Disaster Safety Review 2011 - Vol. 1

Disaster Safety ReviewIBHS RESEARCH CENTER: A REMARKABLE FIRST YEARPAGE 2

HIGH WIND TESTING:COMMERCIAL FOCUSPAGE 4

MASTERING MOTHER NATURE’SMENACE: HAILPAGE 6

NEW RESEARCH REPORTS:EMBERS AND RADIANT HEATPAGE 9

INSIGHTS ON PREVENTINGWIND-DRIVEN WATER ENTRYPAGE 16

2011 • Volume 2

INSURANCE INSTITUTE FOR BUSINESS & HOME SAFETY’S

2 Disaster Safety Review | 2011

President’s LetterAs was the case for the entire property insurance industry of which the Insurance Institute for Business & Home Safety (IBHS) is a part, the past 12 months were clearly defined by a plethora of natural disasters occurring in every corner of the U.S.

For IBHS specifically, this meant a full slate of proactive and reactive research, education and communications initiatives tied to everything from the early-arriving, record-setting cold, snow-filled winter; to the early-arriving, record-setting wildfire season in the Southwest; the early-arriving, tragically severe, record-setting thunderstorm and tornado season; more than one instance of extensive, slow-motion flooding in usual and unusual regions; earthquakes in atypical locations; a second round of severe wildfires that claimed hundreds of homes in the Southwest; and, Hurricane Irene and Tropical Storm Lee – both of which inflicted substantial losses and added more lives lost to the terrible toll inflicted by catastrophes earlier in 2011.

On the much more positive side of the ledger, the past 12 months was truly remarkable for IBHS because in October 2010 our multi-hazard Research Center in South Carolina opened its doors to the public. Since then, we have begun executing several meticulously planned residential and commercial building science programs. Many of the research outputs have been translated into well-received, digestible information and visuals directed at the public. Other outputs have been reserved for the broader research community, which has enthusiastically cheered us on.

To date, our successes at the Research Center include (in somewhat chronological order):

• Creating and validating lab capabilities to closely mimic several types of wind storms (e.g., Category 1, 2 and 3 hurricanes; extra-tropical storms; and frontal winds associated with thunderstorms). This work includes the ability to repeat and control wind gust structures, pressures, speeds, and the type of flow separation and reattachment observed in real world storms and simulated in boundary layer wind tunnel studies that are the basis for most building code provisions.

• Creating and validating laboratory wind-driven “rain”-making capabilities, including accurate representation of water droplet size, shape and distribution measured in hurricanes and other severe wind storms.

• Creating and validating laboratory wildfire ember storm and radiant heat capabilities. This includes generating properly distributed and sized firebrands (e.g., smaller embers of the kind typically blown or drawn into building openings, and larger embers that often land on combustible material on or near the structure and ignite spot fires).

Julie A. Rochman President & Chief Executive Officer Insurance Institute for Business & Home Safety

Editor Candace Iskowitz

Art Director Amy Kellogg

Editorial Office 4775 E. Fowler Ave., Tampa, FL 33617 E-mail: [email protected] Phone: (813) 675-1047 Fax: (813) 286-9960

Disaster Safety Review is published by the Insurance Institute for Business & Home Safety (IBHS) to further its mission to conduct objective, scientific research to identify and promote effective actions that strengthen homes, businesses, and communities against natural disasters and other causes of loss. Statements of fact and opinion contained in articles written by authors outside IBHS are their responsibility and do not necessarily reflect the opinion of IBHS or IBHS membership.

ISSN 1537_2294 Copyright IBHS 2011

CONTENTS

2 PRESIDENT’S LETTERJulie Rochman

4 IBHS RESEARCH CENTER WILL STRENGTHEN BUSINESSES ACROSS AMERICA Debra Ballen

6 IBHS RESEARCH CENTER: HAIL RESEARCH PROGRAM UPDATETanya M. Brown, Ph.D. and Anne Cope, Ph.D., P.E.

9 IBHS RESEARCH CENTER REPORT: RADIANT PANEL TESTINGStephen Quarles, Ph.D.

12 IBHS RESEARCH CENTER REPORT: EMBER STORM TESTING Stephen Quarles, Ph.D., and Anne Cope Ph.D., P.E.

16 IBHS RESEARCH CENTER REPORT: HURRICANE WIND-DRIVEN RAIN TESTINGTimothy A .Reinhold, Ph.D, P.E.; Stephen Quarles, Ph.D.; Anne Cope Ph.D., P.E.; Tanya Brown Ph.D., and Zhuzhao Liu, Ph.D.

3Disaster Safety Review | 2011

• Graphically demonstrating the life safety and economic value of properly tying a residential structure together to resist high winds.

• Identifying, evaluating, and finding a simple, inexpensive and workable solution to a previously unrecognized failure mode for residential construction subjected to high winds and pressurization.

• Attracting a tremendous amount of positive public and (new and traditional) media attention for IBHS and the property insurance industry.

• Conceptualizing and fabricating a variety of instrumentation and sensor packages, as well as delivery systems for physical testing of components and systems where no relevant protocols existed.

• Partnering with the U.S. Department of Homeland Security, U.S. Forest Service, and Savannah River National Laboratory to evaluate and demonstrate the dangers associated with more than one dozen potential wildfire ignition points found in typical residential construction.

• Clearly demonstrating why and how sealed roof decks and other mitigation measures that are part of the IBHS FORTIFIED criteria can prevent extensive interior damage to houses subjected to high winds and wind-driven water. Data and learning from these tests are being fed into IBHS code improvement submissions and being used in other venues to educate the building industry and consumers about relatively inexpensive ways to seal roof decks and reduce water intrusion.

• Beginning a long-term investigation focused on wind performance of asphalt shingles, including testing to characterize flow and pressures on typical gable and hip roof residential structures using two different slopes;

for these tests, Research Center staff have created unique load-measuring devices.

• Initiating a long-term project examining major commercial rooftop equipment performance issues; initially determining wind loads on equipment depending on shape, size, location and configuration; then assessing typical anchorage systems and guidance.

• Making great progress toward being able to manufacture, store and correctly propel/deliver large batches of hailstones with the proper density, hardness and varying sizes. (Believe me when I say that this is our biggest challenge thus far. No one has ever created an actual hailstorm indoors, and it is very, very complicated to get right.)

As is the case with making hailstorms, behind each one of the accomplishments above lies many months of work, along with stops and starts as we figured out how to do things for the first time.

Regardless of the challenges, it has been, and remains, absolutely essential that IBHS lay a rock solid foundation for our research going forward. If our supporters and critics do not agree that our methodology and protocols are valid, our research would be tainted and could easily be dismissed. That is precisely why we have spent so much time getting the science exactly right.

Some of the accomplishments listed above are covered in this issue of Disaster Safety Review (DSR). Several articles detail IBHS programs focused on wind, water, hail and fire – the four hazards at the center of IBHS Research Center physical testing programs. In addition, this DSR includes an interesting case study on how planning can reduce losses from fires following earthquakes, and a piece describing how the IBHS laboratory research will strengthen

businesses across the nation. We also have an update on building codes.

Looking ahead, we know that each year to come holds the potential to rack up new records for property destruction and loss. IBHS is prepared to drive Mother Nature’s statistics down by building on the sound scientific base established at the Research Center this past year. As always, we look forward to working closely with our members and other allies to meet the needs of the residential and commercial policyholders in whose interest we aggressively pursue answers and workable solutions.

Julie RochmanIBHS President and Chief Executive Officer


October 2011 marks the one-year anniversary of the opening of the Insurance Institute for Business & Home Safety (IBHS) Research Center in South Carolina. The IBHS Research Center provides unprecedented opportunities for objective laboratory testing of full-scale, one- and two-story residential and commercial structures (as well as components that will be used in larger commercial facilities) in conditions that mimic the varied, and sometimes extremely high-speed, wind events that occur in the real world. The Research Center also has developed capabilities for simulating wind-driven rain and wind-driven wildfire embers as they occur in the real world. Scientists at the lab currently are working to develop and validate hailstorm simulation capabilities. By finding out how buildings come apart, IBHS can better determine how to keep them together, or put them back together again – safer and stronger than they were before.

