. Double wood floor over
wood joists spaced 16" on
center.m, n—continued		 13-1.4 1/2" Type X gypsum wallboardc nailed
to joists with 5d coolero or wallboardo
nails at 6" on center. End joints of wall-
board centered on joists.		 — — — — — — — 1/2
14. Plywood stressed skin
panels consisting of5/8"-
thick interior C-D (exterior
glue) top stressed skin on 2"
× 6" nominal (minimum)
stringers. Adjacent panel
edges joined with 8d
common wire nails spaced
6" on center. Stringers
spaced 12" maximum on
center.		 14-1.1 1/2"-thick wood fiberboard weighing
15 to 18 pounds per cubic foot
installed with long dimension paral-
lel to stringers or3/8" C-D (exterior
glue) plywood glued and/or nailed to
stringers. Nailing to be with 5d
coolero or wallboardo nails at 12" on
center. Second layer of1/2" Type X
gypsum wallboardc applied with
long dimension perpendicular to
joists and attached with 8d coolero
or wallboardo nails at 6" on center at
end joints and 8" on center else-
where. Wallboard joints staggered
with respect to fiberboard joints.		 — — — — — — — 1
15. Vermiculite concrete slab
proportioned 1:4 (Portland
cement to vermiculite aggre-
gate) on a 11/2"-deep steel
deck supported on individu-
ally protected steel framing.
Maximum span of deck 6′-
10" where deck is less than
0.019 inch (No. 26 carbon
steel sheet gage) or greater.
Slab reinforced with 4" × 8"
0.109/0.083" (No.12/14 B.W.
gage) welded wire mesh.		 15-1.1 None — — — 3j — — — —
16. Perlite concrete slab
proportioned 1:6 (Portland
cement to perlite aggregate)
on a 11/4"-deep steel deck
supported on individually
protected steel framing. Slab
reinforced with 4" × 8"
0.109/0.083" (No.12/14 B.W.
gage) welded wire mesh.		 16-1.1 None — — — 31/2
j		 — — — —
17. Perlite concrete slab
proportioned 1:6 (Portland
cement to perlite aggregate)
on a9/16"-deep steel deck
supported by steel joists 4′
on center. Class A or B roof
covering on top.		 17-1.1 Perlite gypsum plaster on metal lath
wire tied to3/4" furring channels
attached with 0.065" (No. 16 B.W.
gage) wire ties to lower chord of
joists.		 — 2p 2p — — 7/8 3/4 —
18. Perlite concrete slab
proportioned 1:6 (Portland
cement to perlite aggregate)
on 11/4"-deep steel deck
supported on individually
protected steel framing. Maxi-
mum span of deck 6′-10"
where deck is less than 0.019"
(No. 26 carbon sheet steel
gage) and 8′-0" where deck is
0.019" (No. 26 carbon sheet
steel gage) or greater. Slab
reinforced with 0.042" (No. 19
B.W. gage) hexagonal wire
mesh. Class A or B roof cover-
ing on top.		 18-1.1 None — 21/4
p		 21/4
p		 — — — — —

