AN UPDATE TO THE ENHANCED FUJITA SCALE

by Tim Marshall, P.E., Principal Engineer Emertitus, Meteorologist

Dr. Ted (Tetsuya) Fujita created a tornado damage scale in 1970 after the Lubbock, Texas tornado.  The damage scale was divided into six categories where F0 corresponded with minor damage to houses with estimated winds of 40 – 72 mph (18 – 32 m/s) all the way up to F5 where strong frame houses were swept off their foundations in estimated winds of 261 – 318 mph (117 – 142 m/s).  Dr. Fujita determined the failure wind speeds based on dividing the gap between the Beaufort Scale (which mariners use) and the Mach Scale (which aviators use) into 12 non-linear increments.

In the early 2000’s, wind engineering studies showed mounting evidence that wood-framed houses can be completely destroyed at wind speeds less than 261 mph (117 m/s).  Therefore, in 2001, the Wind Science and Engineering Center at Texas Tech University assembled a team of atmospheric scientists and wind engineers and developed the Enhanced Fujita (EF) Scale to address the inconsistencies of the F-Scale.  I was selected along with five other scientists to estimate failure wind speeds to various building types.

In 2007, the National Weather Service (NWS) adopted the EF Scale and began utilizing the recently published EF Scale document to evaluate building damage.  A copy of the EF Scale document can be found online at: https://www.spc.noaa.gov/faq/tornado/ef-ttu.pdf.  This document includes degrees of damage (DODs) to 28 Damage Indicators (DIs) and was much more complex and accurate than the original F Scale.  However, concerns remained about the relationships between the observed DoDs and wind speed ranges. Some DIs had limited guidance available.   Users of the original EF Scale asked for new DIs to be created, especially in rural areas where building DIs are not common. More recently, alternative methods of estimating wind speeds have been published, including mobile Doppler radar measurements, tree-fall pattern analysis, and failure analysis of engineered structures. None of these methods had been included in the process of estimating tornado wind speeds. As a result, there have been awkward adjustments in tornado intensity by the NWS, including El Reno, OK and Bennington, KS in 2013. Additionally, recent research comparing wind speeds estimated from mobile Doppler radar measurements to speeds estimated from damage using the original EF Scale demonstrated an alarming trend, whereby wind speeds in approximately 40% of tornadoes were underestimated by two EF numbers. This means wind speeds for many tornadoes may be on the order of 50 mph greater than is currently being estimated and recorded in the national tornado database using the 2006 EF Scale (which is the dataset that serves as the basis for all tornado hazard maps).

In 2014, the American Society of Civil Engineers (ASCE)/Structural Engineering Institute (SEI) and the American Meteorological Society (AMS) undertook an effort to develop a consensus standard for tornado wind speed estimation. The forthcoming ASCE/SEI/AMS standard, Wind Speed Estimation in Tornadoes, will officially standardize the EF Scale. The committee undertaking this effort is organized into seven subcommittees, which were established to upgrade the EF Scale and develop methodologies to use treefall patterns, radar measurements, in-situ measurements, remote-sensing data and forensic engineering to estimate wind speeds. Requirements for archival of data will also be included in the standard.  Both myself and Dr. Christine Alfano, P.E./CCM with Haag serve on this committee.

Updates to Version 2 of the EF Scale include developing new DIs, such as center pivot irrigation systems, religious buildings, passenger vehicles, and wind turbines, as well as redefining existing ones using knowledge gained from more than two additional decades of conducting damage evaluations using the original EF Scale. Additional updates included combining single- and double-wide manufactured homes into a single DI, creating separate DIs for wood-frame and concrete residences, recategorizing schools as single- or multi-story, and revamping the hardwood and softwood tree DIs to focus on single or multiple trees instead. Wind resistance levels have also been defined to aid in estimating the wind speed associated with specific visible damage. Where new research exists from laboratory, modeling, or other sources of data, wind speeds for specific damage states are also being updated. Updates also include improvements and standardization of the DoDs and associated wind speeds across DIs, and standardization of a procedure for the use of the EF Scale method. Representative damage photographs to serve as guidance, as well as a commentary with references, have been added to each DI. Many of these damage photographs comes from damage surveys that I conducted.  However, the range of wind speeds that fall within each EF Scale category are not anticipated to change.

