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Fiberboard Sheathing Fire Ratings
Insulating Board Sheathing Fire Resistance
- POST a QUESTION or COMMENT about fiberboard building sheathing fire ratings for ptoducts such as Celotex, Homasote, Insulite & other brands
Fiberboard insulating sheathing fire ratings:
Fire resistance of fiberboard sheathing used on roofs, exterior walls, interior walls & ceilings.
This articleseries describes and provides photographs that aid in identifying various insulating board sheathing materials used on building walls and roofs, such as Homasote, Celotex, Insulite, and Masonite insulating board sheathing products.
We describe the components, properties, and applications of various fiberboard, hardboard, and insulating board or sound deadening board products. W
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Fire Ratings & Fire Resistance of Fiberboard Sheathing
9 September 2015 Andre said:
Is older homasote board a fire-rated wall covering? I'm doing some renovation in a mid-19th century house. One attic room was converted to a bedroom by putting homasote panels over the approximately 1x6 planks that covered the interior attic walls.
I don't know when this took place, but guess it was at least a couple decades ago, if not considerably longer.
Is homasote of that age fire-rated? Would the total assembly (homasote over 1x planks) be fire-rated? If not, can I get to a fire-rated assembly by applying 1/2" drywall directly over the homasote?
Reply: here will provide fiberboard fire rating tables & data
Andre:
While there are some modern fiberboard products that are fire rated you cannot safely assume that a new much less an antique fiberboard sheathing is fire-rated nor that it has good fire resistance.
In fact some,perhaps many fiberboard sheathing products were treated with a wax or other substances for water-resistance, increasing the combustability of the material. Fire experts cite building sheathing, including fiberboard, as an important fuel contributing to fire spread on buildings.
The exterior fire has layers of fuel that contribute to the fire: vinyl siding and trim, flammable insulation (foam or fiber board), and flammable sheathing (plywood or OSB). All contribute to a large body of fire outside the structure that is providing a flow path up to the eaves or soffits that provide little or no resistance to the vertical spread.
The exterior fire is fueled not only by the siding but also by the building insulation (foam or fiber board) that is directly under the siding (photo 8). Plastic house wrap may be under the insulation and, of course, the sheathing of oriented strand board (OSB) is under that.
The OSB contains large amounts of glue to hold the strands together to form a usable board. All of these combustible components contribute to creating a large body of exterior fire. - Fire Engineering, "Rapid Fire Spread at Private Dwelling Fires", (Vol. 166, October 2013), retrieved 14 September 2015, original source: http://www.fireengineering.com/articles/print/volume-166/issue-10/features/rapid-fire-spread-at-private-dwelling-fires.html
HIlado (1998) cites the flammability of fiberboard sheathing products and other sources such as some testing agency and U.S. state agencies cite the flame spread ratings as follows:
Flame Spread Classification of some Common Building Materials |
||
| Material or wood species | Flame Spread Rating | Flame-Spread Class |
| Hardboard siding panels | < 200 | III |
| PA Wood Structural Panels (includes APA 303 Sidings such as T1-11) | 76-200 | III |
| Brick | 0 | I |
| Cedar, Western Red | 69 | II |
| Fiberboard, Medium Density | 167 | III |
| Gypsum Wallboard | 10-15 | I |
| Fiber Cement exterior materials | 0 | I |
| Inorganic reinforced cement board (such as asbestos cement millboard) | 0 | I |
| Masonite | <200 | III |
| Particle Board | 116-178 | III |
| Plywood, pine | 120-140 | III |
| T-111 | 76-200 | III |
Notes to the table above
Source: Louisiana State Government, "Information on Construction Requirements, Flame-Spread Ratings", retrieved 14 Sept 2015, original source: http://sfm.dps.louisiana.gov/doc_flamespread.html
Hilado, Carlos J. Flammability handbook for plastics. CRC Press, 1998. Excerpting, this handbook notes in Table 3.2 Ignitability Characteristics of Some Materials as Measured by the USF Ignitiability Test [excerpts, p. 69]
- At a heat flux W/cm2 for three heat flux levels of 5.8, 8.1, and 10.5,
- Cellulose fiberboard, 1/2 -inch has an ignition time of 11 seconds, 5 seconds, and 3 seconds
- Fiberboard soundstop, 1/2-inch has an ignition time of 15 seconds, 6 seconds, and 4 seconds
- Fiberboard sheathing, 1/2-inch has an ignition time of 17 seconds, 7 seconds, and 5 seconds
- Medium density fiberboard, 1/2-inch has an ignition time of 34 seconds, 21 seconds, and 14 seconds
- Hardboard, 3/8 inch, has an ignition time of 77, 26, and 17 seconds respectively
- Hardboard, unfinished, 1/4-inch has an ignition time of 222 seconds, 22 seconds, and 12 seconds
- Cotton fabric has an ignition time of 10 seconds, 6 seconds, and 3 seconds
Flame-Spread Classification Flame-Spread Rating or Index for the three classes
Class I (or A) 0 - 25
Class II (or B) 26 - 75
Class III (or C) 76 - 200
From the first reference above:
The most widely accepted flame-spread classification system appears in the National Fire Protection Association Life Safety Code, NFPA No. 101. This Code groups the following classes in accordance with their flame-spread and smoke development:
Class A - Flame-spread 0-25, smoke developed 0-450.