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

FIRE AND SMOKE PROTECTION FEATURES

TABLE 721.1(3)—MINIMUM PROTECTION FOR FLOOR AND ROOF SYSTEMS a, q—continued

FLOOR OR ROOF
CONSTRUCTION		 ITEM
NUMBER		 CEILING CONSTRUCTION THICKNESS OF FLOOR OR ROOF
SLAB (inches)		 THICKNESS OF FLOOR OR ROOF
SLAB (inches)		 THICKNESS OF FLOOR OR ROOF
SLAB (inches)		 THICKNESS OF FLOOR OR ROOF
SLAB (inches)		 MINIMUM THICKNESS OF
CEILING (inches)		 MINIMUM THICKNESS OF
CEILING (inches)		 MINIMUM THICKNESS OF
CEILING (inches)		 MINIMUM THICKNESS OF
CEILING (inches)
FLOOR OR ROOF
CONSTRUCTION		 ITEM
NUMBER		 CEILING CONSTRUCTION **4 **
hours		 **3 **
hours		 **2 **
hours		 **1 **
hour		 **4 **
hours		 **3 **
hours		 **2 **
hours		 **1 **
hour
19. Floor and beam
construction consisting of
3"-deep cellular steel floor
unit mounted on steel
members with 1:4 (propor-
tion of Portland cement to
perlite aggregate) perlite-
concrete floor slab on top.		 19-1.1 Suspended envelope ceiling of perlite
gypsum plaster on metal lath attached
to3/4" cold-rolled channels, secured to
11/2" cold-rolled channels spaced 42"
on center supported by 0.203 inch (No.
6 B.W. gage) wire 36" on center. Beams
in envelope with 3" minimum airspace
between beam soffit and lath have a 4-
hour rating.		 2p — — — 1 l — — —
20. Perlite concrete propor-
tioned 1:6 (Portland cement
to perlite aggregate) poured
to1/8" thickness above top of
corrugations of 15/16"-deep
galvanized steel deck maxi-
mum span 8′-0" for 0.024"
(No. 24 galvanized sheet
gage) or 6′-0" for 0.019" (No.
26 galvanized sheet gage)
with deck supported by indi-
vidually protected steel
framing. Approved polysty-
rene foam plastic insulation
board having a flame spread
not exceeding 75 (1" to 4"
thickness) with vent holes
that approximate 3 percent of
the board surface area placed
on top of perlite slurry. A 2′ by
4′ insulation board contains
six 23/4" diameter holes.
Board covered with 21/4"
minimum perlite concrete
slab. Slab reinforced with
mesh consisting of 0.042"
(No.19 B.W. gage) galvanized
steel wire twisted together to
form 2" hexagons with
straight 0.065" (No. 16 B.W.
gage) galvanized steel wire
woven into mesh and spaced
3". Alternate slab reinforce-
ment shall be permitted to
consist of 4" × 8",
0.109/0.238" (No. 12/4 B.W.
gage), or 2" × 2", 0.083/0.083"
(No. 14/14 B.W. gage) welded
wire fabric. Class A or B roof
covering on top.		 20-1.1 None — — Varies — — — — —
21. Wood joists, wood I-
joists, floor trusses and flat
or pitched roof trusses
spaced a maximum 24" o.c.
with1/2" wood structural
panels with exterior glue
applied at right angles to
top of joist or top chord of
trusses with 8 d nails. The
wood structural panel thick-
ness shall be not less than
nominal1/2" nor less than
required by Chapter 23.		 21-1.1 Base layer5/8" Type X gypsum wall-
board applied at right angles to joist
or truss 24" o.c. with 11/4" Type S or
Type W drywall screws 24" o.c. Face
layer5/8" Type X gypsum wallboard
or veneer base applied at right
angles to joist or truss through base
layer with 17/8" Type S or Type W
drywall screws 12" o.c. at joints and
intermediate joist or truss. Face layer
Type G drywall screws placed 2"
back on either side of face layer end
joints, 12" o.c.		 — — — Varies — — — 11/4

7-60 2025 CALIFORNIA BUILDING CODE

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

FIRE AND SMOKE PROTECTION FEATURES

TABLE 721.1(3)—MINIMUM PROTECTION FOR FLOOR AND ROOF SYSTEMS a, q—continued

FLOOR OR ROOF
CONSTRUCTION		 ITEM
NUMBER		 CEILING CONSTRUCTION THICKNESS OF FLOOR OR ROOF
SLAB (inches)		 THICKNESS OF FLOOR OR ROOF
SLAB (inches)		 THICKNESS OF FLOOR OR ROOF
SLAB (inches)		 THICKNESS OF FLOOR OR ROOF
SLAB (inches)		 MINIMUM THICKNESS OF
CEILING (inches)		 MINIMUM THICKNESS OF
CEILING (inches)		 MINIMUM THICKNESS OF
CEILING (inches)		 MINIMUM THICKNESS OF
CEILING (inches)
FLOOR OR ROOF
CONSTRUCTION		 ITEM
NUMBER		 CEILING CONSTRUCTION **4 **
hours		 **3 **
hours		 **2 **
hours		 **1 **
hour		 **4 **
hours		 **3 **
hours		 **2 **
hours		 **1 **
hour
22. Steel joists, floor trusses
and flat or pitched roof
trusses spaced a maximum
24" o.c. with1/2" wood struc-
tural panels with exterior
glue applied at right angles
to top of joist or top chord of
trusses with No. 8 screws.
The wood structural panel
thickness shall be not less
than nominal1/2" nor less
than required by Chapter 23.		 22-1.1 Base layer5/8" Type X gypsum board
applied at right angles to steel fram-
ing 24" on center with 1" Type S dry
wall screws spaced 24" on center.
Face layer5/8" Type X gypsum board
applied at right angles to steel fram-
ing attached through base layer with
15/8" Type S dry wall screws 12" on
center at end joints and intermediate
joints and 11/2" Type G dry wall screws
12 inches on center placed 2" back on
either side of face layer end joints.
Joints of the face layer are offset 24"
from the joints of the base layer.		 — — — Varies — — — 11/4
23. Wood I-joist (minimum
joist depth 91/4" with a mini-
mum flange depth of 15/16"
and a minimum flange
cross-sectional area of 2.25
square inches) at 24" o.c.
spacing with a minimum 1 ×
4 (3/4" × 3.5"actual) ledger
strip applied parallel to and
covering the bottom of the
bottom flange of each
member, tacked in place. 2"
mineral wool insulation, 3.5
pcf (nominal) installed adja-
cent to the bottom flange of
the I-joist and supported by
the 1 × 4 ledger strip.		 23-1.1 1/2"-deep single-leg resilient channel
16" on center (channels doubled at
wallboard end joints), placed
perpendicular to the furring strip
and joist and attached to each joist
by 17/8" Type S drywall screws.5/8"
Type C gypsum wallboard applied
perpendicular to the channel with
end joints staggered not less than 4′
and fastened with 11/8" Type S
drywall screws spaced 7" on center.
Wallboard joints to be taped and
covered with joint compound.		 — — — Varies — — — 5/8
24. Wood I-joist (minimum I-
joist depth 91/4" with a mini-
mum flange depth of 11/2"
and a minimum flange
cross-sectional area of 5.25
square inches; minimum
web thickness of3/8") @ 24"
o.c., 11/2" mineral wool insu-
lation (2.5 pcf-nominal)
resting on hat-shaped
furring channels.		 24-1.1 Minimum 0.026" thick hat-shaped
channel 16" o.c. (channels doubled
at wallboard end joints), placed
perpendicular to the joist and
attached to each joist by 11/4" Type S
drywall screws.5/8" Type C gypsum
wallboard applied perpendicular to
the channel with end joints stag-
gered and fastened with 11/8" Type S
drywall screws spaced 12" o.c. in the
field and 8" o.c. at the wallboard
ends. Wallboard joints to be taped
and covered with joint compound.		 — — — Varies — — — 5/8
25. Wood I-joist (minimum I-
joist depth 91/4" with a mini-
mum flange depth of 11/2"
and a minimum flange
cross-sectional area of 5.25
square inches; minimum
web thickness of7/16") @ 24"
o.c., 11/2" mineral wool insu-
lation (2.5 pcf-nominal)
resting on resilient
channels.		 25-1.1 Minimum 0.019"-thick resilient chan-
nel 16" o.c. (channels doubled at
wallboard end joints), placed perpen-
dicular to the joist and attached to
each joist by 15/8" Type S drywall
screws.5/8" Type C gypsum wallboard
applied perpendicular to the channel
with end joints staggered and fastened
with 1" Type S drywall screws spaced
12" o.c. in the field and 8" o.c. at the
wallboard ends. Wallboard joints to be
taped and covered with joint
compound.		 — — — Varies — — — 5/8