More than 80 scientists from various disciplines have volunteered their time to develop this standard. Thousands of hours have been put into this effort, and it is anticipated the standard will be published within the decade. Public input will be requested once the draft standard has completed the committee balloting process.  It is anticipated the new standard will be issued within the next few years.  Stay tuned to this blog for future updates.

By Tim Marshall, P.E., Meteorologist, Haag Principal Engineer

Tim Marshall is a structural engineer and meteorologist.  He has served as a Haag Engineer since 1983, assessing damage to thousands of structures (particularly damage caused by wind and other weather phenomena). He has written numerous articles, presented countless lectures, and appeared on dozens of television programs in order to share his extensive knowledge re: storms and the resultant damage.  He is a primary author of many Haag Education materials, including the Haag Certified Inspector-Wind Damage course. Mr. Marshall a pioneering storm chaser and was editor of Storm Track magazine. See his profile here.

Any opinions expressed herein are those of the author(s) and do not necessarily reflect those of Haag Global, Inc., Haag Canada, or any Haag companies. 

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Any opinions expressed herein are those of the author(s) and do not necessarily reflect those of Haag Engineering Co., Haag Construction Consulting, Haag Education, or parent company, Haag Global, Inc.

HAIL DENTED MY ROOF INSUALTION – NOW WHAT?

Large hail falls onto a commercial building covered with a single-ply TPO roof membrane. A roof inspector scours the whole roof front to back and left to right and does not find any hail-caused ruptures, but then notices the insulation is dented…Now what?

Single-ply roofing membranes can be fractured or torn when impacted by hailstones; however, many single-ply systems can resist being damaged by hail (including large hailstones) when the roofing membranes are relatively new and in good condition. Most single-ply systems are installed directly over insulation boards and a hailstorm that doesn’t damage the membrane can still cause dents in the underlying insulation. Concerns often arise about the thermal performance of insulation after being dented by hail.

The thermal performance of insulation is typically quantified by its R-value, which is a measure of heat flow resistance. Heat flow is thermal energy passing through a space due to a difference in temperatures. For example, if a roof is hot on a sunny summer day and the space inside the building is air conditioned, there will be some amount of heat energy flowing into the building through the roof.  Insulation on the roof reduces the rate of heat flow between the roofing and the roof decking, which reduces the heat flow into and/or out of the building.

Insulation R-value can be measured in a laboratory by using a heat flow meter (HFM). In order to determine if the R-value of insulation has been affected by hail-caused dents, samples of insulation can be removed from the roof and the R-value of dented and non-dented insulation can be measured and compared. Haag Research & Testing Co. (HRT) is currently studying the effects hail-caused dents have on the R-value of various types of roofing insulation and has performed R-value testing on numerous samples sent to the HRT laboratory.

HRT is accredited by International Accreditation Service (IAS) to perform ASTM C518 – Standard Test Method for Steady-State Thermal Transmission Properties by Means of the Heat Flow Meter Apparatus, and this test standard is followed by HRT when analyzing the thermal performance of roofing insulation.

Hail-dented insulation can be easily found in non-sheltered portions of the roof provided the hail was large enough and hard enough to cause detectible dents.  Non-dented insulation can be difficult to find after a substantial hailstorm; however, some roofs have tall equipment or taller portions of the building that can shelter a region of the roof from wind-driven hail, which can be useful in finding a sample of non-dented insulation. In the event non-dented insulation cannot be obtained, the R-value of dented insulation can be measured, then a comparable dent can be added to the insulation and the R-value re-measured to reasonably determine if hail-caused dents had a measurable effect on the insulation R-value.

Tests performed on roofing insulation often show little or no measurable change on the insulation R-value due to hail-caused dents; however, if  dents are sufficiently large, deep, or numerous, a subtle change in R-value can be measured. Also, very large hail can crack or rupture insulation, resulting in a thermal short through the insulation which can have a greater influence on the measured R-value. If concerns arise regarding the effects hail-caused dents had on the R-value of a roof, consider taking samples of the insulation for testing.

*More information on R-Value testing by Haag Research & Testing or contact us.

