International Code Adoptions
· The International
Building Code is
adopted at state or local levels in all 50 states plus Wash., D.C.
· The International
Fire Code is
adopted at the state
or local level in 41 states plus
Washington, D.C.
Updated: 02/08/08
IBC
803.4.2 Where
walls and ceiling are required to be of fire-resistive or noncombustible construction
and walls are set out or ceilings are dropped distances greater than
specified in
Section
803.4.1*, Class A finish materials shall be used except where interior finish materials
are protected on both sides by an automatic sprinkler system or attached to
noncombustible backing or furring strips . . .hangers and assembly members. *803.4.1 stipulates 1 3/4”
NFPA
13-8.14.1.1 All concealed spaces enclosed wholly or partly by exposed combustible
construction shall be protected by sprinklers. . .. Exception 8.14.1.2.10: Concealed spaces where rigid
material are used and the exposed surfaces have a flame spread rating of 25
or less and the materials have been demonstrated not to propagate fire in the
form in which they are installed shall not require sprinkler protection.
Fig 1) ICC Table 803.5. Red
Highlights indicate typical Occupancy Groups specifying suspended wood
ceiling designs.
Fig 2) Steiner Tunnel
Fig 3) Typical Flame Spread Index
required for specific
areas (see Codes Section 8 Interiors for full details and Group Occupancy per
Table 803.5)
Fig 4) Flame Spread Indexes of
wood
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Springfield, OR 97477
Tel 888.767.9990
Fax 888.767.9998
www.9wood.com
FIRE RATING
The following information is intended as a general overview of Fire Rating for suspended wood ceilings. The final authoritative voice on this subject should be the codes that apply to your project, community, and product data sheets. The fire retardant products utilized by 9Wood are reviewed briefly.
1.0 CURRENT CODE
The International Code Council (ICC) was established in 1994 as a nonprofit organization dedicated to developing a single set of comprehensive and coordinated national model construction codes. The founders of the ICC are Building Officials and Code Administrators International, Inc. (BOCA), International Conference of Building Officials (ICBO), and Southern Building Code Congress International, Inc. (SBCCI). Since the early part of the last century, these nonprofit organizations developed the three separate sets of model codes used throughout the United States. When the time came for a single set of codes, the nation’s three model code groups responded by creating the International Code Council and by developing codes without regional limitations.
The most critical sections of the new IBC (Int’l Building Code) relating to fire ratings are: · Use or Occupancy Classification · Special Use or Occupancy Requirements · Types of Construction · Fire Resistant Materials and Construction · Interior Finishes · Fire Protection Systems · Means of Egress · Accessibility
The most significant of these
include IBC & IFC Section 8: Interiors, IBC Section 4: Special
Occupancies, and NFPA 13: Sprinklers---Concealed Spaces. IMC Section 6: Ducts and Plenums apply
for Return Air Plenums. The building occupancy group as well as local codes
and fire marshal interpretations of those codes give final consideration.
1.1 CODE SECTIONS TO CONSIDER
Three code sections have the greatest control over wood
ceiling fire codes:
· IBC
803.5 [Interiors]
Interior finish requirements based on Building Group (Flame Spreads
permitted)
· IBC
803.4.2 [Interiors] Set-out construction (suspended dropped ceilings)
· NFPA
13 [Sprinklers]
8.14.1 Concealed Spaces
Significantly,
concern for the concealed space above the ceiling drives fire
retardant code requirements. In Concealed Spaces (NFPA’s term) or Dropped
Ceilings (IBC’s term), code and standard both demand treatment in one of
three ways:
· Sprinklers,
· Class
I materials on all surfaces, or
· In-fill
with Class I material.
Ceilings in spaces
where people work such as corridors and meeting rooms are rated Class
III—mitigated sometimes by the non-use of sprinklers, the egress zone and the
Occupancy Group.
þ Point to Remember: The space above the wood ceiling requires fire retardant treatment. Any suspended ceiling
material that interfaces with the Concealed Space must address the code. If
the Concealed Space is sprinklered, you don’t need a Class I wood ceiling. If
there are not sprinklers, you do.
2.0 FIRE
Approximately 75% of all codes deal with Fire and Life Safety. These are critical design issues affecting virtually every aspect of building construction. The code’s first priority is prevention, then rapid detection and suppression, and finally evacuation.
Fire Codes involve both fire protection and smoke protection which are addressed in the codes in several overlapping ways. · Building Types · Building Materials [suspended wood ceilings fall here] · Building Systems
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2.1 FIRE
RATED VS FIRE RETARDANT
A clear distinction should be made between fire barrier assemblies which utilize Fire Resistant materials (Rated) and Fire Retardant materials (Indexed). The terms sound alike--and are often confused--but are quite distinct. Rated materials prevent ignition over a fixed length of time. Fire Retardant materials, on the other hand, will ignite. They slow down, however, the flame spread and smoke development of the burning material. A low flame spread material will not necessarily improve the performance of a fire rated assembly. Fire Retardant materials are commonly used by the codes for interior finish materials. Suspended wood ceilings typically fall under the jurisdiction of Section 8 Interiors.
þ Point to Remember: Flame spread and smoke
development values relate to the surface burning characteristics of a
product. Hourly fire resistant ratings relate to the ability of a building
assembly to contain a fire--such as a 1 hour wall assembly. There is a
significant difference between them.