Class B - Flame-spread 26-75, smoke developed 0-450.
Class C - Flame-spread 76-200, smoke developed 0-450.
NFPA 101 primarily applies this classification to interior wall and ceiling finish materials. Roof coverings must meet a different set of criteria.
Watch out: Unless you know that your fiberboard is a fire-rated product the safer assumption can be inferred from this note from Georgia Pacific about its "regular fiberboard sheathing”:
GP Sheathing products are marked with a hazard label because they may be a potential fire hazard if exposed to flame, such as plumbing torches. Caution must be taken that these products do not come in contact with open flame or with temperatures high enough to ignite them or cause smoldering combustion. Regular Fiberboard Sheathing products should not be used under stucco.
Homasote currently offers a medium density fiberboard boards designed for use in residential and commercial buildings that require a Class A (25 flame spread) rating. That does not by any means claim that all fiberboard sheathing of all brands and ages carries a Class A flame spread rating.
Early efforts to make fiberboard fire RESISTANT show up in patent disclosures and fiberboard sheathing product modern fire ratings are discussed by the various manufacturers of fiberbboard such as Georgia Pacific and Homasote.
- Becher, Hubert L. "Fire resistant pulp board." U.S. Patent 2,108,761, issued February 15, 1938
- Fire Engineering, "Rapid Fire Spread at Private Dwelling Fires", (Vol. 166, October 2013), retrieved 14 September 2015, original source: http://www.fireengineering.com/articles/print/volume-166/issue-10/features/rapid-fire-spread-at-private-dwelling-fires.html
- Georgia-Pacific Wood Products, "Regular Fiberboard Sheathing Installatin Instructions",Georgia-Pacific Building Products 133 Peachtree Street NE Atlanta, GA 30303 (404) 652-4000 (March 2014) - retrieved 14 Sept 2015, original source: available at http://www.buildgp.com/regular-fiberboard-sheathing
- Georgia-Pacific Wood Products, "Stedi-R® Structural Fiberboard Wall Sheathing", op.cit.,
- Hilado, Carlos J. Flammability handbook for plastics. CRC Press, 1998. Excerpting, this handbook notes in Table 3.2 Ignitability Characteristics of Some Materials as Measured by the USF Ignitiability Test [excerpts, p. 69]
- Leopold, Becher Hubert. "Fire-resistant product from comminuted woody material, urea, or melamine-formaldehyde, chlorinated hydrocarbon resin, and hydrated alumina." U.S. Patent 2,680,102, issued June 1, 1954. describes the treatments used on fiberboard sheathing to improve its fire resistance.
- Brenden, John J., and Erwin L. Schaffer. Smoldering Wave-Front Velocity in Fiberboard. No. FSRP-FPL-367. FOREST PRODUCTS LAB MADISON WI, 1980. Excerpting:
Fiberboard is used in large quantities for use in a broad spectrum of housing and building applications, one of which is sound-deadening board. As a result of reports documenting fire experiences with sound-deadening board, research was undertaken toward reducing or eliminating smoldering tendencies of fiberboard products.
This report reviews previous work and reports on a test method to reproducibly measure smoldering wave-front velocity.
...
Continue reading at PROTECT FIBERBOARD from WATER or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.
Or see these
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Citations & References
In addition to any citations in the article above, a full list is available on request.