Steve R. Smith, P.E., is Director of Research & Testing and a Principal Engineer with Haag Global. He completed nuclear power training with the United States Navy in 1994. He was honorably discharged in 1998 and went to work for Haag Engineering Co. as Senior Laboratory Technician. Steve has performed hundreds of hail impact tests on a variety of products including roofing, siding, and automobiles.  He graduated from the University of Texas at Arlington in 2005 with a Bachelor’s degree in Mechanical Engineering and is a member of the American Society of Mechanical Engineers, the Society of Automotive Engineers, and the National Association of Fire Investigators. Steve has inspected and assessed damage to a number of roof systems, including single-ply systems, composition shingles, cedar shake and shingles, concrete tiles, slates, and built-up roofing. As Director of Research & Testing, Mr. Smith oversees all testing projects, protocols, and manages Haag’s accreditation. Mr. Smith is based at Haag headquarters in Flower Mound, Texas.

Any opinions expressed herein are those of the author(s) and do not necessarily reflect those of Haag Engineering Co., Haag Construction Consulting, Haag Education, or parent company, Haag Global, Inc.

Haag Fire O&C is dedicated to providing the highest-quality forensic investigations of fires and explosions in the industry. Our team of seasoned and court-tested investigators is committed to quickly finding the answers you need through industry-recognized scientific methods. With a thorough understanding of subrogation, liability, and fraud, Haag Fire O&C makes your job easier by answering all of your questions for O & C investigation and providing technical reports, if requested, within 5 business days for most non-legal residential and auto assignments. The team is led by Director of Fire Investigation Services, Edward Roberts, IAAI-CFI– a seasoned fire investigator with over 1,500 fire investigations and 25 years of experience investigating fires.

Haag Fire e-Minute:

CLASSIFYING FIRES

Why do we conduct fire investigations and why is it important to correctly classify the type of fire?

Edward G. Roberts, Director of Haag Fire O&C, breaks down the types of fires, why it makes a difference, and who should make that determination.

*More information on Haag Fire O&C and our team of seasoned fire investigators. 

*More information on Haag’s Certified Review Program.

Edward G. Roberts, IAAI-CFI, Director of Fire Investigation Services

As Director of Haag Fire O&C, I combine my lifelong experience and training in fire investigations with the training I received as an adjuster to create an approach to fire investigation and report product that best serves your needs through quick response time, clarity, and ease of use. As a member of a number of professional organizations, I am actively and constantly working to improve the industry of fire investigation.

• IAAI-CFI, CFEI, CVFI, CFII
• 1500+ fire and explosion origin and cause investigations
• Court-proven and reliable, including mediation, arbitration, and depositions
• Published internationally
• Obtain recorded statements
• Provide educational programs to insurance and investigation communities

Any opinions expressed herein are those of the author(s) and do not necessarily reflect those of Haag Engineering Co., Haag Construction Consulting, Haag Education, or parent company, Haag Global, Inc.

Dehumidification Basics

By Thomas Culver, CPAU, IICRC- MRS, WRT, FSRT

As a Senior Consultant for Haag Construction Consulting, I often find myself reviewing a mitigation estimate that has been included in a file to try to gain a better understanding of what the repair scope should look like. Many of these estimates appear to include an excessive amount of dehumidification equipment based on IICRC recommendations. While there may be loss specific circumstances that support an increase in the amount of equipment required, as a field inspector or desk reviewer, do you have a good understanding of the basic principles that help to determine the amount of dehumidification equipment necessary?

The first variable to consider is the total volume of the room or area in need of drying. This can be as simple as calculating the volume of one room or may involve several rooms. The room(s) may have flat ceilings, or sloped ceilings, in which case you may need to determine the average ceiling height. As a reminder, volume is measured in cubic feet (CF), and the basic formula to determine the total volume of a room is length*width*height (L*W*H). For irregular shaped rooms, you may need to first calculate the total area in square feet (SF), then multiply that by the ceiling height.

The second variable to determine is the class of water loss, which is based on the percentage of the total porous materials that are wet as a result of the loss. For example, a 12’ x 12’ room with 8-foot ceilings would have the following area available, assuming all finish materials are porous:

• 144 SF ceiling.
• 4 walls of 96 SF each.
• 144 SF floor.
  • Total of 672 square feet.

If the floors were completely saturated and all four walls were wet two feet up, there would be 240 SF of affected material. When divided by the total of 672 SF, that would result in approximately 35.7% of the total available area affected. The IICRC has defined the classes of water loss as follows:

• Class 1: Less than 5% of the available area is affected.
• Class 2: Between 5% and 40% of the available area is affected.
• Class 3: More than 40% of the available area is affected.
• Class 4: Complex assemblies, low evaporation materials. Also referred to as specialty drying.