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

FIRE AND SMOKE PROTECTION FEATURES

TABLE 721.1(3)—MINIMUM PROTECTION FOR FLOOR AND ROOF SYSTEMS a, q—continued

FLOOR OR ROOF
CONSTRUCTION		 ITEM
NUMBER		 CEILING CONSTRUCTION THICKNESS OF FLOOR OR ROOF
SLAB (inches)		 THICKNESS OF FLOOR OR ROOF
SLAB (inches)		 THICKNESS OF FLOOR OR ROOF
SLAB (inches)		 THICKNESS OF FLOOR OR ROOF
SLAB (inches)		 MINIMUM THICKNESS OF
CEILING (inches)		 MINIMUM THICKNESS OF
CEILING (inches)		 MINIMUM THICKNESS OF
CEILING (inches)		 MINIMUM THICKNESS OF
CEILING (inches)
FLOOR OR ROOF
CONSTRUCTION		 ITEM
NUMBER		 CEILING CONSTRUCTION **4 **
hours		 **3 **
hours		 **2 **
hours		 **1 **
hour		 **4 **
hours		 **3 **
hours		 **2 **
hours		 **1 **
hour
26. Wood I-joist (minimum I-
joist depth 91/4" with a mini-
mum flange thickness of
11/2" and a minimum flange
cross-sectional area of 2.25
square inches; minimum
web thick-ness of3/8") @ 24"
o.c.		 26-1.1 Two layers of1/2" Type X gypsum wall-
board applied with the long dimension
perpendicular to the I-joists with end
joints staggered. The base layer is
fastened with 15/8" Type S dry wall
screws spaced 12" o.c. and the face
layer is fastened with 2" Type S drywall
screws spaced 12" o.c. in the field and
8" o.c. on the edges. Face layer end
joints shall not occur on the same I-
joist as base layer end joints and edge
joints shall be offset 24"from base
layer joints. Face layer to also be
attached to base layer with 11/2" Type
G drywall screws spaced 8" o.c. placed
6" from face layer end joints. Face
layer wallboard joints to be taped and
covered with joint compound.		 — — — Varies — — — 1
27. Wood I-joist (minimum I-
joist depth 91/2" with a mini-
mum flange depth of 15/16"
and a minimum flange
cross-sectional area of 1.95
square inches; minimum
web thickness of3/8") @ 24"
o.c.		 27-1.1 Minimum 0.019" thick resilient chan-
nel 16" o.c. (channels doubled at
wallboard end joints), placed perpen-
dicular to the joist and attached to
each joist by 11/4" Type S drywall
screws. Two layers of1/2" Type X
gypsum wallboard applied with the
long dimension perpendicular to the
resilient channels with end joints stag-
gered. The base layer is fastened with
11/4" Type S drywall screws spaced 12"
o.c. and the face layer is fastened with
15/8" Type S drywall screws spaced 12"
o.c. Face layer end joints shall not
occur on the same I-joist as base layer
end joints and edge joints shall be
offset 24" from base layer joints. Face
layer to also be attached to base layer
with 11/2" Type G drywall screws
spaced 8" o.c. placed 6" from face
layer end joints. Face layer wallboard
joints to be taped and covered with
joint compound.		 — — — Varies — — — 1
28. Wood I-joist (minimum I-
joist depth 91/4" with a mini-
mum flange depth of 11/2"
and a minimum flange
cross-sectional area of 2.25
square inches; minimum
web thickness of3/8") @ 24"
o.c. Unfaced fiberglass insu-
lation or mineral wool
insulation is installed
between the I-joists
supported on the upper
surface of the flange by stay
wires spaced 12" o.c.		 28-1.1 Base layer of5/8" Type C gypsum
wallboard attached directly to I-
joists with 15/8" Type S drywall
screws spaced 12" o.c. with ends
staggered. Minimum 0.0179"-thick
hat-shaped7/8-inch furring channel
16" o.c. (channels doubled at wall-
board end joints), placed
perpendicular to the joist and
attached to each joist by 15/8" Type S
drywall screws after the base layer of
gypsum wallboard has been applied.
The middle and face layers of5/8"
Type C gypsum wallboard applied
perpendicular to the channel with
end joints staggered. The middle
layer is fastened with 1" Type S
drywall screws spaced 12" o.c. The
face layer is applied parallel to the
middle layer but with the edge joints
offset 24" from those of the middle
layer and fastened with 15/8" Type S
drywall screws 8" o.c. The joints shall
be taped and covered with joint
compound.		 — — — Varies — — 23/4 —