3.0 FIRE RETARDANCY
3.1 Flame Spread: The Flame Spread Index is an arbitrary scale. The Flame Spread Index (now called the Surface Burning Characteristics Rating) fixed Concrete-board at 0 and Red Oak at 100. Note that this is a scale not a rate at which flame actually spreads along material’s surface.
It works like this: 3.1.1 Steiner Tunnel Test: The test used to calibrate a material’s Flame Spread Index is called the "Method of Test of Surface Burning Characteristics of Building Materials" (NFPA No. 255, ASTM E 84, UL No. 723). It is commonly known as the Tunnel Test. A 2’ x 20’ sample of the material to be tested is placed along the inside top of a long metal horizontal furnace. Two ¾” open gas flames are applied at one end and a 3 mph regulated constant draft is directed through the tunnel from the flame end. The progress of the flame front along the sample is observed through side windows and timed to fix the Flame Spread Index (FSI). Smoke is also collected to fix the Smoke Developed Index (SDI).
Al Steiner, a UL engineer, developed the method in 1948 to create a repeatable, consistent test method (see www.ul.com). 9Wood uses several testing labs for our tunnel tests.
3.2 Smoke Developed Index:
A Smoke Developed Index is also measured for various
materials. The Smoke Developed Index fixes 100 as the smoke development of
Red Oak.
4.0 APPLYING FIRE RETARDANANCY TO SUSPENDED WOOD
CEILINGS
4.1 Wood’s Natural Retardancy
Wood typically provides, in its natural, raw state, a Class III rating (see Fig 4). However, some dense tropical Ironwoods, such as Ipe, provide a Class I naturally. Other species, such as true firs, receive a Class II naturally. Still, for the vast majority of species, an additive must be employed to improve the Flame Spread Index. þ Point to
Remember: For most purposes, the majority
of wood finishes, veneers or lumber, require some type of treatment to
achieve a Class I Rating.
4.2 Obtaining a CLASS I
Several chemical processes exist to slow the flame spread and smoke developed to comply with a Class I fire rating.
4.2.1 Fire Rating Cores (for
Veneered Products)
Section 8
Interiors in the Codes stipulates that if the veneer is less than 1/28” thick
(having surface burning characteristics no greater than paper), then the
substrate confers the Fire Retardant classification. This means that if you use Class I
substrates with standard veneers, the entire assembly receives a Class
I. 9Wood utilizes Duraflake FR
particleboard, fabricated in Albany, Oregon by Flakeboard. Several advantages of veneers on FR
cores exist, including grain and color consistency, tolerance control, and
often cost efficiencies. Disadvantages are length structure limitations and
difficulty of field cutting because of exposed cores.
þ Point to Remember: If the core is Class I, the assembly
will be Class I
4.2.2 Fire Retardant Coatings (for
Solid Wood)
Several
commercial fire retardant clear coatings exist. Most discolor the final finish, or create a “plastic”
looking finish. 9Wood uses a
clear intumescent penetrant specially developed for 9Wood and our wood
ceiling products. It seals and provides a clear top coat finish along with
staining capabilities.
þ Point to Remember: Solid wood requires (almost always) a
topical coating treatment to achieve a Class I rating.
4.2.3 Fire Rating Impregnations
Several
commercial products exist that impregnate wood or engineered wood products to
deliver a Class I. These require a UL certified, pressurized tank process,
and secondary kiln drying. Wood
products emerging from this process can be discolored and warped.
þ Point to Remember: Pressure impregnation is not
recommended for architectural wood. 9Wood has been conducting experiments
using fire rated exterior plywood with a subsequent architectural veneer
lamination.
5.0 CURRENT
ISSUES IN SUSPENDED WOOD CEILINGS AND FIRE RETARDANCY
5.1 Exteriors
Most exterior soffits do not require Class I Flame Spread Index. Check with local code
requirements. Note: California’s
new exterior fire codes.
5.2 LEED,
FSC, NAUF & Fire Retardant cores
Currently, no FSC cores (particleboard) are made with fire retardant
compounds. Recently a new FR particleboard with No Added Urea Formaldehyde
(NAUF) has been test marketed . CARB (California Air Resources Board) and
LEED (Leadership in Environmental and Energy Design) are championing many
changes to the fabrication of commercial cores. Dilemas still remain, such as
only Class III FSC (MR-7) cores, but the products available in this category
are evolving constantly. Check with 9Wood for latest FR core products.
þ Point to Remember: Stay in touch with 9Wood for up-dates
regarding Green/Engineered wood.
5.3 Pyroblock® Pyroblock®
is a propriatary fire retardant process developed by PanelSource
International to solve some of the limitations mentioned above. 9Wood is
proud to be a partner with this innovative company. The Pyroblock® process
unique intumescent coating for use on wood products. This coating results in
a fire retardant panel that achieves a Class I FR Rating. Pyroblock® panels
can be painted, laminated, or veneered. On certain 9Wood products, Pyroblock®
offers the possibilities of both an FSC core combined with a Formaldehyde
free core— and at the same time offering a Class I fire rating.
þ Point to Remember: Contact 9Wood for how to spec these
core products.
6.0 RESOURCES
9Wood: Charley Coury at ccoury@9wood.com
UL: www.ul.com
NFPA: www.nfpa.org
American Wood Council www.awc.org
California Air Resource Board: www.arb.ca.gov
International Code Council: www.iccsafe.org
Pyroblock: www.pyroblock.com
FlakeBoard: www.flakeboard.com
Sierra-Pine: www.sierrapine.com
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