Each class of water loss has been assigned a class factor that will help to determine how many AHAM pints per day are required for effective dehumidification. The AHAM rating is an efficiency rating applied by the Association of Home Appliance Manufacturers, where equipment is tested in a controlled environment of 80 F and 60% relative humidity. The following chart shows the class factor (X) to be applied based on the determination of the class of water loss.

The formula for determining total required AHAM pints is on the bottom of the class factor chart. Once we have determined the total CF of the drying chamber and the class factor of the loss, we can calculate the total AHAM pints necessary for proper dehumidification of the drying chamber.

If we have a drying chamber of 496 SF with 9-foot ceilings, we will first need to determine the volume of the chamber. 496*9 = 4,464 CF.

If the loss has been classified as a class 2 water loss, we can determine the total AHAM pints needed using the formula above. 4,464/50 = 89.28 AHAM Pints.

Most commercial dehumidifiers publish their efficiency rating in AHAM pints and estimating platforms classify dehumidifier size based on a range of AHAM rating. For example, Xactimate classifies a large dehumidifier as being AHAM certified for 70-109 pints per day. The dehumidifier necessary for the example above would be a large dehumidifier based on AHAM pints.

There is also a consideration needed for total air exchanges per hour. The IICRC recommends three air exchanges per hour for dehumidifiers during mitigation. To determine this number, we must consider the cubic feet per minute (CFM) rating of the dehumidifier. This calculation is less involved since we already know the total volume of the drying chamber. To determine the CFM rating necessary, we can use the following two step process:

• Volume/60 = CFM (Cubic feet needed per minute for one air exchange per hour.)
• CFM*3= Total CFM needed for recommended three air exchanges per hour.

Using our drying chamber volume from the previous example of 4,464 CF, we would calculate the following:

• 4464/60 = 74.4 CFM
• 4*3 = 223.2 CFM for 3 air exchanges per-hour

Most equipment manufacturers publish their AHAM and CFM ratings which makes it possible to determine if the equipment being utilized during a mitigation project is appropriate for the drying chamber.

As a field inspector or desk reviewer, there are many different situations and scenarios you may encounter, even in a single day. While you likely have a good grasp of the technical knowledge necessary for most of the files you review, everyone comes across a file or situation at some point that is unfamiliar to them. Whether you need a refresher on a subject you don’t encounter on a regular basis or would like to gain more knowledge about a topic that your knowledge is limited, Haag Education may be a great resource!

Thomas Culver, CPAU, IICRC- MRS, WRT, FSRT is an experienced Senior Construction Consultant, with more than 20 years in the construction and insurance restoration industries. In addition to WRT and FSRT certifications, Mr. Culver has obtained the IICRC Mold Removal Specialist (MRS) certification, which is the highest level of certification that IICRC offers for mold. Mr. Culver is also an ITC certified thermographer and Part 107 drone pilot. Mr. Culver and Haag Construction Consulting offers expert witness services, written report of findings following a site inspection or review of file documents, and comparative reports and estimates for mold remediation, water mitigation, and repair files for residential and commercial losses.

Mr. Culver is proficient in Matterport, Xactimate, Moisture Mapper, T&M Pro and Xactanalysis Claims Management. His areas of expertise includes construction, restoration, mitigation, remediation, clerk of works, and litigation support. TCulver@HaagGlobal.com

Any opinions expressed herein are those of the author(s) and do not necessarily reflect those of Haag Engineering Co., Haag Construction Consulting, Haag Education, or parent company, Haag Global, Inc.

Does Haag’s Test Square Method Work for Wind-Related Damage?

BY SCOTT BALOT, RRO, SENIOR CONSULTANT, HAAG CONSTRUCTION CONSULTING, AND JONATHAN GOODE, Ph.D., P.E., PRINCIPAL ENGINEER, ASSOCIATE VP OF ENGINEERING

Basic forensic techniques when inspecting for hail-related damages to roof surfaces typically include the method of performing a “test square.”  This method was developed by Haag engineers in the 1960s and is a widely accepted practice to this day and industry standard. (For more information on the history and methodology, see Richard Herzog’s blog post from April 2019. )

The test square works well for hail due to the randomness of hailfall.  Excluding areas that are covered or blocked by obstructions, any one area on the roof has a similar chance of being struck by hail that any other area has on the same roof.  Certainly, there are other variables to hailfall including wind-driven directionality in which hail typically falls and the test square methodology captures this given that test squares are performed on each directional facing slope.