7-62 2025 CALIFORNIA BUILDING CODE

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

FIRE AND SMOKE PROTECTION FEATURES

TABLE 721.1(3)—MINIMUM PROTECTION FOR FLOOR AND ROOF SYSTEMS a, q—continued

FLOOR OR ROOF
CONSTRUCTION		 ITEM
NUMBER		 CEILING CONSTRUCTION THICKNESS OF FLOOR OR ROOF
SLAB (inches)		 THICKNESS OF FLOOR OR ROOF
SLAB (inches)		 THICKNESS OF FLOOR OR ROOF
SLAB (inches)		 THICKNESS OF FLOOR OR ROOF
SLAB (inches)		 MINIMUM THICKNESS OF
CEILING (inches)		 MINIMUM THICKNESS OF
CEILING (inches)		 MINIMUM THICKNESS OF
CEILING (inches)		 MINIMUM THICKNESS OF
CEILING (inches)
FLOOR OR ROOF
CONSTRUCTION		 ITEM
NUMBER		 CEILING CONSTRUCTION **4 **
hours		 **3 **
hours		 **2 **
hours		 **1 **
hour		 **4 **
hours		 **3 **
hours		 **2 **
hours		 **1 **
hour
29. Channel-shaped 18 gage
steel joists (minimum depth
8") spaced a maximum 24"
o.c. supporting tongue-and-
groove wood structural
panels (nominal minimum
3/4"-thick) applied perpen-
dicular to framing members.
Structural panels attached
with 15/8" Type S-12 screws
spaced 12" o.c.		 29-1.1 Base layer5/8" Type X gypsum board
applied perpendicular to bottom of
framing members with 11/8" Type S-
12 screws spaced 12" o.c. Second
layer5/8" Type X gypsum board
attached perpendicular to framing
members with 15/8" Type S-12 screws
spaced 12" o.c. Second layer joints
offset 24" from base layer. Third
layer5/8" Type X gypsum board
attached perpendicular to framing
members with 23/8" Type S-12 screws
spaced 12" o.c. Third layer joints
offset 12" from second layer joints.
Hat-shaped7/8-inch rigid furring
channels applied at right angles to
framing members over third layer
with two 23/8" Type S-12 screws at
each framing member. Face layer
5/8" Type X gypsum board applied at
right angles to furring channels with
11/8" Type S screws spaced 12" o.c.		 — — Varies — — — 33/8 —
30. Wood I-joist (minimum I-
joist depth 91/2" with a mini-
mum flange depth of 11/2"
and a minimum flange
cross-sectional area of 2.25
square inches; minimum
web thickness of3/8") @ 24"
o.c. Fiberglass insulation
placed between I-joists
supported by the resilient
channels.		 30-1.1 Minimum 0.019"-thick
resilient channel 16" o.c. (channels
doubled at wallboard end joints),
placed perpendicular to the joists
and attached to each joist by 11/4"
Type S dry wall screws. Two layers of
1/2" Type X gypsum wallboard
applied with the long dimension
perpendicular to the resilient chan-
nels with end joints staggered. The
base layer is fastened with 11/4" Type
S drywall screws spaced 12" o.c. and
the face layer is fastened with 15/8"
Type S drywall screws spaced 12"
o.c. Face layer end joints shall not
occur on the same I-joist as base
layer end joints and edge joints shall
be offset 24" from base layer joints.
Face layer to be attached to base
layer with 11/2" Type G drywall
screws spaced 8" o.c. placed 6" from
face layer end joints. Face layer wall-
board joints to be taped and covered
with joint compound.		 — — — Varies — — — 1

