Fire Rated Wood Floor and Wall Assemblies
Building Code Requirements
For occupancies such as stores, apartments, offices, and other commercial and industrial uses, building codes commonly require floor/ceiling and wall assemblies to be fire-resistance rated in accordance with standard fire tests.

    Depending on the application, wall assemblies may need to be rated either from one side or both sides. For specific exterior wall applications, the 2000 International Building Code (IBC), the 1999 National Building Code (NBC), and the 1999 Standard Building Code (SBC) allow wood-frame, wood-sided walls to be tested for exposure to fire from the inside only. Rating for both interior and exterior exposure is only required when the wall has a fire separation distance of less than 5 feet. Code recognition of one and two-hour wood-frame wall systems is also predicated on successful fire and hose stream testing in accordance with ASTM E119, Standard Test Methods for Fire Tests of Building Construction Materials.

Fire Tested Assemblies
Fire-rated wood-frame assemblies can be found in a number of sources including the IBC, Underwriters Laboratories (UL) Fire Resistance 
Directory, Intertek Testing Services' Directory of Listed Products, and the Gypsum Association's Fire Resistance Design Manual. The American Forest & Paper Association (AF&PA) and its members have tested a number of wood-frame fire-rated assemblies. Descriptions of these successfully tested assemblies are provided in Table 1 for one-hour rated wall assemblies, Table 2 for two-hour rated wall assemblies, Table 3 for one-hour rated floor/ceiling assemblies, and Table 4 for two-hour rated floor/ceiling assemblies. Additional tests are being conducted and the Tables will be updated periodically.   Conclusions
Wood-frame assemblies are used in architectural designs because of their adaptability to style preferences, ease and economies of construction, and energy-saving performance.


 

 

 



Table 1: One-Hour Fire-Rated Loadbearing Wood-Frame Wall Assemblies
Assemblies Rated From Both Sides
Studs
Insulation
Sheathing on Both Sides
Fasteners
Details
2x4 @ 16" o.c. 3½" mineral wool batts 5/8" Type X Gypsum Wallboard (H) 2¼" #6 Type S drywall screws @ 12" o.c.
WS4-1.1
2x6 @ 16" o.c. (none) 5/8" Type X Gypsum Wallboard (H) 2¼" #6 Type S drywall screws @ 7" o.c.
WS6-1.1
2x6 @ 16" o.c. 5½" mineral wool batts 5/8" Type X Gypsum Wallboard (H) 2¼" #6 Type S drywall screws @ 12" o.c.
WS6-1.2
2x6 @ 16" o.c. R-19 fiberglass insulation 5/8" Type X Gypsum Wallboard (V) 2¼" #6 Type S drywall screws @ 12" o.c.
WS6-1.4
Assemblies Rated From One Side (Fire on Interior Only)
Studs
Insulation
Sheathing
Fasteners
 
2x4 @ 16" o.c. 3½" mineral wool batts
I
5/8" Type X Gypsum Wallboard (H) 2¼" #6 Type S drywall screws @ 12" o.c.
WS4-1.2
E
3/8" wood structural panels (V) 6d common nails @ 6" edges/12" field
2x4 @ 16" o.c. 4 mil polyethylene 
3½" mineral wool batts
I
5/8" Type X Gypsum Wallboard (V) 6d cement coated box nails @ 7" o.c. 
WS4-1.3
E
½" fiberboard (V) 1½" roofing nails @ 3" edges/6" field
3/8" hardboard shiplapped panel siding 8d galv. nails @ 4" edges/8" field
2x6 @ 16" o.c. 5½" mineral wool batts
I
5/8" Type X Gypsum Wallboard (H) 2¼" #6 Type S drywall screws @ 12" o.c.
WS6-1.3
E
7/16" wood structural panels (V) 6d common nails @ 6" edges/12" field
2x6 @ 16" o.c. R-19 fiberglass insulation
I
5/8" Type X Gypsum Wallboard (V) 2¼" #6 Type S drywall screws @ 12" o.c.
WS6-1.5
E
3/8" wood structural panels (V) 6d common nails @ 6" edges/12" field
H- applied horizontally with vertical joints over studs                       I- Interior sheathing
V- applied vertically with vertical joints over studs                           E- Exterior sheathing


Table 2: Two-Hour Fire-Rated Loadbearing Wood-Frame Wall Assemblies
Assemblies Rated From Both Sides
Studs
Insulation
Sheathing on Both Sides
Fasteners
Details
2x6 @ 24" o.c. 5½" mineral wool batts
B
5/8" Type X Gypsum Wallboard (H) 2¼" #6 Type S drywall screws @ 24" o.c.
WS6-2.1
F
5/8" Type X Gypsum Wallboard (H) 2¼" #6 Type S drywall screws @ 8" o.c.
H- applied horizontally with vertical joints over studs
B- Base layer sheathing                                                                F- Face layer sheathing


