So, what about quantifying wind-related damages in the same manner?  In order to answer that, it is important to understand the two basic types of wind damage that can occur to a roof system.

The first type is called “direct” wind damage.  Direct wind damage consists of material blow-off and material uplift resulting in tears, creases, fastener detachment, or material displacement.  An example would be a creased three-tab shingle.  The second type is called “indirect” wind damage.  Indirect wind damage is experienced when wind-blown debris causes damage upon impact.  An example of this is a satellite dish that is blown over and punctures the roof covering.

Can direct wind damage be quantified using the test square method?

Unlike hail, wind effects on buildings not only vary from the windward slope to the leeward slope, but also differ from the edge of the slopes where materials are most vulnerable to uplift (corners, eaves, rakes), at the top (ridges), and finally to the middle (field).  Installation of roof materials, such as variable fastener placement, condition of materials, such as seal strip bond on asphalt shingles, and slope pitch can also play a role in the effect that wind has on a roof covering throughout each slope.

Because direct wind damages are not consistent throughout each slope, attempting to quantify damages with test squares and extrapolating those results for the entire surface will not accurately represent the number of potentially damaged components.

Can indirect wind damage be quantified using the test square method?

Because indirect wind damage is specific and contained to each item that impacts the roof surface, the only accurate way to quantify indirect damages is on an individual basis and limited to the damages directly caused by wind-blown item.

Conclusion

While the test square method is acceptable for calculating hail-related damages, it is not suitable for determining extent of wind-related damages.  Careful inspection of the entire roof surface should be performed in order to properly assess both types of wind-related damages to obtain accurate amount of area(s) affected.

_________________________

Jonathan S. Goode, Ph.D., P.E., serves as Associate Vice President for Haag Engineering Co. and is a Senior Engineer.  Dr. Goode provides engineering consulting and expert witness services.  He has provided expert testimony in cases involving roof and building envelope performance/damage.  Dr. Goode has presented at various conferences and claims association meeting, as well as chapters of the American Society of Civil Engineers.  Dr. Goode holds B.S., M.S., and Ph.D. degrees in Agricultural and Civil Engineering from the University of Georgia, the University of Colorado at Boulder, and Colorado State University.  He is a licensed professional engineer in 17 states and was an Assistant Professor at Oklahoma State University prior to coming to Haag Engineering in 2010.  Dr. Goode has published papers in several peer-reviewed scientific journals.  Dr. Goode is a member of the American Society of Civil Engineers and serves on the Committee on Forensic Practices in the Forensic Engineering Division.

Scott Balot is a Senior Construction Consultant with Haag Construction Consulting with 20+ years’ experience in the construction and insurance industries. Mr. Balot expertise includes knowledge of wind and hail-related evaluations to a wide variety of commercial and residential roof systems and exteriors. These roof systems include installations on multi-family complexes, industrial facilities, restaurants, hotels, shopping centers, commercial facilities, government operations, residences, and many others. Scott has experience in damage assessment, consulting, estimating, negotiation, and project management. Scott previously worked as a Roof Consultant and a Property Claims adjuster for several independent firms in multiple states. Mr. Balot gained extensive knowledge related to claims practices and adjustment processes, and has worked in major catastrophe (hurricane) environments. He has been involved in both residential and commercial losses ranging from storm-related events to fire, theft, water, and vandalism damages. He has also successfully represented clients in appraisal processes.

Any opinions expressed herein are those of the author(s) and do not necessarily reflect those of Haag Engineering Co., Haag Construction Consulting, Haag Education, or parent company, Haag Global, Inc.

Building Damage Prevention in Unprecedented Years

Taking smart preventative steps to ward off damage, defect and deterioration in buildings has always been within the purview of property owners, managers and insurers.

The year 2020 was one of the most extraordinary years in modern history. As the pandemic continues into 2021, the buildings in which we live, learn and work have seen an incredible change in how they are used and occupied, as well as in the level of physical care and maintenance they receive.