Since the Grand Opening events, there has been extensive newspaper, online, radio and television media coverage of how testing at the IBHS Research Center will help homeowners protect their property against nature’s fury.

This article looks at some of the unique ways in which the IBHS Research Center can advance building science as it relates

to commercial risk

management, in order to help all those in the commercial risk chain improve their outputs and strengthen their bottom lines.

RECREATING NATURE IN THE TEST CHAMBERThe centerpiece of the Research Center is a unique wind tunnel with a large fan array and contraction mechanism, consisting of 105 variable speed fans. Each fan measures nearly 6 feet in diameter and is equipped with a 350 hp motor. When running at full capacity, the fans can create a flow volume equal to 20 times the flow going over Niagara Falls, producing winds up to about 130 mph, or the equivalent of a Category 3 hurricane, as well as gust structures associated with extra-tropical winds (e.g., the passage of a frontal system or a Nor’easter).

This baseline wind capability has been augmented by:

• mulch burning equipment to create embers typical of a wildfire, which are ducted into the wind stream to create realistic wind conditions that occur during a wildfire ember attack on a property; and,

• an array of 450 nozzles carefully designed to produce a uniform distribution of up to and exceeding eight inches of “rain” per hour with

droplet size distributions that match those measured in hurricanes and thunderstorms. This system allows observation of how water penetrates the building envelope and ruins interior components and contents.

Currently under development is the capability to recreate actual hail storms using hailstones of the right size and density, propelled at the correct vertical velocity that can be combined with realistic thunderstorm winds.

Among IBHS’ highest initial priorities has been to scrupulously calibrate the test chamber to control for wind speeds and proper aerodynamic flows, along with other validation procedures for wildfire ember generation and torrential rain. A similar validation process is underway for hail simulation capabilities. The scientific expertise underlying the lengthy validation process should provide insurers and risk managers – as well as the construction industry and public policymakers – with confidence that the results they see from the lab accurately replicate real world weather conditions that business owners are likely to encounter.

IBHS Research Center Will Strengthen Businesses Across America

By Debra Ballen, IBHS Senior Vice President of Public Policy and General Counsel


UNIQUE COMMERCIAL TESTING CAPABILITIESThe massive size of the test chamber allows for testing of one- and two-story commercial structures (a variably dimensioned 30 ft X 40 ft total footprint is presently being used) that include design features, materials and components of buildings that commonly house a variety of small- to mid-sized businesses, such as small office buildings, strip shopping centers, or franchise restaurants. Examples of typical commercial construction techniques that can be incorporated into the specimens include flat roofs with steel decks on steel bar joists with commercial roof covers (e.g., single-ply membranes).

In addition, test specimens may include significant components of larger commercial facilities – for example, rooftop equipment of the kind seen most commonly on industrial and office buildings, hotels and apartment buildings, and shopping centers. Historically, this kind of testing has required exceedingly small scale models (1:50 to 1:200) in typical boundary layer wind tunnels. At these scales, simulation of all of the important flow features and effects is generally impossible and additional computational work is needed to assess the impact of simulation distortions on load information that has been included in building codes and standards.

In its design and operations, the IBHS Research Center complements loss prevention research and product testing

currently conducted at the FM Global Research Campus in Rhode Island, as well as at several leading universities in the United States, Canada, and internationally. IBHS is coordinating its own efforts with colleagues at these institutions to maximize synergies and avoid duplication.

In the future, it may also be possible to test a much broader array of commercial structures, such as agricultural outbuildings, and larger structures and arrays of rooftop and ground-mounted systems using 1:3 to 1:10 scale models, in order to assess their damageability in severe weather. This is because the test chamber and its major components (i.e., access doors, overall dimensions, and turntable) have been designed to provide maximum flexibility for the types of specimens that can be tested. The results from these tests will help risk managers reduce property losses to the structures themselves, and in many cases, to contents as well.

ADDRESSING MAJOR DRIVERS OF COMMERCIAL PROPERTY DAMAGECommercial rooftop equipment testing was chosen as a subject for some of the earliest testing at the IBHS Research Center because it is a significant cause of property insurance loss. This includes damage to the equipment itself; interior water damage that can occur if damaged equipment results in penetration of the roof deck; and, structural damage that can occur if detached equipment becomes airborne. The types of

equipment to be tested (e.g., HVAC systems, package units, condensers, duct work, etc.) were selected in consultation with IBHS member company experts, based on the frequency and severity of insurance claims in which they are involved. Likewise, testing parameters such as equipment dimensions, anchorage, spacing relative to the roof, and location of specimen on the roof, will mimic situations most likely found in real world installations.

GOING GREEN AND BUILDING STRONGThe popularity of “green” or sustainable building design and construction among business owners has continued even during the recent recession. Green building practices are intended to provide meaningful environmental benefits but must not compromise a business’s resistance to natural hazards such as high winds, earthquakes, floods, or wildfires. That is why an early focus at the IBHS Research Center will be on the wind resistance of photovoltaic equipment increasingly being used by businesses to improve energy efficiency. IBHS’ goal is to help businesses combine durability and sustainability in a way that is both economically and environmentally sensible. Other potential testing geared to combining strength and sustainability includes green roofs; disaster resistance of individual LEED® elements (e.g., foam sheathing insulation); and analysis of products and construction techniques that leads to development of new

Continued on page 22

6 Disaster Safety Review | 2011Disaster Safety Review | 2011

By Tanya M. Brown, Ph.D. and Anne Cope, Ph.D., P.E.

Researchers at the Insurance Institute for Business & Home Safety’s innovative lab in South Carolina have begun the complicated task of recreating one of nature’s most damaging forces in a controlled setting.

INTRODUCTION TO CURRENT TEST STANDARDS FOR HAILIBHS researchers have begun recreating realistic hailstones in a laboratory setting. Current test standards utilize steel balls or pure, freezer ice balls. Each of these has strengths and weaknesses in terms of testing building products. The steel balls are used in a simple drop test, which is easily repeatable with minimal effort and expense. The steel ball test method matches the kinetic energy of a similar-sized hailstone, by dropping the steel balls, which are much heavier, harder, and denser than hailstones, from the necessary height to achieve the correct kinetic energy. The drop distance is relatively short, as reaching terminal velocity is not necessary since the steel balls are so much heavier than hailstones. The primary criticism of this kind of method is that the reaction of a steel ball is much different than the reaction of a hailstone upon impact. This is because a hailstone will often deform, crush, or shatter upon impact, while a harder steel ball will not. Furthermore, the damage pattern caused by the steel ball striking a shingle looks very much like that created by a ball peen hammer.

In the test standard that utilizes freezer ice balls, the balls are shot or propelled to their terminal velocity to impact the building products. The ice balls are created by pouring water into spherical molds and freezing them until solid. The freezer ice balls that are used are

more realistic in terms of their reaction upon impact; they tend to shatter or disintegrate upon impact, as natural hailstones would do. However, like the steel balls, they are denser than natural hailstones, although to a lesser extreme. This means the impact energy of a freezer ice ball, which is propelled at the terminal velocity for an identically-sized natural hailstone, is different from that of a similar-sized natural hailstone. Freezer ice balls are also harder than naturally occurring hailstones. It is also difficult to create mass quantities of these freezer ice balls because it requires someone to make them one batch at a time. Furthermore, they must be used quickly (within a week) before sublimation and shrinking occurs in the freezer, and should also be used before melting occurs (within a minute) once they are removed from the freezer for testing.

CREATING REALISTIC HAILIBHS is developing the capability to replicate both the steel ball drop test standard and the ice ball propulsion standard. The primary method to be used in our own testing program will be ice ball propulsion using a variety of devices. However, the first step is creating more realistic hailstones than those currently used in the ice ball test standard. IBHS has developed an experimentation process, in which varying methods are employed to alter the structure of the hailstones. Naturally occurring hailstones are typically less

dense than pure ice, because they

contain layers of air bubbles. They are also typically softer than pure ice. IBHS is striving to replicate these qualities, while still preserving the ability to manufacture dozens at a time. The initial hailstone size used for experimentation is 1 inch in diameter, which is the criterion for severe hail as defined by the National Weather Service [1]. Once the density experiments are complete, the methods can be expanded to the larger hailstone sizes. IBHS is planning to test up to 3-inch spherical hailstones,

Hail Research Program Update

IBHS RESEARCH CENTER REPORT:


although larger conglomerate hailstones are planned for the future.