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

FIRE AND SMOKE PROTECTION FEATURES

TABLE 721.1(3)—MINIMUM PROTECTION FOR FLOOR AND ROOF SYSTEMS a, q—continued

FLOOR OR ROOF
CONSTRUCTION		 ITEM
NUMBER		 CEILING CONSTRUCTION THICKNESS OF FLOOR OR ROOF
SLAB (inches)		 THICKNESS OF FLOOR OR ROOF
SLAB (inches)		 THICKNESS OF FLOOR OR ROOF
SLAB (inches)		 THICKNESS OF FLOOR OR ROOF
SLAB (inches)		 MINIMUM THICKNESS OF
CEILING (inches)		 MINIMUM THICKNESS OF
CEILING (inches)		 MINIMUM THICKNESS OF
CEILING (inches)		 MINIMUM THICKNESS OF
CEILING (inches)
FLOOR OR ROOF
CONSTRUCTION		 ITEM
NUMBER		 CEILING CONSTRUCTION **4 **
hours		 **3 **
hours		 **2 **
hours		 **1 **
hour		 **4 **
hours		 **3 **
hours		 **2 **
hours		 **1 **
hour
31. Wood I-joist (minimum I-
joist depth 91/4" with a mini-
mum flange thickness of
11/2" and a minimum flange
cross sectional area of 2.25
square inches; minimum
web thickness of3/8") @ 24"
o.c.		 31- 1.1 Two layers of1/2" Type C gypsum
wallboard applied with the long
dimension perpendicular to the I-
joists with end joints staggered. The
base layer is fastened with 1" Type S
drywall screws spaced 12" o.c. and
the face layer is fastened with 15/8"
Type S drywall screws spaced 12"
o.c. in the field and 8" o.c. on the
edges. Face layer edge joints shall
not occur on the same I-joist as base
layer end joints and edge joints shall
be offset 24" from base layer joints.
End joints centered on bottom
flange of I-joists and offset a mini-
mum of 48" from those of base layer.
Face layer to also be attached to
base layer with 11/2" Type G drywall
screws spaced 8" o.c. with a 4” stag-
ger, placed 6" from face layer end
joints. Face layer wallboard joints
taped and covered with joint
compound. Screw heads covered
with joint compound.		 — — Varies — — — — —

For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound = 0.454 kg, 1 cubic foot = 0.0283 m3, 1 pound per square inch = 6.895 kPa, 1 pound per linear foot = 1.4882 kg/m.
a. Staples with equivalent holding power and penetration shall be permitted to be used as alternate fasteners to nails for attachment to wood framing.
b. Where the slab is in an unrestrained condition, minimum reinforcement cover shall be not less than 15/ 8 inches for 4 hours (siliceous aggregate only); 11/4 inches for 4 and 3
hours; 1 inch for 2 hours (siliceous aggregate only); and3/4 inch for all other restrained and unrestrained conditions.
c. For all of the construction with gypsum wallboard described in this table, gypsum base for veneer plaster of the same size, thickness and core type shall be permitted to be
substituted for gypsum wallboard, provided that attachment is identical to that specified for the wallboard, and the joints on the face layer are reinforced and the entire
surface is covered with not less than1/16-inch gypsum veneer plaster.
d. Slab thickness over steel joists measured at the joists for metal lath form and at the top of the form for steel form units.
e.
(a) The maximum allowable stress level for H-Series joists shall not exceed 22,000 psi.
(b) The allowable stress for K-Series joists shall not exceed 26,000 psi, the nominal depth of such joist shall be not less than 10 inches and the nominal joist weight shall be not
less than 5 pounds per linear foot.
f. Cement plaster with 15 pounds of hydrated lime and 3 pounds of approved additives or admixtures per bag of cement.
g. Gypsum wallboard ceilings attached to steel framing shall be permitted to be suspended with 11/2-inch cold-formed carrying channels spaced 48 inches on center, that are
suspended with No. 8 SWG galvanized wire hangers spaced 48 inches on center. Cross-furring channels are tied to the carrying channels with No. 18 SWG galvanized wire hang-
ers spaced 48 inches on center. Cross-furring channels are tied to the carrying channels with No. 18 SWG galvanized wire (double strand) and spaced as required for direct
attachment to the framing. This alternative is applicable to those steel framing assemblies recognized under Note q.
h. Six-inch hollow clay tile with 2-inch concrete slab above.
i. Four-inch hollow clay tile with 11/2-inch concrete slab above.
j. Thickness measured to bottom of steel form units.
k. Five-eighths inch of vermiculite gypsum plaster plus1/2 inch of approved vermiculite acoustical plastic.
l. Furring channels spaced 12 inches on center.
m.Double wood floor shall be permitted to be either of the following:
(a) Subfloor of 1-inch nominal boarding, a layer of asbestos paper weighing not less than 14 pounds per 100 square feet and a layer of 1-inch nominal tongue-and-groove finished
flooring.
(b) Subfloor of 1-inch nominal tongue-and-groove boarding or15/32-inch wood structural panels with exterior glue and a layer of 1-inch nominal tongue-and-groove finished floor-
ing or19/32-inch wood structural panel finish flooring or a layer of Type I Grade M-1 particleboard not less than5/8-inch thick.
n. The ceiling shall be permitted to be omitted over unusable space, and flooring shall be permitted to be omitted where unusable space occurs above.
o. For properties of cooler or wallboard nails, see ASTM C514, ASTM C547 or ASTM F1667.
p. Thickness measured on top of steel deck unit.
q. Generic fire-resistance ratings (those not designated as PROPRIETARY* in the listing) in the GA-600 shall be accepted as if herein specified.