Impact of COVID-19

The impact of the global COVID-19 pandemic on our private, public and professional behaviors in addition to the risks these changes pose to the buildings we inhabit has been unprecedented. Additional significant damage occurred due to increased natural disasters such as hail, floods and wildfires in 2020.  According to Swiss Re, “In the US, a record number of severe convective storms caused devastation throughout the year, likely leading to record annual losses in the country for this peril. Australia and Canada suffered significant losses from hail damage in 2020. Canada experienced its costliest-ever hail event in Calgary in June, which led to losses of USD 1 Billion¹ .”

Changing Behaviors

Because of the widespread restrictions brought on by COVID-19, people are now spending much more time at home as they adapt to remote work arrangements and are simply going out less often to conduct day-to-day activities like shopping and socializing. Even as restrictions start to ease, many employers are allowing employees to continue work-from-home or hybrid arrangements.

For residential buildings, this has translated into a massive increase in load demand on building structures, finishes, HVAC, plumbing, and electrical services. Concurrently, more use requires more care, maintenance, and repairs.  Such continuous use can, for instance, very often result in increased temperature and humidity levels within a building, which not only increases potential health hazards, such as mold, but can also promote a more rapid deterioration of the building structure.  Increased human presence also adds to the chances of accidental fires being caused by activities like cooking or smoking.

Unused Buildings

Because of the pandemic, many non-residential buildings have been experiencing much less human occupancy than usual, with some of them being virtually unoccupied. However, being unused does not mean they need less care.

Buildings are exposed to natural hazards such as wind, snow, rain, freezing or high temperatures. and water flooding, regardless of their occupancy. In fact, fluctuations in temperature and humidity in non-occupied spaces are different than during normal occupancy periods and require specific programs of maintenance and care.

During cold winter months, there is a higher risk of water damage due to pipe bursts caused by sub-freezing temperatures. Large snow accumulations may be expected on the roofs of buildings that are unoccupied and either unheated or nominally heated. In such cases, roof drains may not operate as intended and cause excessive ponding that can lead to excessive loads, roof leaks, and related issues.

During warmer spring and summer months, storm season can bring periods of heavy rainfall. Roofs and gutters should be kept free of leaves and debris which could also clog drains or gutters. Interiors should be climate-controlled to prevent damage to finishes during very hot days in southern latitudes.

Damage Prevention Complications

Without a doubt, the pandemic has created a raft of complications around damage prevention, monitoring and inspection for unoccupied or partially occupied buildings.

One of the biggest increased risks with such buildings is fire. With reduced on-site security, monitoring and inspection, the likelihood of fires being caused by potential trespassers, deteriorated wiring, faulty fire detection systems and sprinklers turned off, damaged, and/or not maintained is much greater than usual.

Making matters worse is that public health restrictions and lockdowns put strain on the emergency services and supply chains, which affected how building operators protect and preserve their properties following climatic events and other damage-causing incidents.

The key saving grace through all this is that such building component failures as described above can be avoided, or damage mitigated, if key warning signs are observed and recognized, and adequate action taken in a timely manner.

Early Warning Signs

Consideration should always be given to any change in a building’s use, particularly if it is expected to occur over a prolonged period of time. The property owner should put in place adequate measures to look out for early warning signs of potential issues. This will reduce the risk of an incident occurring that results in immediate damage, as well as avoiding the potential of additional damage and costly remedial actions over time if the condition remains unnoticed and unattended.

Considering how the widespread impact of the coronavirus pandemic has continued into 2021, it is incumbent upon building property owners to take every preventative step possible to preserve the upkeep of their physical properties, both to protect their investment and to ensure that the structures and the environments they envelope are ready to welcome the world back in when the time is right.

As the famous philosopher Desiderius Erasmus once said, “Prevention is better than cure.”  We have been reminded of this more than ever in order to protect our health. Same applies to our buildings.

1. “Swiss Re Institute estimates USD 83 billion global insured catastrophe losses in 2020, the fifth-costliest on record”, Swiss Re Group. 15 Dec 2020. https://www.swissre.com/media/news-releases/nr-20201215-sigma-full-year-2020-preliminary-natcat-loss-estimates.html

Sasa Dzekic, M.Eng., P.Eng., is the Practice Lead, Civil/Structural Engineering for Haag Canada. Mr. Dzekic has over 30 years of professional experience in structural engineering involving a wide range of building projects. He specializes in investigation and assessment of failures of buildings and structural systems, and/or their components, and evaluation of structural damage. Mr. Dzekic has conducted structural forensic investigation and assessment, preparation of reports, and expert testimony. He has performed planning and on-site advice with respect to unsafe building conditions and demolition, including temporary measures for structural securing of the buildings. He has conducted structural analysis and design of concrete, steel, wood and masonry structures, review of drawings for building permit purposes, and field review during construction.