One of the biggest questions that still must be answered relates to the hardness of hailstones. In the literature, hailstones are usually referred to as “hard” or “soft”, yet there are no quantitative ways exist to distinguish these categories and researchers must rely on the qualitative look and feel. IBHS engineers have begun brainstorming ways to quantitatively distinguish varying levels of hardness in hailstones. Hardness quantification methods for other materials, particularly building

materials, such as metals and concrete are being investigated to see how they might be adapted for use in hailstone hardness determination. This will also require field research to measure the hardness of actual hailstones to build up a statistical database, for various storms and different sizes of hailstones.

REPLICATING THE CURRENT TEST STANDARDSOver the past year, the lead IBHS hail engineer Dr. Tanya Brown has visited several research labs to learn from the knowledge and experience that already exists on hail impact testing, and particularly to learn about the shooting or dropping methods for hailstones that are being used by others. IBHS will be conducting tests using both existing methods and comparing those

results to in-house methods, to see how the damage differs and to

identify improvements that will produce a closer match

with field observations. The hail design team

is investigating various devices

commercially available or available from other labs

to complete the ice ball

propulsion testing. The speed, power, and accuracy of such devices are critical for impact

testing. The speed must be adjustable to account for the

terminal velocity of the different sized stones, which ranges from about 25 mph for the smallest, lightest hailstones up to about 90 mph for the largest, heaviest hailstones. The ideal device must be powerful enough to reach the high speeds necessary for the larger hailstones; adjustable or easily modified to account for the various diameter hailstones, and capable of propelling irregularly-shaped hailstones that will be utilized for testing in the future. In addition, the design team will be creating a steel ball drop test device that is custom-fit in the small specimen laboratory space available at the IBHS Research Center.

BATTER UP!Because of the need to shoot large quantities of hailstones within the large full-scale test chamber, the design team is investigating the use of a variety of systems including a hopper-fed baseball pitching machine. These are the type of machines used by baseball teams for batting practice and are commonly used at batting cages. They can house a large number of balls in the hopper, so there is a large amount of time between refills, and they shoot at regular intervals, but provide some randomness in the locations of the thrown ball. The machine uses an “arm” attached to a wheel that slowly turns the

The hail design team conducts preliminary testing with the pitching machines.



arm forward 180 degrees as the tension in a spring is tightened, then whips forward the remaining 180 degrees to throw the ball when the spring tension is released. The machine is designed so that modifications to the pitching mechanism can be made to raise and lower the height of the propelled ball (or in our case hailstone), and the spring can be tightened or loosened to increase or decrease the speed of the throw. In addition, the cable connecting the arm wheel to the spring can be tightened and loosened to change the throwing speed.

The IBHS design team is conducting repeatability tests by slightly changing a setting on these mechanisms and throwing numerous baseballs while collecting speed information with a radar gun, and noting impact locations. The settings are slightly modified and the tests are repeated to calibrate the differences created by each minor adjustment in the settings. The settings for each desired speed and throwing height are being tested and marked on the machine in preparation for the hail impact testing. In addition to calibrating these mechanisms, the design team is in the process of modifying the machine so that hailstones smaller than the size of a baseball can be used without slipping

through the machine. This requires modification of the “hand” which cups the ball to throw it forward, as well as a disc which holds the ball in place before the pitching arm swings forward and propels it.

In addition to modifying how the machine throws the balls, the design team will need to modify it to keep the hailstones cold. In the preliminary testing that has been completed with the pitching machine, the team has found that the hailstones begin melting so quickly that they must be hand-fed into the machine one at a time, staying in the freezer until seconds before they are thrown. In order to take advantage of the hopper to feed a large number of stones automatically, the machine will have to be modified to cool and insulate the hopper while each hailstone waits its turn to be thrown.

Other designs for injecting a large number of hail stones of various sizes into the large test chamber are also being evaluated, including an auger-fed air duct where the flow of air through the duct accelerates artificial hail stones to the desired release velocity.

DALLAS-FORT WORTH, TEXAS HAILSTORM INVESTIGATIONFIELD RESEARCHA recent hailstorm in the Dallas-Fort Worth metroplex provided an opportunity for IBHS engineers Rem Brown, Dr. Tanya Brown, Wanda Edwards, and Chuck Miccolis to participate in a damage survey through the Roofing Industry Committee on Weather Issues (RICOWI). The primary goal of the survey was to determine how impact-rated roofing products performed as compared to standard products. This hailstorm in May affected a large area of the metroplex, and hail sizes ranged from about ½ inch to 4 inches. The RICOWI teams spent three days surveying numerous roofs for signs of damage. The teams surveyed both residential and commercial structures, and surveyed numerous types of roofing systems and products. Both new and old construction were surveyed, and the teams were spread throughout many communities in the metroplex. The teams collected basic roof information such as the roof slope and covering material, and collected damage data, such as the number of impacts in a test square, and the types of damage. These data were compiled into a database, and RICOWI will use these

(Left) IBHS Commercial Lines Engineer Chuck Miccolis measures impact sizes on the roof of a commercial building. (Right) IBHS Research Engineer Dr. Tanya Brown inspects hail damage in the valley of an impact-rated roof following the May hailstorm in Dallas.


9Disaster Safety Review | 2011 9Disaster Safety Review | 2011


Figure 1. The IBHS Research Center radiant panel consists of 50 infrared natural gas burners. The panel in this photograph is “on”.

By Stephen Quarles, Ph.D.

Building ignitions during wildfires occur when a component of a home or building is exposed to one or more of the three basic wildfire exposures:

1) burning embers (also called firebrands), 2) direct flame contact, and 3) radiant heat.

Burning embers are the most important cause of home ignitions. When they land near or on a building they can ignite nearby vegetation or accumulated debris on the roof or in the gutter, or enter the building through openings (an open window or vent for example) and ignite furnishings in the building or debris in the attic. Near-building ignitions will subject some portion of the building to either a direct flame contact exposure, where the flames actually touch the building, or a radiant heat exposure, the heat you feel when standing near a campfire or fireplace. The vulnerability of a building to radiant heat depends on the intensity and duration of the exposure. CONTINUED »


IBHS’ general research objective is to conduct scientific studies to identify effective actions that strengthen homes and businesses against natural disasters. For the initial series of wildfire studies, IBHS partnered with Savannah River National Laboratory, USDA Forest Service and Clemson University. The focus of the research is a project funded by the United States Department of Homeland Security Science and Technology Directorate and its Wildland Ignition Resistant Home Design (WIRHD) Program. This collaborative effort helped to develop some basic wildfire research capabilities at the IBHS Research Center and produced information and videos to be used in the WIRHD Program. Although both ember (firebrand) and radiant exposure capabilities were developed as part of this program, the focus of this article is on radiant panel testing.

The most important reason for this project was to provide response data, and video and photographic content needed for the building assessment software tool (to be called the WildFIRE Wizard). This will be the principal product delivered by this phase of the WIRHD Program. In addition to video and photographic content, IBHS was able to collect temperature and heat flux data for windows and selected siding products exposed to radiant heat.

Human skin is much more sensitive to radiant heat than most building products. Whereas skin can develop severe burns in a matter of seconds when exposed to 15 Kilowatts per square meter (15 kW/m2), wood can withstand 20 minutes or longer of that exposure

before igniting. Therefore, the radiant heat level has to be high enough, and the exposure period long enough, for combustible building products to ignite or suffer other forms of degradation, such as breaking glass in a window. Exposure to lower levels of radiant heat can pre-heat a material, making it easier to ignite from a direct flame contact exposure. IBHS is interested in understanding the sensitivity of exterior-use construction products to radiant heat. This is because, for example, once siding ignites, flames can either enter the building through the stud cavity and / or spread vertically up the wall, impinging on and possibly breaking glass in a window glass or entering the attic by burning through materials in the eave. Once the glass in a window breaks, embers can readily enter the occupied space of the building and ignite interior furnishings.