- [1] Homasote® Company, 932 Lower Ferry Road, West Trenton, NJ 08628-0240 Tel: 800-257-9491 Ext 1332, or from outside the U.S. call 609-883-3300. Website: http://www.homasote.com/ , Email: Sales@homasote.com.
- Thanks to Homasote CEO Warren Flicker for technical review and comment on this article.
- Mark Cramer Inspection Services Mark Cramer, Tampa Florida, Mr. Cramer is a past president of ASHI, the American Society of Home Inspectors and is a Florida home inspector and home inspection educator. Mr. Cramer serves on the ASHI Home Inspection Standards. Contact Mark Cramer at: 727-595-4211 mark@BestTampaInspector.com
- John Cranor [Website: /www.house-whisperer.com ] is an ASHI member and a home inspector (The House Whisperer) is located in Glen Allen, VA 23060. He is also a contributor to InspectApedia.com in several technical areas such as plumbing and appliances (dryer vents). Contact Mr. Cranor at 804-873-8534 or by Email: johncranor@verizon.net
- [2] Celotex Corporation, PO Box 31602, Tampa FL 33631, with offices in Atlanta, Chicago, Cincinnati, Dallas, Oakland and Philadelphia, and plants in six U.S. States is headquartered in Tampa, FL. Celotex is a national manufacturer of residential and commercial building materials. Website: www.celotex.com Tel: 800-CELOTEX
"Insulation Selector Guide", Celotex Corporation, web search 6/29/12, original source: http://www.silvercote.com/PDF/ThermaxInsulSelectorGuide.pdf, [copy on file as CelotexThermaxInsulSelectorGuide.pdf ]
"Celotex Blue Ridge Fiberboard", SturdyBrace®, produced by Blue Ridge Fiberboard Inc., 250 Celotex Dr., Danville VA 24541, product literature, web search 6/29/2012, original source: blueridgefiberboard.com/pages/sturdybrace.php, [Copy on file as Celotex_BlueRidge_SturdyBrace.pdf].
MSDS: original source: blueridgefiberboard.com/pages/sturdybrace/pdfs/SturdyBrace-msds-br.pdf
"Guide Specifications: SturdyBrace® Structural Fiberboard Wall Sheathing", 6/29/12, original source: blueridgefiberboard.com/pages/sturdybrace.php [Copy on file as SturdyBrace-guidespecs.pdf] - [3] Douglas Leen, Petersburg AK 99833, contributed the photograph of insulating board scraps from roof insulation removed from a building. Dr. Leen provides such a wide range of services, collectables, and historical information about the Northwest that a succinct description is difficult: flying dentist goes anywhere, antique forestry posters, historic campers, the tugboat Katahdin, in Alaska, Washington, and Wyoming. Mr. Leen can be contacted at mail@dougleen.com or at 907-518-0335
- [4] Georgia Pacific: information about DensGlas gypsum board building sheathing can be found at the company's website at gp.com/build/product.aspx?pid=4674
- [5] "Roof Shingle Tear-Off Procedure for Homasote Products", PDF document, Homasote Co., 932 Lower Ferry Road, West Trenton, New Jersey 08628-024, U.S.A. 800-257-9491 website: at www.homasote.com
- [6] Thermafiber, Inc., (now a division of Owens Corning®) at Thermafiber, Inc., 3711 Mill Street, Wabash, IN 46992, Tel: 888-834-2371 (U.S. & Canada) - 260-563-2111 Website: www.thermafiber.com or Thermafiber technical services at 888-834-2371 (U.S. & Canada) ; Phone: 260-569-0801, Fax: 260-563-8979 or Email: technicalservice@owenscorning.com
- [7] Weaver: Beaver Board and Upson Board: Beaver Board and Upson Board: History and Conservation of Early Wallboard, Shelby Weaver, APT Bulletin, Vol. 28, No. 2/3 (1997), pp. 71-78, Association for Preservation Technology International (APT), available online at JSTOR.
