Fire Walls
To facilitate the fire wall design process, numerous associations publish wall design
configurations meeting various fire criteria. Examples of these publications are
GA-600-2003 Fire Resistance Design Manual published by the Gypsum Association, Fire
Resistance 2003 by Underwriters Laboratories Inc. and others. By containing common
wall configurations, this saves the architect and/or engineer time in selecting the
wall assembly to meet the needs compared to the calculation time under provisions of
the IBC. This does not mean that alternative approaches to evaluating and selecting
materials for fire wall construction cannot be considered.
The following is contained in the 2003 INTERNATIONAL BUILDING CODE (IBC) and 2004
SUPPLEMENTS pertaining to fire resistance in wood framing 16 inch O.C.
SECTION 703: FIRE RESISTANCE RATINGS AND FIRE TESTS
703.3 Alternative method for determining fire resistance
The application of any of the alternative methods listed in this section shall be
based upon fire exposure and acceptance criteria specified in ASTM E119. The required
fire resistance of a building element shall be permitted to be established by any of
the following methods or procedures;
- Fire-resistance designs documented in approved sources.
- Prescriptive designs of fire-resistance-rated building elements as prescribed in Section 720.
- Calculations in accordance with Section 721.
Advanced Fiber Technology uses "Section 721.6 Wood Assemblies" to calculate the fire
resistance when using our cellulose insulation in 1-hour rated assemblies. The criteria
for calculating the fire resistance is:
721.6.2.1 Fire-resistance rating of wood frame assemblies
The fire-resistance rating of a wood frame assembly is equal to the sum of the time
assigned to the membrane on the fire exposed side, the time assigned to the framing
members and the time assigned for additive contribution by other protective measures
such as insulation. The membrane on the unexposed side shall not be included in
determining the fire resistance of the assembly.
721.6.2.2 Time assigned to membranes
Table 721.6.2(1) indicates the time assigned to membranes on the fire-exposed side.
The following are select building materials from Table 721.6.2(1) and apply only to
framing members 16" O.C. If you want a copy of the complete table, please contact us.
Specific installation instructions for the wallboard are contained in the IBC.
Table 721.6.2(1): TIME ASSIGNED TO WALLBOARD MEMBRANES
| Description of Finish | Time (Minutes) |
| 1/2-inch gypsum wallboard | 15 |
| 5/8-inch gypsum wallboard | 30 |
| 1/2-inch Type X gypsum wallboard | 25 |
| 5/8-inch Type X gypsum wallboard | 40 |
| Double 1/2-inch gypsum wallboard | 40 |
Table 721.6.2(2):TIME ASSIGNED FOR CONTRIBUTION FOR WOOD FRAME
| Description of Finish | Time (Minutes) |
| Wood studs 16 inches O.C. | 20 |
| Wood floor & roof joists 16 inches O.C. | 10 |
- This table does not apply to studs or joists spaced more than 16 inches O.C.
- All studs shall be nominal 2x4 and all joists shall have a nominal thickness of at least 2 inches.
- Allowable spans for joists shall be determined in accordance with Sections 2308.8, 2308.10.2, and 2308.10.3.
Table 721.6.2(5) TIME ASSIGNED FOR ADDITIONAL PROTECTION
| Description of Finish | Time (Minutes) |
|
Add to the fire resistance rating of wood studs if the spaces between the studs
are completely filled with glass fiber mineral wool batts weighing not less than
2 pounds per cubic foot (0.6 pound per square foot of wall surface) or rockwool
or slag material wool batts weighing not less than 3.3 pounds per cubic foot
(1 pound per square foot of wall space), or cellulose insulation having a nominal
density of not less than 2.6 pounds per cubic foot.
| 15 |
As an example using the IBC calculation method and IBC time assigned values contained
in Table 721.6.2(1), Table 721.6.2(2), and Table 721.6.2(5), one could calculate the
fire resistance for the following wall configuration.
| Example 1: | |
| a) 1/2-inch Type X gypsum wallboard | 25 minutes - Table 721.6.2(1) |
| b) Wood Studs 16 inches O.C. | 20 minutes - Table 721.6.2(2) |
| Subtotal | 45 minutes |
| c.) Additional Protection - 2.6 pcf or greater installed cellulose insulation | 15 minutes - Table 721.6.2(5) |
| Total Fire Resistance | 60 minutes |
* From GA-600-2003 Fire Resistance Design Manual
Summary:
The International Building Code recognizes the fire resistance superiority of cellulose
insulation compared to standard light density fiberglass batts or foam insulation. An
additional 15 minutes of protection is provided by cellulose insulation while 0 minutes
are permitted for light density fiberglass batts and foam insulation.
Cellulose....it's naturally better insulation
The following pages contain all Cellulose Insulation fire related material.
R-TEK Insulation is your insulation contractor of choice.
If you have any questions regarding commercial or home insulation please do not hesitate
to call us at: (330) 753-8394. We will be more than happy to assist you.
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