RADIANT PANELThe radiant panel tested at the IBHS lab is 50 inches wide and 63 inches tall (shown on the cover page of this article). It consists of 50 infrared natural gas burner heads arranged in five rows of ten burners each. The surface temperature of each burner is approximately 1700°F (925°C). The radiant heat exposure to the target material was adjusted by moving the target closer to or further away from the radiant panel. In order to calibrate the radiant panel, heat flux sensors were embedded in a ceramic fiber (noncombustible) rigid panel (Figure 2). This panel was moved relative to the radiant panel, and at each location, the radiant heat was measured by the sensors. Results of the calibration testing showed that a 15 kW/m2 and 35 kw/m2 exposure was obtained at separation distances of 40 inches and 20 inches respectively. Most of the tests were conducted at the 35 kW/m2 level, but testing involving corner sections (e.g., an eave or interior corner wall test) were conducted at exposure

levels of about 20 kW/m2. The lower level was necessary because of the increased distance between the radiant panel and the corner of the assembly.

WINDOW TESTSTests were conducted for windows that used different framing materials, including wood, vinyl and aluminum, and different kinds of glass, including annealed (single and dual-pane units) and tempered (dual pane). Window “failure” can occur if the glass breaks or falls out, as already stated, or if the framing material ignites and the fire burns through the material into occupied space of the home or business. Testing at other research labs has indicated that the glass is the most vulnerable part of a window. Results of the IBHS testing support that finding. More importantly, IBHS’ findings support the use of dual-pane windows in that the outer pane usually failed first, and then the inner pane at a later time, if at all. At the 35 kW/m2 exposure, neither of the panes in dual-pane tempered glass windows broke during the 25 minute exposure.

Although other testing conducted separately on glass and curtain materials indicates that curtains located behind

Figure 3. The cotton curtain shown in this photograph ignited more than a minute after the upper section of the window fell out. The stand behind the burning curtain holds the heat flux sensors. During the test, these sensors are positioned directly behind the upper and lower window sections.

Figure 2. Heat flux sensors were embedded at uniform locations in the ceramic fiber calibration panel. Be-tween exposures, this panel was relocated to different distances from the radiant panel (the rear of the panel is on the left in this photograph).


annealed glass and tempered glass commonly used today will not ignite before the window breaks, one objective of the IBHS tests was to demonstrate this in a laboratory. IBHS did this using a vinyl frame, dual pane annealed glass window, at the same 35 kW/m2 exposure. As shown in Figure 3, the curtain will ignite, but this occurred more than a minute after the upper section of the window fell out. The lower section stayed intact during the test. This result supports the pervious testing conducted separately on individual components – the glass breaks first, and then the curtain ignites.

Another goal of the window testing was to evaluate the contribution of screens in reducing the amount of radiant heat that is transmitted into the building. Vinyl-frame, single-hung, dual-pane annealed glass windows were used for these tests, which evaluated the effects of both plastic-clad glass fiber and metal screens. The heat flux sensors were positioned behind the upper and lower sections of the windows. The screens were only positioned in front of the lower section since it was the only section that could open. Results of these tests are shown in Figure 4.

The data from the heat flux sensors behind the screens are the lower two graphed lines in Figure 4. These results showed that window screens absorb radiant heat and thereby reduce the amount that is transmitted through the glass into the occupied (living) space, in this case by about one-third. There

are two other interesting observations that can be seen in this graph. First, note that the measured heat flux behind the unscreened windows was less than 12 kW/m2, indicating that the glass was effective in reflecting or absorbing radiant heat. Second, the plastic clad glass fiber screen seemed to do a slightly better job than the metal screen, indicating that the metal screen may re-radiate heat back towards the window.

SIDING TESTSThe wood siding products subjected to the radiant panel exposure all ignited in times that ranged from about 4.5 minutes to 16 minutes. Such a range in ignition times is not uncommon, particularly given that the updraft created by the volatile gases coming off of the wood and wood-based siding products extinguished the pilot flame located at the top of the wall sections. The time to ignition for the painted products was faster than that for the unpainted products, and the time to ignition for the flat profile products (in this case the plywood T1-11 panelized siding products) was faster than that for the profiled siding product (in this case a solid wood horizontal lap siding with a bevel profile).

Two different vinyl siding products were tested, including a standard product and a “heavy” product. These products differed in their thickness, with the “heavy” product being about 0.01 in. thicker than the standard product. The response of both of the vinyl siding products to the imposed radiant exposure was similar. Neither ignited in flaming combustion, but both started deforming immediately, exposing the underlying sheathing material about a minute into the test (Figure 5).

IMPLICATIONSThe 35 kW/m2 exposure level used in this series of experiments is relatively high. USDA Fire Science Researcher Jack Cohen reported in 2004 on a component of the large international crown fire modeling experiments that took place in the Northwest Territories, Canada between 1997 and 2000. As part of that larger study, Cohen set up wall assemblies at fixed distances from the edge of the burn plots. These assemblies Figure 5. As shown here, the vinyl siding deformed and fell away when exposed to the heat from the radiant

panel, exposing the underlying wall (oriented strand board) sheathing.

Hea

t Flu

x, k

W/m

2

Time, s

Radiant Exposure: 35kW/m2

12

10

8

6

4

2

00 100 200 300 400 500 600

Figure 4. This illustrates the effect of screens on the transmission of radiant energy through a dual-pane window. The upper-most (black) line is from the win-dow that was used in the curtain ignition test.

No screen

Metal Screen

Fiberglass Screen

No Screen - Curtain



By Stephen Quarles, Ph.D., and Anne Cope Ph.D., P.E.

In the 2011 Disaster Safety Review, Vol. 1, IBHS presented an introduction to the Research Center wildfire testing and capabilities. As stated in that article, the primary objective of the testing is to reduce the likelihood of wildfire spreading to buildings in communities in wildfire-prone areas. IBHS has taken steps to meet this objective by developing the capability to simulate a full-scale, wind-driven ember attack on buildings in the IBHS Research Center’s test chamber. In addition, as discussed in the “Radiant Panel Testing” article in this issue, IBHS has also designed and built a radiant panel as part of its research effort to study and understand the vulnerabilities of buildings subjected to wildfire exposures.

This article provides a summary of, and some of the lessons learned (and maybe confirmed) from this recent ember exposure study. This summary is presented using photographs taken during the ember exposure testing.

As part of its wildfire investigation, IBHS has partnered with the USDA Forest Service and the Savannah River National Laboratory (SRNL). IBHS scientists and engineers, in collaboration with forest service scientists and SRNL scientists and engineers developed the capability of

injecting burning embers into the wind stream in the large test chamber, effectively reproducing ember storms typically observed during wildfires. The ember generating equipment is shown in Figure 1. Five metal chambers were placed below grade in the five-foot wide pit. Five fans were also located in the pit. Large and medium bark mulch and wood dowels were used as the combustible material to generate embers. After ignition by a gas burner at the bottom of the chamber, a fan pushed the burning bark and dowel embers up through vertical ducts and into the wind field of the wind tunnel. One of the below grade chambers, filled with the bark mulch and wood dowel raw material, is shown in Figure 2. A building was designed and built for the ember exposure studies (page 13).

Ember Testing

Figure 1 (above). The IBHS ember generating equipment consists of five metal chambers, uniformly spaced across the test chamber, and located below grade in a five-foot wide pit. Each chamber was loaded with approximately 40 pounds of combustible bark mulch and wooden dowels. A propane gas burner located at the bottom of each chamber ignited the bark mulch and wooden dowel mixture, while a fan pushed the burning embers up through the vertical ducts and into the wind stream of the wind tunnel.


Figure 2. Bark mulch and wood dowels were used as the raw material mixture. Once ignited by a propane line burner located at the bottom of each chamber, a fan pushed the burning embers up through one of the three vertical ducts at the top of the chamber.


THE COMPONENTS INCLUDED:

1. DORMERDebris was placed at the intersection of the roof covering and the dormer walls, the same location where embers can accumulate and ignite this debris and expose the siding to a direct flame contact.