- [8] Pittsburgh Press, "Yesterday - in costly homes alone, Today even the simplest home can have this hidden comfort", The Pittsburgh Press, 19 April 1925, classified ads section. Web search 6/22/12, [Copy on file as Celotex_Ad_023_PP.jpg and more]
- [9] pending research
- [10]
Patents pertaining to building insulation & insulating board, Celotex & Insulating Board type products
- "Sound absorbing board for walls and ceilings", Patent No. 1,554,180, issued to W.S. Trader, September 15,1925, first disclosed a wallboard constructed from "Celotex", a felted mass of strong bagasse fibers, so compacted as to be capable of use as an artificial lumber in that it can be sawed and nailed, and has sufficient strength in many cases to be substituted for lumber. That same patent mentions "Insulite", a building board made from wood pulp tailings and which likewise has a porous fibrous body portion and which is possessed of considerable strength so that the same can be nailed, etc. Celotex was preferred as an insulating material because its internal cells produce a sound-deadening insulating effect.
- "Method and apparatus for drying moving material", Treadway B. Munroe et als, assigned to Dahlberg & Co., U.S. Patent No. 1,598,980, 7 September 1926, described a method and apparatus for drying sheets of artificial heat insulating lumber, known on the market as Celotex, improving the original process.
- "Reenforced composition board", Treadway B. Munroe et als, U.S. Patent No. 1,578,344, 30 March 1926
- "Insulating Structural Board", U.S. Patent 2,159,300, Armen H. Tashjian et als, assigned to William B. Miller, Lakewood OH, 23 May 1939, describes insulating structural boards of laminated construction for use as roof or floor slabs, and refers to "Standard insulating fiber boards, such as "Celotex", "Masonite", "Insulite", etc. that had excellent insulating properties but have relatively slight structural strength in flexure or bending under load, hence are not and cannot be used as structural slabs for load sustaining purposes, as roof or floor slabs, for example. [Adding structural strength ran into the problem of reducing the insulating value of the product.]
- "Sound-absorbing chamber", Treadway B. Munroe et als, U.S. Patent No. 1,705,778, 19 March 1929 (using Celotex to construct a sound deadening chamber.
- "Method of and apparatus for drying moving material", U.S. Patent 2,376,612, Carl G. Muench, New Orleans, assigned to Celotex Corporation, described a method and apparatus for drying sheets of artificial heat insulating lumber, preferably formed by the felting of bagasse fiber along with other materials necessary to make a satisfactory structural fiber board. 22 May 1945
- "Sound-absorbing board for walls and ceilings," U.S. Patent 1,554,180, Sept. 15, 1925, Wilber S. Trader, assignor to Dahlberg & Company, Chicago IL. described an interior-use sound insulating product.
- [11] "Insulite Co. v. Reserve Supply Co.," 60F.2d 433 (1932), Circuit Court of Appeals, Eighth Circuit, July 26, 1932. Web Search t/23/12. Quoting:
Rabbeted joints in material to which plaster or other material is applied are found in the Jones patent, No. 886,813. In this patent the composition is made up of plaster of paris, cement, or other like substance, combined with hair, wood fiber, sawdust, wool, wood shavings, excelsior, straw, or similar substances. The length of the lath covers three joists instead of four. The boards are arranged in staggered relation to each other and the joints are shiplapped. The specification states that after the boards or blocks are placed in position they may be covered with wallpaper or other similar material, which, of course, would include plaster.- "Machine for perforating Insulite Boards", U.S. Patent No. 1,306,283, Patented 10 June 1919, John K. Shaw, inventor from Minneapolis MN, describes improvements for machines for perforating Insulite Boards.
- "Before you Build write for this mailing piece and a sample of Insulite", [advertisement], The Literary Digest, 13 September 1940.
- [13] "Separating the Fiber of Wood", A.S. Lyman, U.S. Patent No. 21,077, 3 August 1858
- [14] Standards pertaining to fiberboard insulating sheathing:
- ASTM C 208-95 (2001) – Standard Specification for Cellulosic Fiber Insulating Board. Type IV Grade 2 (Structural Wall Sheathing).
- ASTM C 846-94 (2003) – Application of Cellulosic Fiber Insulating Board for Wall Sheathing.
- ASTM D 1554 - Definitions of terms Relating to Wood Based Fiber and Particle Panel Materials.
- ASTM E-72 (1997)- Standard Method for Conducting Strength Tests of Panels for Building Construction.
- ANSI /AHA - A194.1, Cellulosic Fiberboard.