721.1.1 Thickness of protective coverings. The thickness of fire-resistant materials required for protection of structural members shall be not less than set forth in Table 721.1(1), except as modified in this section. The figures shown shall be the net thickness of the protecting materials and shall not include any hollow space in back of the protection.

721.1.2 Unit masonry protection. Where required, metal ties shall be embedded in bed joints of unit masonry for protection of steel columns. Such ties shall be as set forth in Table 721.1(1) or be equivalent thereto.

721.1.3 Reinforcement for cast-in-place concrete column protection. Cast-in-place concrete protection for steel columns shall be reinforced at the edges of such members with wire ties of not less than 0.18 inch (4.6 mm) in diameter wound spirally around the columns on a pitch of not more than 8 inches (203 mm) or by equivalent reinforcement.

721.1.4 Plaster application. The finish coat is not required for plaster protective coatings where those coatings comply with the design mix and thickness requirements of Tables 721.1(1), 721.1(2) and 721.1(3).

7-64 2025 CALIFORNIA BUILDING CODE

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

FIRE AND SMOKE PROTECTION FEATURES

721.1.5 Bonded prestressed concrete tendons. For members having a single tendon or more than one tendon installed with equal concrete cover measured from the nearest surface, the cover shall be not less than that set forth in Table 721.1(1). For members having multiple tendons installed with variable concrete cover, the average tendon cover shall be not less than that set forth in Table 721.1(1), provided that:

  1. The clearance from each tendon to the nearest exposed surface is used to determine the average cover.
  2. The clear cover for individual tendons shall not be less than one-half of that set forth in Table 721.1(1). A minimum cover of [3] / 4 inch (19.1 mm) for slabs and 1 inch (25 mm) for beams is required for any aggregate concrete.
  3. For the purpose of establishing a fire-resistance rating, tendons having a clear covering less than that set forth in Table 721.1(1) shall not contribute more than 50 percent of the required ultimate moment capacity for members less than 350 square inches (0.226 m [2] ) in cross-sectional area and 65 percent for larger members. For structural design purposes, however, tendons having a reduced cover are assumed to be fully effective.

721.2 Cellular concrete. [HCD 1 & HCD 2]

721.2.1 Use and application. [HCD 1 & HCD 2] Controlled-density cellular concrete, when used or applied, shall be in accordance with the use of materials in Bulletin No. 65 of the Federal Housing Administration, United States Department of Housing and Urban Development.

Exceptions: 1. Regardless of the provisions of Subsections 3.2, 3.3, 3.4 and 3.6 in Section 3, Bulletin No. 65 provisions relating to propor- tioning, mixing and testing, in the following shall apply to this chapter. 1.1. Field-control weighings for control of the wet-unit weight shall be made. The design wet-unit weight for field control of the concrete shall be based on previously established data for the relation between the wet-unit weight and the air-dry-unit weight at 28 days for the mix being placed. Field-control weighings for determining the wet-unit weight shall be made at the mixer discharge and at the point of deposit. There should be one pair of weighings per batch for batch-type mixers unless equipment is provided with scales allowing the operator to adequately weigh materials. For continuous weight-instrumented batch mixers, there should be one pair of weighings per 10 cubic yards (7.65 m3). The gain in unit weight between the mixer discharge and point of deposit shall not exceed 5 percent. The wet-unit weight at the point of deposit of the concrete shall not exceed plus 5 percent of the design wet-unit weight. A variation exceeding plus 5 percent of the design wet-unit weight shall require a modification of the mix proportions, a change of materials or a change in the mixing procedure.

in unit weight between the mixer discharge and point of deposit shall not exceed 5 percent._ The wet-unit weight at the point of deposit of the concrete shall not exceed plus 5 percent of the design wet-unit weight. A variation exceeding plus 5 percent of the design wet-unit weight shall require a modification of the mix proportions, a change of materials or a change in the mixing procedure.