2. DIFFERENT ROOF COVERINGS Class A asphalt composition shingles, clay barrel tiles, and untreated wood shakes were used. The clay tiles are on a roof slope at the back of the test building that is similar to the one [being] covered by untreated wood shakes at the front of the building.

3. ROOF VALLEY Debris was placed there to represent the accumulation of flammable material along the valley, ignited by embers and to demonstrate the fire resistance of Class A shingles.

4. GUTTERS Debris was placed there and subsequently ignited by embers. This demonstrated the performance of vinyl and metal gutters.. The vulnerability of under eave vents to embers was also demonstrated.

5. WINDOW SCREENING Used to demonstrate whether or not screens can effectively reduce the entry of embers into the occupied space of a building. This series of tests also demonstrated the ease with which plastic-clad fiberglass screens can be damaged by a direct flame exposure.

6. MULCH When located at the base of the exterior walls, mulch can ignite, providing a direct flame contact exposure to the wall and other wall components.

7. RE-ENTRANT (INTERIOR) CORNER Seen here on the left side of the test building, this area can be particularly vulnerable to ignition and rapid flame vertical spread when mulch, landscaping vegetation and combustible siding are included in this area.

8. GABLE END VENT Vents can allow embers smaller than the mesh or large embers that burned down to the size of the mesh to enter the attic.

Debris next to dormer

Asphalt Shingles

Gable End Vent

2

4

1

Gutters

Untreated Wood Shake

2

5

8

3

7

8

6

Figure 3. An overview photograph of the test building. During a series of tests IBHS was able to investigate and demonstrate vulnerabilities of different components on the building. The building was rotated for different tests to expose the various roof covers and features to wind-driven embers.


Figure 4 shows the results of ember-started fires in the field of the roof (i.e., away from the roof edge or roof to wall intersection). The untreated wood shake ignited as a result of the ember exposure. These ignitions were localized and the fires, as seen here, were initially small. The fires burned through the shakes and the underlying roof sheathing, and would have entered the attic. The roof

fires were extinguished early, but if left unchecked, would have spread over the roof surface and into the attic. After this experience, the roof deck was covered with cement board and re-roofed with wood shakes as shown on page 13. The embers ignited the pine needle debris in the roof valley of the asphalt composition shingle roof (Figure 5). The shingles in this valley used a woven installation technique. Although the roof cover was damaged by the burning pine needles, the Class A shingles were not threatened and the fire did not burn through the roof cover into the attic.

As observed in Figure 6, a Class A roof covering can withstand the flame

contact exposure if accumulated debris is ignited. The adjacent siding and sheathing in the dormer construction must provide similar protection, or they will become the vulnerable components. It is best to keep accumulated debris to a minimum, but if present and ignited,

the vulnerability of the roof won’t be the Class A roof covering, it will be the components used to construct the dormer. In this example, fiber cement siding was used as the siding material.

Based on IBHS studies to date, vents that were more vulnerable to the entry of embers were those whose wide face was perpendicular to the wind flow carrying the embers. Examples of these vents were the gable end vent shown here (Figure 7) and the under eave vents in the blocking of open-eave construction (sometimes called frieze block vents). Ember entry into the attic through vents in soffited (boxed-in) eaves was minimal, and most of the ember entry observed for the boxed-in eaves resulted from embers entering through the gap between the fascia and roof sheathing (Figure 8).

Embers easily ignited the pine needle debris in the gutters and both pine needle and bark mulch placed at the base of the wall. Both vinyl and metal gutters were used. In Figure 9, the gutter on the left was vinyl and that on the right was metal. Once debris in the vinyl gutter ignited, it quickly detached from the fascia and fell to the ground. The burning debris contributed to the fire that resulted from the ignited mulch. When vinyl siding was used, the direct flame contact from the burning mulch and gutter debris caused the siding to deform and fall away from the wall, exposing the underlying sheathing. Flames from ignited debris and near-building vegetation resulted in a flame contact exposure to the window screen (Figure 10), allowing both flames and embers to enter the building. Entering flames and embers can easily ignite curtains and other furnishings. Ignition of the near-building mulch, and the damage from the resulting flame exposure, reinforces the importance of maintaining a low-combustibility zone near the home or building.

The metal gutter stayed in place, providing a flame contact exposure to the edge of roof. The vulnerability to the roof is at the edge – the fascia and roof sheathing. As seen in Figure 8, without effective flashing at the roof edge, this exposure could also result in additional entry of embers at the gap between the top of the fascia-to-roof sheathing.

Figure 7. A view from inside the attic, showing an ac-cumulation of embers (no longer burning), lodged in the screening of the gable end vent.

Figure 8. The burned-out embers shown on the top surface of this soffit material entered through the gap between the top the fascia and edge of the roof sheathing. These embers could have been generated either by the mechanical ember generators or the burning debris in the gutter. Ember accumulation in this area when metal angle flashing was used to cover this gap was minimal.

Figure 4. Ember ignitions on the untreated wood shake roof.

Figure 5. Post-test photo of the Class A fire rated as-phalt composition (fiberglass) roof covering, after the pine needles were ignited by embers and burned.

Figure 6. This dormer is typical of a vulnerability to embers that occurs on a “complex” roof, specifically at roof-to-siding intersections. Pine needles or other combustible debris can accumulate at these roof-to-siding intersections. If ignited by embers, the resulting fire will impinge on the siding.


SUMMARY OF FINDINGSThis series of ember experiments clearly showed the potential for embers to ignite vegetative debris that can either accumulate on the roof, in a gutter, or at the base of a wall, and combustible mulch products that can be placed adjacent to the home or business. Ignition of these combustible materials will result in a flame contact exposure to adjacent materials, including siding, windows, materials at the edge of the roof, and even near-by vegetation.

Although additional experiments are needed, these experiments also started to clarify the types and locations of openings that are vulnerable to the entry of embers.

Figure 9. Embers ignited debris in the gutters and mulch and vegetation at the base of the wall. Note also embers on the window screen. As long as the screen was intact, large embers were prevented from entering the interior of the building.

Figure 10. The window screen failed as a result of the flame contact exposure from ignited mulch and vegetation.

Figure 11. The mulch and vegetation in the re-entrant (interior) corner was ignited by embers, and subse-quently ignited the combustible siding. Flames quickly spread up the wall, impinging on the soffit. The aluminum soffit vent melted and flames were begin-ning to enter the enclosed eave above the soffit when the fire was extinguished. The rapid upward spread of flames was likely exacerbated by the vortex that was created in the interior corner and the close proximity of the combustible surfaces in the corner. Creating a non- or low-combustibility (e.g., irrigated lawn, use of non-woody, herbaceous, plants) in this area is critical. Use of noncombustible siding in this area may also be prudent.


Hurricane Demonstration Testing:IBHS RESEARCH CENTER REPORT:

The Insurance Institute for Business & Home Safety (IBHS) Research Center 2011 hurricane season demonstration test offered an opportunity to gain insight into roof and ventilation system wind-driven water entry issues.

Insights on Wind-driven Water Entry

By Timothy A .Reinhold, Ph.D., P.E.; Stephen Quarles, Ph.D.; Anne Cope Ph.D., P.E.; Tanya Brown Ph.D., and Zhuzhao Liu, Ph.D.


This unique, full-scale study of how wind-driven water penetrates openings in residential roof systems was modeled on real world, post-event damage assessments in areas where hurricane winds were strong enough to rip off roof cover, but not strong enough to blow off roof sheathing. In such instances, significant property damage and extended occupant displacement routinely occur due to water intrusion. In addition to wind-driven water pouring in – or being blown through – cracks between roof sheathing elements when primary roof cover is damaged and the underlayment is lost, water intrusion through residential roofs can originate from attic ventilation elements (e.g., ridge vents, gable end vents, and soffit vents).

