| Testing Masonite Shingles |
| by
Stanley C. Stoll, M.Eng., E.I. |
| The term “masonite” shingle is a generic term referring to simulated wood shake shingles. Masonite shingles are made by compressing wood fibers, phenolic resin (glue) and wax (water repellant) into a shape that is intended to resemble wood shakes. Masonite shingles were popular in the mid-1980s through the mid-1990s as they had a moderate resistance to fire and claimed greater durability in resisting hail and wind damage. Due to poor performance and several lawsuits, all masonite shingles manufacturers stopped production around year 2000. Known product defects are premature degradation, cracking, curling and eventually disintegration. Since masonite shingles are no longer manufactured, and can no longer be repaired in some building department jurisdictions, they have become a target for fraud. The most common forms of fraudulent damage to masonite shingles are simulated hail and wind damage.
To help our clients distinguish between actual and fraudulent hail damage, Knott Laboratory has conducted research by launching simulated hailstones into a mock roofing system clad with aged masonite shingles. The only known published hail research regarding masonite shingles was performed on new shingles prior to the knowledge of the defects. Knott Laboratory used aged and defective masonite shingles for testing.
The hail impact testing was performed in our laboratory using a compressed air hail launcher that is currently capable of firing 3/4”, 1” and 1-1/4” diameter hailstones at speeds equivalent to those of naturally falling hailstones. Ice balls were used as simulated hailstones, and are considered to be a worst-case-scenario due to their greater density and hardness when compared to naturally formed hailstones. The mock hailstones are launched through a digital chronograph to insure the speeds are comparable to those of naturally falling hail. |
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| Based upon our hail research, we determined that 3/4” diameter hailstones are not capable of damaging the body of masonite shingles. However, the lower left hand corner of the shingle, which is typically thinner and more susceptible to damage from impact, can be fractured by a 3/4” diameter hailstone. By closely observing and documenting the character of the fracture, we are able to establish whether the damage was caused by hail or other means.
Knott Laboratory also conducted research to determine how wind uplift forces can effect masonite shingles. We have determined that masonite shingles can be damaged by wind uplift forces through one of two failure modes. The first wind failure mode is caused by a large gust, or series of gusts, of winds that remove or damage multiple shingles simultaneously. The second wind induced failure mode is caused by a fatigue failure of the fasteners wherein the fasteners fail from repeated uplift due to smaller more frequent wind gusts.
To better understand the magnitude of the uplift force required to remove a masonite shingle from a roof, through either of the aforementioned failure modes, we removed several shingles from a local residential roof and measured the forces required to remove the shingles. We then calculated the uplift forces generated by various wind speeds and compared them to the measured resistance of the shingle fastening system. Based on this comparison, we were able to determine that masonite shingles are not easily damaged by wind uplift forces. We were also able to identify several key factors which can be used to determine exactly how a shingle was removed or damaged.
Knott Laboratory will continue to perform wind related research on various roofing materials and continue to perform research on masonite shingles using the larger 1” and 1-1/4” mock hailstones as well as any other roofing products where weather related damages are unknown. Please
contact us for more information about our ongoing roofing research and how our expertise can assist you in recognizing fraudulent claims. Knott Laboratory also offers approved continuing education courses on a variety of topics, including roofing, at our facility or yours. |
| Company News |
| Regis A. David, Ph.D. joins the Mechanical Engineering Department at Knott Laboratory, LLC. Dr. David received his B.S., M.S. and Ph.D. degrees in Mechanical Engineering from Brigham Young University, Provo, UT.
Dr. David received his M.S. degree for his thesis entitled “Generalized Two-Dimensional Model to Reconstruct the Impact Phase in Automobile Collisions.” Dr. David worked for Altair Engineering as an Application Engineer in Everett, Washington. His responsibilities included teaching Altair’s software training classes to Boeing Employees and providing Finite Element Analysis consultant expertise to Boeing. Dr. David has also performed research and published papers in the area of MEMS (Micro-Electro-Mechanical Systems), specifically simulation and testing of micro molecule motion during nanoinjection. |
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| Ben T. Railsback, M.S., P.E. presents “Forensic Engineering 101 – Bringing the CSI Effect to Your Case” to the Spring Conference of the Young Lawyers Division of the American Bar Association on May 14th, 2011 in Las Vegas, NV.
For registration and more information, please visit the Young Lawyers Division of the American Bar Association website. |
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| Stanley C. Stoll, M.Eng., E.I. teaches a course on “Masonite Shingles” at the Wyoming Claims Association Annual Meeting in Cheyenne, Wyoming on Friday, May 20th, 2011. |
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| Richard M. Ziernicki, Ph.D., P.E. speaks to Missouri Association of Trial Attorneys 53rd Annual Convention on “Ethics and the Expert Witness” on June 26th, 2011 in Lake Ozark, MO.
For registration and more information, please visit the Missouri Association of Trial Attorneys website. |
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| Richard M. Ziernicki, Ph.D., P.E. presents “Advanced Techniques in Forensic Engineering & Animation” at the National Academy of Forensic Engineers (NAFE) Annual Meeting on July 14-17, 2011 in Las Vegas, NV.
For more information, please visit the NAFE website. |
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| Richard M. Ziernicki, Ph.D., P.E. speaks to Colorado Springs chapter of the Colorado Trial Lawyers Association on “Ethics and the Expert Witness” on July 27th, 2011 in Colorado Springs, CO. |
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| Richard M. Ziernicki, Ph.D., P.E. presents “Effective Use of the Latest Technology in Reconstructing Trucking Accidents” at the National Interstate Trucking Summit sponsored by the Association of Plaintiff Interstate Trucking Lawyers of America (APITLA) and The National Trial Lawyers on September 15-17, 2011 in St. Louis, MO. |
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| Knott Laboratory now has a YouTube channel where you can see our latest animations. |
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