1.2. When tests are required by the enforcing agency, they shall be performed in the following manner: Two test cylinders, for compressive strength tests, shall be made for each 8,000 square feet (743 m [2] ) of surface area placed. A minimum of two test cylinders shall be made each day. Each strength test result shall be the average of two cylinders from the same sample tested at 28 days or at a specified earlier date. 1.3. The minimum air-dry density shall be 90 pounds per cubic foot (1,440 kg/m3). The minimum design compressive strength shall be 1,000 psi (6,890 kPa) when the curing procedure specified herein is applied. The minimum design compressive strength shall be 1,250 psi (8,619 kPa) if the slab is placed in a covered area of a building and a specified curing medium is not applied. The specified design compressive strength shall be increased 20 percent when the specified strength is greater than 1,000 psi (6,890 kPa) and the slab is placed in a covered area of a building and a specified curing medium is not applied. 1.4. The cellular concrete shall be sampled at the point of deposit in accordance with the applicable procedures of ASTM C172, Sampling Fresh Concrete. Cylinder molds shall be either 3 inches by 6 inches (76 mm by 152 mm) or 6 inches by 12 inches (152 mm by 305 mm). Lightly tap the sides of the mold with a rubber hammer while filling the mold instead of rodding the mix. Moist cure the specimens for seven days at 73.4°F (40.8°C) plus or minus 3°F (1.7°C). At the age of seven days, remove the specimens from the moist condition and store in a temperature of 73.4°F (40.8°C) plus or minus 3°F (1.7°C) and a relative humidity of 50 plus or minus 10 percent for 21 days; remove and air dry until the time of test at 28 days. The compressive strength test shall be in accordance with ASTM C39, Compressive Strength of Cylindrical Concrete Specimens. Determine the air-dry-unit weight at 28 days. 2. Regardless of the provisions of Subsections 4.1 and 4.2 in Section 4 of Bulletin No. 65, relating to placing, finishing and curing, the following shall apply to these regulations. 2.1. The concrete shall be placed, finished and cured to produce a level, smooth surface. The concrete shall be placed in a single layer to a minimum thickness of 1 [1] / 2 inches (38 mm). The deviation from a plan shall not exceed [1] / 4 inch (6 mm) in any 10 feet (3048 mm). The final finish of the concrete shall be suitable for the applica- tion of the specified wear- resistant covering. Cracks wider than [1] / 8 inch (3 mm) shall be repaired. 2.2. Install a water-resistant membrane between wood or plywood subfloors and the cellular concrete to prevent leakage of the concrete and wetting of the subfloor. The membrane shall consist of waterproof paper or plastic sheets conforming to ASTM C171, Sheet Materials for Curing Concrete, or Type 15 roofing felt conform- ing to ASTM D226, D250 or D227, or Federal Specification UUB790, Building Paper Vegetable Fiber: (Kraft, Waterproofed, Water Repellent and Fire-resistant) Type 1, Grade B. The sheets shall be securely fastened to the subfloor.

oor. The membrane shall consist of waterproof paper or_ plastic sheets conforming to ASTM C171, Sheet Materials for Curing Concrete, or Type 15 roofing felt conform- ing to ASTM D226, D250 or D227, or Federal Specification UUB790, Building Paper Vegetable Fiber: (Kraft, Waterproofed, Water Repellent and Fire-resistant) Type 1, Grade B. The sheets shall be securely fastened to the subfloor.

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

FIRE AND SMOKE PROTECTION FEATURES

3. Regardless of the provisions of Subsections 6.1 and 6.2 in Section 6, of Bulletin No. 65, relating to applicator qualifica- tions and warranty, these subsections are omitted from this chapter.