Such damage is particularly common in inland areas, where hurricane-strength winds occur, but building codes and standards are not as stringent as in coastal jurisdictions. For example, when 2005’s Hurricane Wilma crossed the southern tip of Florida as a Category 2 hurricane with peak wind speed gusts of about 110 mph, she caused more than $10 billion of damage, most of which related to roof damage and resulting water intrusion. Much of this damage occurred far inland. Other hurricanes have caused catastrophic damage as they moved well inland. For example, after Hurricane Ike made landfall in Texas, it remained strong for two days, creating Category 1 hurricane force winds as far away as Ohio (and causing more than $1.5 billion of losses there).

Water penetration can cause extensive damage to interior finishes, furnishings and other contents, and can lead to ceiling collapse when insulation is saturated. Also, where power is lost and/or a house cannot otherwise be quickly dried out, mold growth is common. IBHS believes that the tremendous human and financial costs associated with water penetration during hurricanes could be substantially reduced through widespread adoption of relatively simple, inexpensive changes to residential roofing systems, such as sealing the roof deck (which only costs about $500 for an average-sized home).

Objectives for IBHS’ first wind-driven water research program included:

• quantifying the relative volume of water penetration through different roof openings;

• cataloguing types of water penetration damage to different parts of a house;

• demonstrating effective individual damage mitigation techniques, such as sealing the roof deck; and,

• illustrating why sealed roof decks are core components of the IBHS FORTIFIED for Existing Homes™ and FORTIFIED for Safer Living® program requirements for hurricane-prone regions.

The building specimen designed and constructed for the demonstration was a duplex, where sheathing joints on one half of the roof deck were sealed prior to installing roofing materials and the other half was not sealed. Both halves of the roof were then covered with simple felt paper underlayment prior to installing the asphalt shingles. The building included gable ends fitted with gable end vents and one foot wide soffits at the eaves. The roof sheathing stopped short along the primary ridge so it was possible to install a ridge vent during one set of tests.

All of these features have been addressed in the IBHS FORTIFIED Existing Homes™ bronze designation, which incorporates current best practices in a systems based approach to reducing water entry related losses in high wind events. These recommendations are also incorporated in the IBHS Roofing the Right Way guide.

The basic recommendations in the IBHS FORTIFIED Existing Homes ™ bronze brochure and the IBHS Roofing the Right Way guide related to preventing or reducing wind-driven water entry include:

1. Sealing the roof deck (joints or the entire surface) to prevent water from running into the attic through the gaps between the roof sheathing panels.

2. Ensuring that soffit panels (the flat panels installed between the bottom of the eaves at the roof edge and the wall of the house) are well attached to the house so they do not blow off in high winds, thereby creating an opening through which wind-driven water could enter the attic.

3. Covering gable end vents with flat shutter panels (plywood or some other flat material) when a hurricane threatens, to keep water from being blown into the attic.

Figure 1 Test duplex moving into the large test chamber at the IBHS Research Center.


4. Ensuring that ridge vents are products that have been tested and approved for resisting wind driven water entry and that they are adequately attached using the manufacturer’s recommendations for high wind installations.

The 2011 hurricane demonstration test gave IBHS its first opportunity to illustrate the relative success and importance of taking these steps to reduce the potential for water entry using high-definition photos and videos of the consequences of water entry into attic spaces during the demonstration testing. Quantitative measurements of water entry were obtained by researchers opportunistically during this demonstration testing to provide preliminary measurements and insight into the quantity of water entering into an attic through vents and between sheathing joints.

ESTABLISHING WIND-DRIVEN RAIN CAPABILITIESPlanning and research leading to the development of wind-driven rain capabilities at the IBHS Research Center have been ongoing for several years. IBHS provided support to the University of Florida (UF) to assist with deployment of a research disdrometer (an instrument that quantifies droplet size and rain fall rates, shown in Figure 2) in Hurricane Ike.

IBHS followed up with partial support for a Ph.D. student to analyze rain droplet size distribution based on Hurricane

Ike data, and then to use the UF wind simulator to select a commercially available spray nozzle to produce a similar distribution of rain droplet sizes in the IBHS Research Center test chamber. Thus, a realistic distribution of droplet sizes is required to achieve the same wetting patterns on buildings that occur during real world storms.

Figure 2–Precipitation Imaging Probe (PIP) style disdrometer mounted on Florida Coastal Monitoring Program (FCMP) portable weather station for Hur-ricane Ike data collection by University of Florida.

This summer, the student brought the research disdrometer to the IBHS lab to conduct tests of the completed system. The validation tests demonstrated that target rain deposition rates (8 inches per hour in American Society of Testing and

Materials and Florida Building Code test standards) and droplet size distributions were properly reproduced. NOTE: A Ph.D. dissertation is being written on this research and should be completed by the end of 2011.

MEASURING WATER ENTRY RATES

When the duplex was completed, including installation of wall board and ceiling drywall, drainage panels and tracks (DrySpaceTM) were installed to create water collection channels between the ceiling trusses, as shown in Figure 3. These channels were outfitted with drains and pipes that allowed collected water to be captured in plastic containers arranged throughout the interior (non-attic) space in the two halves of the duplex. The drainage system was installed in a modular system that allowed the collection of water in ceiling areas roughly 10 feet long by 2 feet wide. The trusses ran from front to back of the house and the 22½ inch space between the trusses was divided into three sections, each about 10 feet long. Each drainage channel directed water to a separate numbered plastic

container. Typical drain and collection locations are shown in Figure 4, Figure 5, and Figure 6 (opposite page). Tests were typically conducted for a 20-minute period, during which a constant wind speed was maintained and rainfall rate was set to produce 8 inches per hour on the test building (i.e., horizontally driven rain). At the completion of each test, water in the


buckets was measured and quantity was recorded.

QUANTITATIVE TEST PROGRAM SUMMARYA series of quantitative tests was conducted during the time available before the scheduled hurricane demonstration. The first test sequence involved measuring water entry rates when the soffit cover was missing along the entire length of the back eave of the duplex. The opening of approximately 8.5 sq. ft. under the eave of the roof where wind and wind-driven rain could enter the attic caused by the missing soffit is typical of the observed loss of the soffit cover in strong winds. Tests were conducted for wind speeds of 30 mph, 50 mph and 70 mph, during which the wall with the open soffit faced the wind flow, as shown in Figure 7. A quartering wind test (i.e., the wall with the open soffit was oriented at 45 degrees off perpendicular to the wind direction) was also conducted with a 50 mph wind speed.

The second test sequence involved repeating soffit tests with a typical perforated vinyl soffit panel intact, thus quantifying differences in water entry for typical soffits that remain undamaged vs. soffit material blown off during an event. For this round of quantification, tests were conducted at 50 mph and 70 mph with the wall with the soffit facing the wind, and at 50 mph for the quartering wind case.

The third test sequence focused on measuring water entry through the gable end vent. These tests were conducted with 30 mph and 50 mph wind-driven rain beating directly against the gable end. During these tests, soffits were covered with typical perforated vinyl soffit panel material.

Following the soffit and gable end quantification test series, roof cover on the front of the duplex was blown off using high winds. Similar efforts were started for the roof surface at the back of the duplex, when a fan drive fault ended wind generation for that day. Because of schedule constraints, it was decided to remove roof cover from the back roof surface to expose the sealed and unsealed roof decks above the same

eave where soffit water entry testing was conducted. Removal of roof cover from the front and back surfaces exposed the gap at the top of the primary ridge, so it was fitted with a Florida Building Code High Velocity Hurricane Zone approved ridge vent.

The final sequence of quantification testing included wind speeds of 50 mph with the back of the duplex facing the wind flow. This configuration put the exposed sealed and unsealed roof decks, shown in Figure 8, perpendicular to the wind-driven rain to allow a relative comparison in the amount of water entry in the attic for each half of the roof.

SUMMARY OF QUANTITATIVE TEST RESULTSOpen Soffit Tests (simulating loss of soffit material during a high-wind event):

1. A wind speed of 30 mph produced a light sprinkling of drops on the water collection drainage pans within 8 feet of the open soffit. However, no water actually trickled down the drainage system to collection buckets.

2. A wind speed of 50 mph produced an overall water entry rate into the attic of about 1.3 inches per hour based on the open area of the soffit. This is about 15% of the rainfall deposited on the adjacent wall surface (8 inches per hour). Most water was within the first 10 feet of the attic space adjacent to the open soffit.