- U.S. Department of Commerce: PS57-73, Cellulosic Fiber Insulating Board
- A.F.A. (2003): Fiberboard Sheathing test results
- [15] "Properties of insulating fiberboard sheathing", Forest Products Laboratory (U.S.) Luxford, R. F. (Ronald Floyd), 1889 (1960), original report 1955, citation:hdl.handle.net/1957/2489, web search 6/29/12, original source: http://ir.library.oregonstate.edu/xmlui/handle/1957/2489
- BASEMENT MOISTURE CONTROL [PDF] U.S. Department of Energy
- Building Failures, Diagnosis & Avoidance, 2d Ed., W.H. Ransom, E.& F. Spon, New York, 1987 ISBN 0-419-14270-3
- Building Pathology, Deterioration, Diagnostics, and Intervention, Samuel Y. Harris, P.E., AIA, Esq., ISBN 0-471-33172-4, John Wiley & Sons, 2001 [General building science-DF] ISBN-10: 0471331724 ISBN-13: 978-0471331728
- Building Pathology: Principles and Practice, David Watt, Wiley-Blackwell; 2 edition (March 7, 2008) ISBN-10: 1405161035 ISBN-13: 978-1405161039
- Design of Wood Structures - ASD, Donald E. Breyer, Kenneth Fridley, Kelly Cobeen, David Pollock, McGraw Hill, 2003, ISBN-10: 0071379320, ISBN-13: 978-0071379328
This book is an update of a long-established text dating from at least 1988 (DJF); Quoting:
This book is gives a good grasp of seismic design for wood structures. Many of the examples especially near the end are good practice for the California PE Special Seismic Exam design questions. It gives a good grasp of how seismic forces move through a building and how to calculate those forces at various locations. THE CLASSIC TEXT ON WOOD DESIGN UPDATED TO INCLUDE THE LATEST CODES AND DATA. Reflects the most recent provisions of the 2003 International Building Code and 2001 National Design Specification for Wood Construction. Continuing the sterling standard set by earlier editions, this indispensable reference clearly explains the best wood design techniques for the safe handling of gravity and lateral loads. Carefully revised and updated to include the new 2003 International Building Code, ASCE 7-02 Minimum Design Loads for Buildings and Other Structures, the 2001 National Design Specification for Wood Construction, and the most recent Allowable Stress Design. - Diagnosing & Repairing House Structure Problems, Edgar O. Seaquist, McGraw Hill, 1980 ISBN 0-07-056013-7 (obsolete, incomplete, missing most diagnosis steps, but very good reading; out of print but used copies are available at Amazon.com, and reprints are available from some inspection tool suppliers). Ed Seaquist was among the first speakers invited to a series of educational conferences organized by D Friedman for ASHI, the American Society of Home Inspectors, where the topic of inspecting the in-service condition of building structures was first addressed.
- Domestic Building Surveys, Andrew R. Williams, Kindle book, Amazon.com
- Defects and Deterioration in Buildings: A Practical Guide to the Science and Technology of Material Failure, Barry Richardson, Spon Press; 2d Ed (2001), ISBN-10: 041925210X, ISBN-13: 978-0419252108. Quoting:
A professional reference designed to assist surveyors, engineers, architects and contractors in diagnosing existing problems and avoiding them in new buildings. Fully revised and updated, this edition, in new clearer format, covers developments in building defects, and problems such as sick building syndrome. Well liked for its mixture of theory and practice the new edition will complement Hinks and Cook's student textbook on defects at the practitioner level. - Historic Preservation Technology: A Primer, Robert A. Young, Wiley (March 21, 2008) ISBN-10: 0471788368 ISBN-13: 978-0471788362
- VAPOR BARRIERS or VAPOR DIFFUSION RETARDERS [PDF] U.S. DOE - how vapor barriers work, types of vapor diffusion barriers, installing vapor barrier
- In addition to citations & references found in this article, see the research citations given at the end of the related articles found at our suggested
CONTINUE READING or RECOMMENDED ARTICLES.
- Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. Tel: (416) 964-9415 1-800-268-7070 Email: info@carsondunlop.com. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.
Thanks to Alan Carson and Bob Dunlop, for permission for InspectAPedia to use text excerpts from The HOME REFERENCE BOOK - the Encyclopedia of Homes and to use illustrations from The ILLUSTRATED HOME .
Carson Dunlop Associates provides extensive home inspection education and report writing material. In gratitude we provide links to tsome Carson Dunlop Associates products and services.
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