For more information on Mr. Dzekic or Haag Canada’s areas of expertise, please visit haagcanada.ca.

Any opinions expressed herein are those of the author(s) and do not necessarily reflect those of Haag Canada, Haag Engineering Co., Haag Construction Consulting, Haag Education, or parent company, Haag Global, Inc.

HURRICANE LAURA DAMAGE TO WOOD-FRAMED RESIDENCES

By Tim Marshall, P.E., Principal Engineer, Meteorologist

On August 27, 2020, Hurricane Laura struck southwest Louisiana and extreme southeast Texas.  Emeritus Engineer and Meteorologist experienced the hurricane firsthand in Lake Charles, LA then spent three days conducting a damage survey. The primary purpose of the damage survey was to evaluate the performance of various structures that experienced strong winds. This blog will focus on wind damage to residences.

Hurricane Laura made landfall at Cameron, LA around 0600 Universal Time Code (UTC) on August 27, 2020.  According to the Lake Charles National Weather Service (NWS), Laura was the strongest hurricane to strike southwest Louisiana since records began in 1851. The hurricane moved due north toward Lake Charles at about 4.5 m/s (10 mph) weakening slowly.  The NWS in Lake Charles recorded the highest wind gust of 116 kt (133 mph) out of the east at 0732 UTC before the wind equipment failed.  However, the Florida Coastal Monitoring Program (FCMP) erected a portable tower at Chennault International Airport on the east side of Lake Charles and had obtained a continuous wind record with peak wind gust of 115 kt (132 mph) out the east at 10 m (33 ft).  A second FCMP site in Sulphur, LA recorded a peak wind gust of 96 kt (110 mph) from the east also on a 10 m (33 ft) tower.

There was widespread wind damage to residences in the Lake Charles area particularly to roof coverings.  In some cases, homes experienced structural damage when conventional toenailed roof structures failed aided by broken windows or doors on the windward sides of buildings which increased internal wind pressures.  In addition, trees fell on many homes causing structural damage.  Commonly observed problems were improper attachment of roof coverings especially when asphalt shingles were nailed too high above the sealant strips.  Some fasteners were overdriven tearing through the shingles.  Shingles typically were fastened with four nails per shingle instead of the required six nails for hurricane prone areas.  The combination of high nailing, overdriven fasteners, and fewer fasteners than required resulted in less than half the required number of fasteners in the shingles to resist wind uplift.  As a result, there was widespread wind damage to asphalt shingle roofs particularly on windward slopes.  Wind damage included combinations of flipped, creased, torn, and removed shingles.  Asphalt shingle roofs that were nailed correctly sustained far less wind damage than those roofs that were not installed correctly. Loss of roof coverings and underlayment allowed water ingress which greatly increased the amount of interior damage to residences.  Refer to Figure 1.

The vast majority of residences had Degrees of Damage (DoDs) of 4 or less on the Enhanced Fujita or EF-scale with damage limited to roof coverings and cladding items.  A small percentage of homes experienced DoD 6 damage where they had windward windows or garage doors fail allowing internal pressures to help lift and remove the roofs.  Refer to Figure 2.  Expected failure wind speeds for DoD 4 damage is around 43 m/s (97 mph) where expected failure wind speeds for DoD 6 is around 55 m/s (122 mph).  Thus, we found the wind speeds listed in the EF-scale agreed well with the DoDs and locally measured wind speeds.   See Table 1.

Where roof failures occurred, there was no evidence of metal straps or clips used to attach rafters to wall top plates.  Roof failures initiated where rafters were toenailed to wall top plates.  Nails were simply pulled out of the wood.  No doubt such roof failures would have been prevented had steel straps been installed properly as these connections can exceed 1000 lbs. whereas toenailed connections with 16d nails have an average pull out strength of about 300 lbs.   The vast majority of homes that were better built (continuous load paths that were well anchored) were able to survive a major hurricane.

Figure 1. Typical wind damage to asphalt shingle roof coverings on residences.  The inset image shows high nailing (yellow circles) with nails missing the top laps in the overlying shingles (red circles).  