3. A wind speed of 70 mph produced an overall water entry rate into the attic of about 2.9 inches per hour based on the open area of the soffit. This is a little more than 33% of the deposition rate on the adjacent wall surface.

4. A quartering wind of 50 mph produced an uneven distribution of water in the attic, but still resulted in about 1.6 inches per hour based on the open area of the soffit. This is about 20% of the deposition rate on a wall surface that would have been facing the wind flow.

COVERED SOFFIT TESTS (WHERE SOFFIT MATERIAL REMAINS IN PLACE):A wind speed of 50 mph resulted in water accumulation in the attic space of approximately 6% of the amount of water that entered during the same test for the open soffit case.

A wind of 70 mph produced about 9 times more water accumulation in the attic than the 50 mph test. This was

Figure 3–Photograph of water collection channels between ceiling trusses in duplex.

Figure 4–Photograph of water collection drains to collection buckets in the duplex.




about 25% of the amount of water that entered the attic during the same test (70 mph) for the open soffit case.

A quartering wind of 50 mph produced very little accumulation of water in the attic. The amount was about 2.5% of the water entering during the same test for the open soffit case.

GABLE END VENT TESTS:For winds of 30 mph and above, the water entry rate was about equal to the wind driven water deposition rate based on the area of the gable end vent. There was a slight indication of less water entry for higher wind speeds, but that likely was due to missed water that was blown farther into the attic and collected in the area around the access stairs where no collection pans were in place.

EXPOSED ROOF SHEATHING TESTS:The sealed roof deck side (where joints between the roof sheathing were sealed by applying a self adhesive modified bitumen tape) experienced about one-third of the water entry experienced by the side without tape. The amount of water entry through the roof deck was unprecedented in relation to tests conducted for soffit and gable end vents. The roof deck test actually had to be stopped at 16 minutes in duration, because the 3-gallon containers collecting water from each 10 foot by 2

foot collection area were overflowing. Some water entry on the sealed roof side was due to cuts in the tape that occurred when roof cover was removed. Even holes left by nails that pulled out when roof cover was removed led to steady drips of water into the attic. On the side where roof cover was blown off (shown in Figure 8), nails tended to stay in place, which would have reduced nail hole drips. Use of ring shank nails to fasten shingles and underlayment would likely help reduce these leaks, because they will be less likely to pull out, even if roof shingles are blown off. There was no sign of leaks through the Florida Building Code High Velocity Hurricane Zone approved ridge vent.

CONSEQUENCES OF WATER ENTRYFollowing quantitative testing, water collection devices were removed from the structure and the required drainage holes in the ceiling were patched. Furniture was placed in the duplex to model actual living spaces. The finished structure was then subjected to a series of wind-driven rain events modeled after Hurricane Dolly. These tests gave IBHS the opportunity to illustrate the consequences of water entry into attic spaces with compelling photos and video. Figure 9 is a photograph taken on the unsealed roof deck side of the duplex during the demonstration testing, while Figure 10 shows a similar view on the sealed roof deck side.

Figure 7–Photographs of the water entry quantifi-cation testing for the open soffit case with the wall facing the wind flow (top); close-up of the open soffit area (bottom).

Figure 8–Photograph of the front of the duplex after shingle and underlayment removal using high winds, il-lustrating the sealed roof deck (on the left) and the un-sealed roof deck (on the right).

Sealed Unsealed


The amount of water streaming into the living space during the demonstration in the unsealed roof deck side of the duplex, and the level of damage ultimately experienced on this half of the duplex, is typical of the level of water entry reported during real-world events. Within 45 minutes of the conclusion of testing, the kitchen ceiling in the unsealed side of the duplex collapsed, as shown in Figure 11 and Figure 12. Shortly thereafter, the living room area ceiling also collapsed, as shown in Figure 13.

Following the test, IBHS brought in an experienced property insurance claims adjuster to estimate the amount of damage each side of the duplex suffered. He assessed damage to the front three rooms on both sides of the duplex, including the kitchen, dining room, and family room. During a hurricane or high wind event, winds generally come from a relatively small range of directions after roof cover blows off, so damage confined to one area of a house would be typical of most people’s experience. The difference between estimated repair costs on the two sides of the duplex was substantial. The loss estimate for the side without a sealed roof deck is more than three times the loss estimate for the side with the sealed roof deck. Of particular note: the furniture in the side without a sealed roof deck required replacement, while furnishings in the side with the sealed roof deck only required cleaning.

CONCLUSIONS AND RECOMMENDATIONSThese preliminary tests clearly demonstrate that the areas addressed in the IBHS FORTIFIED Existing Homes™ and Roofing the Right Way guidance are important to reducing water entry in hurricanes and other storms where wind-driven rain is a factor. Clearly, sealing the roof deck is one of the most important protective measures that can be undertaken. However, the installer should be careful to make sure that seams are securely sealed and that the drip edge is attached using typical high-wind requirements for fasteners. It is likely that the High Velocity Hurricane Zone requirements for applying roofing cement around edges of the roof would also help reduce water entry if roof cover does suffer damage in a storm.

As a preliminary study, this work suggests that much more investigation is needed to quantify the amount of water entry that can be expected for normal construction, how much water entry is likely to be reduced with various water entry prevention measures, and how much water entry can be tolerated before costs of water entry remediation increase significantly.

Figure 9 –Photograph of the water entry during the demonstration event on the unsealed roof deck side of the duplex: close up of the recessed lighting in the kitchen.

Figure 10–Photograph of the kitchen during the demonstration event on the sealed roof deck side of the duplex.

Figure 11–Photograph of collapsed ceiling in the kitchen on the unsealed roof deck side of the duplex.

Figure 12–Photograph of fallen portions of collapsed ceiling in the kitchen on the unsealed roof deck side of the duplex.

Figure 13–Photograph of fallen portions of collapsed ceiling in the living room on the unsealed roof deck side of the duplex.


proposals for the International Green Construction Code (IGCC) for new and existing commercial buildings, as well as for international standards.

SYNERGIES BETWEEN RESIDENTIAL AND COMMERCIAL TESTINGWhile some IBHS Research Center testing will be unique to commercial structures, commercial risk managers also can learn from testing being done on residential specimens, since many small businesses (e.g., medical offices, salons, restaurants, shops) are located in residential-type buildings. For example, roof shingle testing is applicable to any building with a steep-sloped roof with shingles, as are commonly seen on Main Streets across America. Similarly, business owners will benefit from practical mitigation guidance resulting from Research Center tests and demonstrations that may be conducted on residential specimens. For example, the importance of keeping vegetation and other potential fuel sources away from buildings that face wildfire risk is applicable to both homes and businesses in communities with wildfire risk.

TRANSLATING RESEARCH INTO RISK REDUCTIONSome tests at the IBHS Research Center may take several hours to conduct, but the dramatic climax may occur in an instant. To properly record, review, and analyze building component and system performance throughout the test program, IBHS uses an array of wind instruments, hundreds of pressure sensors and dozens of load and displacement sensors. In addition, high-

definition digital cameras and stadium-style, broadcast-quality lighting captures building performance through powerful images and dramatic video. These permanent recordings of fleeting events are useful not only for researchers, but also for loss control professionals who work directly with policyholders to put effective risk management strategies in place.

In addition to their loss control and risk management peers, claims professionals can benefit from studying damage patterns and debris arising from IBHS Research Center initiatives. These pieces of physical evidence will assist such professionals as they work with commercial policyholders to repair or rebuild in a cost-effective manner that incorporates greater disaster resistance.

In addition, findings from the Research Center will strengthen IBHS’ other business protection programs, including FORTIFIED for Safer Business™ (a code-plus program to help businesses build light commercial facilities that are able to weather natural hazards and man-made risks); Open for Business® (a continuity planning tool to help business owners resume critical operations following a property loss or temporary shutdown); and Commercial Maintenance (practical advice for protecting buildings and contents against regional and seasonal risks). Together, these programs address all aspects of the property protection chain that is vital to all businesses. Learn more about FORTIFIED for Safer Business™ at www.DisasterSafety.org/fortified.