Table 3: One-Hour Fire-Rated Wood Floor/Ceiling Assemblies
Wood I-Joist Assemblies
Joists
Insulation
Furring
Ceiling Sheathing
Fasteners
Details
I-joists @ 24" o.c.
    Min. flange thickness: 1-1/2"
    Min. flange area: 5.25 sq. in.
    Min. web thickness: 3/8"
    Min. I-joist depth: 9-1/4"		 1-1/2"  mineral wool batts
(2.5 pcf - nominal)
Resting on hat-shaped channels		 Hat-shaped
channels		 F 5/8" Type C Gypsum Wallboard 1-1/8" Type S drywall screws @ 12" o.c.
see fastening details)
WIJ-1.1
I-joists @ 24" o.c.
    Min. flange thickness: 1-1/2"
    Min. flange area: 5.25 sq. in.
    Min. web thickness: 7/16"
    Min. I-joist depth: 9-1/4"		 1-1/2"  mineral wool batts
(2.5 pcf - nominal)
Resting on resilient channels		 Resilient
channels		 F 5/8" Type C Gypsum Wallboard 1" Type S drywall screws @ 8" o.c.
(see fastening details)
WIJ-1.2
I-joists @ 24" o.c.
    Min. flange thickness: 1-5/16"
    Min. flange area: 2.25 sq. in.
    Min. web thickness: 3/8"
    Min. I-joist depth: 9-1/4"		 2"  mineral wool batts
(3.5 pcf - nominal)
Resting on 1x4 setting strips		 Resilient
channels		 F 5/8" Type C Gypsum Wallboard 1-1/8" Type S drywall screws @ 7" o.c.
(see fastening details)
WIJ-1.3
I-joists @ 24" o.c.
    Min. flange thickness: 1-1/2"
    Min. flange area: 3.45 sq. in.
    Min. web thickness: 3/8"
    Min. I-joist depth: 9-1/4"		 1"  mineral wool batts
(6 pcf - nominal)
Resting on hat-shaped channels
under I-joist bottom flange		 Hat-shaped
channels
supported by
CSC clips		 F 1/2" Type C Gypsum Wallboard 1" Type S drywall screws @ 12" o.c.
(see fastening details)
WIJ-1.4
I-joists @ 24" o.c.
    Min. flange thickness: 1-1/2"
    Min. flange area: 2.25 sq. in.
    Min. web thickness: 3/8"
    Min. I-joist depth: 9-1/4"
(none)
(none)
B 1/2" Type X Gypsum Wallboard 1-5/8" Type S drywall screws @ 12" o.c.
WIJ-1.5
F 1/2" Type X Gypsum Wallboard 2" Type S drywall screws @ 12" o.c.
1-1/2" Type G drywall screws @ 8" o.c.
(see fastening details)
I-joists @ 24" o.c.
    Min. flange thickness: 1-5/16"
    Min. flange area: 1.95 sq. in.
    Min. web thickness: 3/8"
    Min. I-joist depth: 9-1/2"
(optional)
Resilient
channels		 B 1/2" Type X Gypsum Wallboard 1-1/4" Type S drywall screws @ 12" o.c.
WIJ-1.6
F 1/2" Type X Gypsum Wallboard 1-5/8" Type S drywall screws @ 12" o.c.
1-1/2" Type G drywall screws @  8" o.c.
(see fastening details)
B- Base layer sheathing                                                                F- Face layer sheathing


Table 4: Two-Hour Fire-Rated Wood Floor/Ceiling Assemblies
Wood I-Joist Assemblies
Joists
Insulation
 Furring 
Ceiling Sheathing
Fasteners
Details
I-joists @ 24" o.c.
    Min. flange thickness: 1-1/2"
    Min. flange area: 2.25 sq. in.
    Min. web thickness: 3/8"
    Min. I-joist depth: 9-1/4"		 3-1/2" fiberglass insulation

Supported by stay wires spaced 
12" o.c.
(none)
B 5/8" Type C Gypsum Wallboard 1-5/8" Type S drywall screws @ 12" o.c.
WIJ-2.1
Hat-shaped
channels		 M 5/8" Type C Gypsum Wallboard 1" Type S drywall screws @ 12" o.c.
F 5/8" Type C Gypsum Wallboard 1-5/8" Type S drywall screws @ 8" o.c.
(see fastening details)
B- Base layer sheathing  (direct attached)                                      M- Middle layer sheathing                                   F- Face layer sheathing




While every effort has been made to insure the accuracy of the information presented, the American Forest & Paper Association and its members do not assume responsibility for a particular design prepared from this publication. Copyright © 2002-2007  American Forest & Paper Association, Inc.  

February 2007 Revisions