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▸ Contents — 2025 California Building Code (Title 24, Part 2)
2025 California Building Code (Title 24, Part 2)
  1. Chapter 1 — ADMINISTRATION
  2. Chapter 2 — DEFINITIONS
  3. Chapter 3 — OCCUPANCY CLASSIFICATION AND USE
  4. Chapter 4 — SPECIAL DETAILED REQUIREMENTS BASED ON OCCUPANCY A…
  5. Chapter 5 — GENERAL BUILDING HEIGHTS AND AREAS
  6. Chapter 6 — TYPES OF CONSTRUCTION
  7. ▸ Chapter 7 — FIRE AND SMOKE PROTECTION FEATURES
    Overview
    1. Section 701 — GENERAL
    2. Section 702 — MULTIPLE-USE FIRE ASSEMBLIES
    3. Section 703 — FIRE-RESISTANCE RATINGS AND FIRE TESTS
    4. Section 704 — FIRE-RESISTANCE RATING OF STRUCTURAL MEMBERS
    5. Section 705 — EXTERIOR WALLS
    6. Section 706 — FIRE WALLS
    7. Section 707 — FIRE BARRIERS
    8. Section 708 — FIRE PARTITIONS
    9. Section 709 — SMOKE BARRIERS
    10. Section 710 — SMOKE PARTITIONS
    11. Section 711 — FLOOR AND ROOF ASSEMBLIES
    12. Section 712 — VERTICAL OPENINGS
    13. Section 713 — SHAFT ENCLOSURES
    14. Section 714 — PENETRATIONS
    15. Section 715 — JOINTS AND VOIDS
    16. Section 716 — OPENING PROTECTIVES
    17. Section 717 — DUCTS AND AIR TRANSFER OPENINGS
    18. Section 718 — CONCEALED SPACES
    19. Section 719 — FIRE-RESISTANCE REQUIREMENTS FOR PLASTER
    20. Section 720 — THERMAL- AND SOUND-INSULATING MATERIALS
    21. Section 721 — PRESCRIPTIVE FIRE RESISTANCE
    22. Section 722 — CALCULATED FIRE RESISTANCE
  8. Chapter 7A — MATERIALS AND CONSTRUCTION METHODS FOR EXTERIOR W…
  9. Chapter 8 — INTERIOR FINISHES
  10. Chapter 9 — FIRE PROTECTION AND LIFE SAFETY SYSTEMS
  11. Chapter 10 — MEANS OF EGRESS
  12. Chapter 11 — RESERVED
  13. Chapter 11A — HOUSING ACCESSIBILITY
  14. Chapter 11B — ACCESSIBILITY TO PUBLIC BUILDINGS, PUBLIC ACCOMM…
  15. Chapter 12 — INTERIOR ENVIRONMENT
  16. Chapter 13 — ENERGY EFFICIENCY
  17. Chapter 14 — EXTERIOR WALLS
  18. Chapter 15 — ROOF ASSEMBLIES AND ROOFTOP STRUCTURES
  19. Chapter 16 — STRUCTURAL DESIGN
  20. Chapter 16A — STRUCTURAL DESIGN
  21. Chapter 17 — SPECIAL INSPECTIONS AND TESTS
  22. Chapter 17A — SPECIAL INSPECTIONS AND TESTS
  23. Chapter 18 — SOILS AND FOUNDATIONS
  24. Chapter 18A — SOILS AND FOUNDATIONS
  25. Chapter 19 — CONCRETE
  26. Chapter 19A — CONCRETE
  27. Chapter 20 — ALUMINUM
  28. Chapter 21 — MASONRY
  29. Chapter 21A — MASONRY
  30. Chapter 22 — STEEL
  31. Chapter 22A — STEEL
  32. Chapter 23 — WOOD
  33. Chapter 24 — GLASS AND GLAZING
  34. Chapter 25 — GYPSUM PANEL PRODUCTS AND PLASTER
  35. Chapter 26 — PLASTIC
  36. Chapter 27 — ELECTRICAL
  37. Chapter 28 — MECHANICAL SYSTEMS
  38. Chapter 29 — PLUMBING SYSTEMS
  39. Chapter 30 — ELEVATORS AND CONVEYING SYSTEMS
  40. Chapter 31 — SPECIAL CONSTRUCTION
  41. Chapter 31A — SYSTEMS FOR WINDOW CLEANING OR EXTERIOR BUILDING…
  42. Chapter 31B — PUBLIC POOLS
  43. Chapter 31C — RADIATION
  44. Chapter 31D — FOOD ESTABLISHMENTS
  45. Chapter 31F — MARINE OIL TERMINALS
  46. Chapter 32 — ENCROACHMENTS INTO THE PUBLIC RIGHT-OF-WAY
  47. Chapter 33 — SAFEGUARDS DURING CONSTRUCTION
  48. Chapter 34 — RESERVED
  49. Chapter 35 — REFERENCED STANDARDS
  50. Appendix A — EMPLOYEE QUALIFICATIONS
  51. Appendix B — BOARD OF APPEALS
  52. Appendix C — GROUP U—AGRICULTURAL BUILDINGS
  53. Appendix D — FIRE DISTRICTS
  54. Appendix E — RESERVED
  55. Appendix F — RODENTPROOFING
  56. Appendix G — FLOOD-RESISTANT CONSTRUCTION
  57. Appendix H — SIGNS
  58. Appendix I — PATIO COVERS
  59. Appendix J — GRADING
  60. Appendix K — GROUP R-3 AND GROUP R-3.1 OCCUPANCIES PROTECTED B…
  61. Appendix L — EARTHQUAKE RECORDING INSTRUMENTATION
  62. Appendix M — TSUNAMI-GENERATED FLOOD HAZARDS
  63. Appendix N — REPLICABLE BUILDINGS
  64. Appendix O — PERFORMANCE-BASED APPLICATION
  65. Appendix P — SLEEPING LOFTS
  66. Appendix Q — EMERGENCY HOUSING

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