Continued from page 5

IBHS Research Center Will Strengthen Businesses Across America

data to complete its analysis. The final findings will be released in a report by RICOWI within the next six to 12 months.

CLAIMS ANALYSISIn addition to the field research conducted for the DFW hailstorm, IBHS is partnering with members Verisk and Xactware to complete a claims analysis of the event. Several IBHS member insurance companies are providing both their exposure and claims data from selected communities in the DFW area to Xactware. IBHS has selected communities based on damage seen during the field research, radar-based estimations of hail sizes, and the presence of large numbers of impact-rated roofs, among other criteria. IBHS researchers are outlining ways to query the data provided by its member companies, so that Xactware can complete statistical analyses and provide results of aggregated data to IBHS for study. IBHS is interested in learning how impact-rated roofs compare to non-rated products of the same age in terms of claim frequency and severity. Information on risk and performance will also be studied by comparing various types of products, ages of products, and configuration, among others. A secondary goal is to evaluate the accuracy of radar-estimated hail sizes, by comparing the severity of claims data to radar data. Radar technology has difficulty in distinguishing a large number of small hailstones from a small number of large hailstones, among other problems, and the accuracy of automated radar hail detection algorithms is questionable. Many members rely on radar-based estimates of hail fall, and an evaluation of the quality of these data would allow IBHS to provide better guidance in using them.

For more information about IBHS hail resources, visit the Hail Section of www.disastersafety.org.

REFERENCES[1] National Weather Service (January 2010), “Why One Inch Hail Criterion?” <http://www.weather.gov/oneinchhail/> (accessed December 1, 2010).


Hail


were instrumented with heat flux sensors that measured the radiant heat from the fires that were intentionally set at the edge of the burn plots.

The resulting crown fires moved past the wall assemblies and the heat flux was measured and recorded as a function of time. These results clearly showed that the measured heat flux at wall assemblies within 30 feet of a crown fire could reach and exceed 35 kW/m2; however this level was maintained for at most one minute since the fire was moving so rapidly.

Since IBHS results, and others, show that it takes minutes for most combustible products to ignite and for glass in windows to break, much less ignite curtains inside the home or business, at this exposure level, is building exposure to radiant heat really a problem? If you follow recommended vegetation management practices and develop and maintain defensible space zones, this level of radiant exposure is not very likely. When vegetation burns, it is typically a quick process, so whereas it may burn intensely, it will be for a relatively short period. Burning vegetation presents much more of a problem when it is close enough for the flames to actually touch the building or an attachment to the building, such as a deck. The intent of the defensible space requirements is to significantly reduce the opportunity for the flames from a wildfire to reach your home or business.

A scenario that can result in an elevated radiant exposure to a home or business, for an extended period of time, would be the ignition of a nearby building. This could be a detached garage or outbuilding, or a neighbor’s house. Buildings are stationary – if they ignite, they burn in place. Figure 6 provides an example of this. In this case, a neighboring home located about 40 feet from this home ignited during a recent wildfire in southern California and burned to the ground. Before the fire, this wall consisted of a dual pane window (annealed glass) and

vinyl siding that had been installed over an existing solid wood siding product. Vegetation between the two homes consisted mostly of larger, well pruned, pine trees. Most of the “wildfire” exposure to this home was the radiant heat from the burning neighbor’s home. In this figure, you can see remnants of the remaining vinyl siding (most has already detached and is on the ground). You can also see that the outer pane of the dual pane window has broken. The inner pane is still in place. This house has suffered considerable damage, but it wasn’t destroyed.

The recent radiant panel experiments at the IBHS Research Center has provided needed visuals for educational materials, and has helped to clarify the relative importance of radiant heat exposure to external building components.

REFERENCESCohen, Jack D. 2004. Relating Flame Radiation to Home Ignition Using Modeling and Experimental Crown Fires. Canadian Journal of Forest Resources 34:1616-1626.


Radiant Panel

Figure 6

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Insurance CompanyFarm Bureau Town and Country Ins. Co. of MOFarmers Alliance CompaniesFarmers Home GroupFarmers Insurance GroupFarmers Mutual Insurance CompanyFarmers Union Mutual Insurance CompanyFederated Mutual Insurance

Fidelity National Property and CasualtyInsurance Group

Fireman’s Fund Insurance CompanyFirst Home Insurance CompanyFirst Nonprofit Insurance CompanyFlorida Farm Bureau Insurance GroupFlorida Farm Bureau CasualtyFM GlobalFrankenmuth Mutual Insurance CompanyGeneral Re CorporationGeorgia Farm Bureau Mutual

Insurance CompanyGeoVera Insurance Glencoe GroupGrange Insurance

(The Grange Mutual Casualty Group)Grange Insurance AssociationHanover Insurance CompanyHarbor Point Re LimitedHingham Mutual Fire Insurance CompanyHomesite Insurance GroupHomeWise Insurance CompanyICW GroupIndiana Lumbermens Mutual

Insurance CompanyInterinsurance Exchange of the Automobile ClubIsland Insurance Company, Ltd.Kemper, A Unitrin BusinessKentucky Farm Bureau Insurance Lantana Insurance Ltd.Liberty Mutual GroupLloyd’sLoudoun Mutual Insurance CompanyLouisiana Farm Bureau Mutual

Insurance CompanyMain Street America GroupMax Re Capital Ltd.Merastar Insurance CompanyMetLife Auto & Home MiddleOakMillers Capital Insurance CompanyMississippi Farm Bureau Casualty

Insurance CompanyMotor Club Insurance Association of NebraskaMotorists Insurance GroupMunich Reinsurance America, Inc.Mutual Assurance Society of VirginiaNationwide InsuranceNew England Mutual Insurance CompanyNew Jersey Manufacturers Insurance CompanyNorfolk & Dedham GroupNorth Carolina Farm Bureau Insurance Group

Ohio Mutual Insurance GroupOklahoma Farm Bureau OneBeacon Insurance CompanyPacific Select Property Insurance CompanyPartner Reinsurance Company of the U.S.Patrons Mutual Insurance Company of CTPenn Millers Insurance CompanyPennsylvania Lumbermens Mutual

Insurance CompanyPhenix Mutual Fire Insurance CompanyPMA Insurance GroupProperty Insurance Plans Service Office, Inc

(PIPSO)Providence Mutual Fire Insurance CompanyPURE High Net Worth InsuranceQBE Specialty InsuranceQuincy Mutual Fire Insurance CompanyRenaissanceRe Holdings Ltd.Rockingham GroupRural Community Insurance CompanySafety Insurance CompanySafeway Property Insurance CompanySECURA Insurance CompaniesSecurity First Insurance CompanySelective Insurance Group, Inc.Service Insurance CompanySompo Japan Insurance Company of AmericaSouth Carolina Farm Bureau Mutual

Insurance CompanySouthern Farm Bureau Casualty

Insurance CompanySouthern Mutual Church Insurance CompanyState Farm Fire and Casualty CompanyStonington Insurance CompanyStonington Lloyds Insurance CompanySunshine State Insurance CompanyTexas Farm Bureau Mutual Insurance GroupTokio Millennium Re Ltd.Tower Hill Insurance GroupTravelers Union Standard Insurance GroupUnited Property & Casualty Insurance CompanyUnitrin, Inc.Universal North AmericaUSAAUtica National Insurance GroupVermont Mutual Insurance CompanyVirginia Farm Bureau Western Iowa Mutual Insurance AssociationXL Re Ltd. Zephyr Insurance Company, Inc.

INSURANCE INSTITUTE FOR BUSINESS & HOME SAFETY MEMBER COMPANIES

The Insurance Institute for Business & Home Safety (IBHS) mission is to conduct objective, scientific research to identify and promote effective actions that strengthen homes, businesses, and communities against natural disasters and other causes of loss. Please visit our web site at www.DisasterSafety.org.

Insurance Institute for Business & Home Safety4775 East Fowler Ave.

Tampa, FL 33617(813) 286-3400

DisasterSafety.org

Disaster Safety Review 2011 - Vol. 1

Documents

Transcript of Disaster Safety Review 2011 - Vol. 1