Figure 2.  House in Vivian, LA which lost the entire roof structure.  The front side of house faced north and was windward to the strongest winds.  Failure of the front doors and windows allowed internal pressure to help lift the roof.  Inset image (A) shows upside down roof in the backyard with “birdsmouth” cut outs in rafters (circled) and close-up of broken toenailed connection (B) where two parallel rust stains indicated where nails had been.

Table 1.  DoDs for residences from the EF-scale document.

By Tim Marshall, P.E., Meteorologist, Haag Principal Engineer

Tim Marshall is a structural engineer and meteorologist.  He has served as a Haag Engineer since 1983, assessing damage to thousands of structures (particularly damage caused by wind and other weather phenomena). He has written numerous articles, presented countless lectures, and appeared on dozens of television programs in order to share his extensive knowledge re: storms and the resultant damage.  He is a primary author of many Haag Education materials, including the Haag Certified Inspector-Wind Damage course.  He is also a pioneering storm chaser and was editor of Storm Track magazine.  See his profile here.

Any opinions expressed herein are those of the author(s) and do not necessarily reflect those of Haag Engineering Co., Haag Construction Consulting, Haag Education, or parent company, Haag Global, Inc.

The Insurance Industry’s First-Ever Inside Adjuster Certification – NEW from Haag Education

Haag Education is once again setting the bar for science-based damage training in the insurance industry with an all-new, first-of-its-kind certification designed especially for inside reviewers/desk adjusters, underwriters, or anyone who works or estimates claims from behind a desk!  Introducing the Haag Certified Reviewer (HCR) program!

Haag certification is the most sought-after adjuster/industry training for adjusters, roofing consultants, contractors, and engineers—professionals who assess damage in the field.  Haag certification training has set the standard for roof and building envelope damage assessment since its introduction in 2007, with over 20,000 certifications earned by industry professionals.

Recent trends in the US and Canadian markets are fewer and fewer licensed adjusters in the field. Inspections are often being done by third-party inspection companies who document the damage and provide reports from the field to decision-making adjusters working inside, behind a desk.   Carriers and independent adjusters have emphasized there is a great need for specialized training geared towards adjusters who may not have the benefit or ability to see the claim firsthand in the field. Haag Education has answered the call and is excited to deliver this one-of-a-kind certification training backed by Haag’s reputation and nearly 100 years of damage assessment expertise.

The Haag Certified Reviewer – Residential program was rolled out in March 2021, and has received stellar reviews already.

HCR will allow any student to complete up to 4 levels of certification and requires NO EXPERIENCE in construction or claims or damage assessment!  Every HCR course within the curriculum is taught from the perspective of an inside reviewer/adjuster.  HCR is delivered 100% on-demand so you can complete each level on your schedule!  The introductory price of only $349 per certification level makes this an affordable option to help further your knowledge and career.

What are the 4 levels of HCR-Residential certification?

• Level I – Weather, Basic Residential Construction, Residential Roof Installation Basics *NOW AVAILABLE
• Level II – Damage Assessment *NOW AVAILABLE!
• Level III – Estimating Basics, Interior & Exterior estimate writing & review (Xactimate & Symbility optional tracks) – * Available Summer 2021
• Level IV – Advanced (made up of advanced level courses that the student may choose from) – *Available Summer 2021

Each HCR-R level takes about 12-18 hours to complete.  The first three levels culminate with an online, proctored, open-book exam, which attendees must pass with a score of 80%+.  A Certified Reviewer earns their Level IV certification once they’ve completed a 12+ hours of advanced-level courses and passed the necessary course exams.  We are currently applying for continuing education credit for HCR courses.  Stay tuned for more details!

Development of the HCR-Commercial program is scheduled to begin in late 2021, with rollout scheduled for late 2022.   The HCR-Commercial certification will focus on commercial building construction types, damage assessment, and estimating damage basics with Symbility and Xactimate.

For more information on the Haag Certified Reviewer program including details and descriptions of each level, please visit our HCR website.

Ryan Holdhusen oversees the management and strategic growth of Haag Education. He manages Haag’s line of seminars, certification programs, and products/tools. He assess product concept, development, marketing, sales and operations. Ryan has been with Haag since May 2002.

Any opinions expressed herein are those of the author(s) and do not necessarily reflect those of Haag Engineering Co., Haag Construction Consulting, Haag Education, or parent company, Haag Global, Inc.