PowerPoint Presentation
Severe Thunderstorm Impacts and MitigationHail MitigationTanya
M. Brown, Ph.D.Lead Research Engineer & Director of Hail
ResearchNHMA SymposiumJuly 23, 2015
Hailstorm Risks
Severe hail (1+ in. diameter) most commonly occurs in
thunderstormsLargest hailstones occur in supercell thunderstorms
with strong updraftstornadoes can be presentRisk extends across
country in areas east of Rocky MountainsMore than 75% of cities in
U.S. experience at least one hailstorm/yearOn average, annual hail
losses ~$1B
May 24, 2011 DFW Claims StudyHailstorms caused $875M+ in insured
lossesClaims study comparing:Roofing material
performanceAgingRelative difference in roofing damage vs.
walls/windows/doors/trim damageRadar-estimated hail severity vs.
claim severityMore than 67,000 policies in forceMore than 6,600
claims
May 24, 2011 DFW Claims Study
May 24, 2011 DFW Claims Study
Asphalt Shingle Impact Resistance TestingSystematic approach to
compare:Different classes of materials3-tab vs. architectural
shinglesStandard vs. IR vs. premiumTraditional IR vs. polymer
modified IRStandards UL 2218 and FM 4473Altered test methods
different density and/or hardness of stonesAging and climate
effects
UL 2218 Asphalt Shingle ImpactTest Method & Observations
Asphalt Shingle Impact Resistance Testing
IR 3-tab products performed better than the basic 3-tab products
(about 55 to 225 percent better) for all steel ball impact classes.
The basic products had relatively consistent passing rates for the
Class 2 and larger steel ball impacts, while the IR products showed
consistent passing rates for Class 3 and larger steel ball
impacts.
Class 1 UL 2218 impacts resulted in passing ratings for about 65
percent of the impact locations on the IR 3-tab shingles versus
about 45 percent for the basic 3-tab shingles.Class 2 UL 2218
impacts resulted in passing ratings for about 75 percent of the
impact locations on the IR 3-tab shingles versus about 25 percent
for the basic 3-tab shingles.Class 3 UL 2218 impacts resulted in
passing ratings for about 60 percent of the impact locations on the
IR 3-tab shingles versus about 25 percent for the basic 3-tab
shingles.Class 4 UL 2218 impacts resulted in passing ratings for
about 60 percent of the impact locations on the IR 3-tab shingles
versus about 25 percent for the basic 3-tab shingles.
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Asphalt Shingle Impact Resistance Testing
Polymer modified IR shingles performed better than traditional
IR shingles (about 20 to 50 percent improvement) for all four steel
ball impact classes. This was most noticeable at the larger steel
ball sizes (1.50-2.00 in.) where the polymer modified shingles
performed at least 40 percent better than the traditional IR
shingles.
Class 1 UL 2218 impacts resulted in passing ratings for about 85
percent of the impact locations on the polymer modified IR products
compared to about 70 percent for the traditional IR shingles.Class
2 UL 2218 impacts resulted in passing ratings for about 90 percent
of the impact locations on the polymer modified IR products
compared to about 60 percent for the traditional IR shingles.Class
3 UL 2218 impacts resulted in passing ratings for about 75 percent
of the impact locations on the polymer modified IR products
compared to about 50 percent for the traditional IR shingles.Class
4 UL 2218 impacts resulted in passing ratings for about 55 percent
of the impact locations on the polymer modified IR products
compared to about 35 percent for the traditional IR shingles.
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Replicate IBHS ice balls like natural hailDevelop damage rating
scaleFocus on what can be seen from the surface applicability to
claims!!Explain relationship of different ratings for the remaining
life of the roof pilot cosmetic vs. functional damage studyFurther
exploration of preliminary finding hard and soft ice balls seem to
cause different visible damage signaturesFuture: Ice Ball Asphalt
Shingle Impact Tests
Future: Ice Ball Asphalt Shingle Impact Tests
Where Are We Going?
Where Are We Going?
Severe Storm Protection Systems
Gables, Porches, Carports and ChimneysGarage Doors and Structure
(CLP)Roof
High Wind & Hail
The National Standard for Resilient Construction
New and existing homes are eligible for designation
Be sure to mention that FORTIFIED Home standards for High Wind
and Hail are for both new and existing construction.144/27/2012
Systems-Based Approach vs. La CartePuts performance firstTreats
home as collection of systemsStrengthens most vulnerable
systems/features first
Consider for a moment the components that comprise the roof
system: Roof framing (type and spacing), roof decking material,
roof decking thickness, roof decking attachment (fastener type,
size and spacing), roof deck sealing method, roofing underlayment,
drip edge installation, finally roof covering.
Energy efficiency failures can lead to higher ownership cost,
resilience failures can lead costly and disruptive failures, and in
extreme circumstances violent and sudden catastrophic losses.
Text from slide: Without adequate resilience, risk of loss can
be significant even in low intensity events. Systems-based approach
used in FORTIFIED seeks to mitigate all of the components that make
up vulnerable assemblies. la carte approaches encourage the
selection of individual components to achieve a score/credit.
Score, first; Performance second.15
FORTIFIED Roof High Wind and Hail BronzeMinimum 7/16 in. OSB or
plywood roof deckRoof deck attachment = 2 options8d smooth or 10d
smooth nailsSpaced at 4 in. o.c.8d ring shank nailsSpaced 6 in.
o.c. Drip edge required with 3 in. laps and fastened at 12 in.
o.c.
Roof covering spec is critical-
Shingles are rated for wind speed, metal roofs must be rated and
attached for the wind design pressure.
Both must be installed per manufacturers requirements for the
appropriate wind speed/ design pressure
Tile must be installed to meet the required aerodynamic uplift
moment.
164/27/2012
FORTIFIED Roof High Wind and Hail BronzeRoof deck must be sealed
with a qualified systemTaped seams2-layers of #30 feltFully adhered
membraneReinforced synthetic underlayment installed for high wind
and prolonged exposureClosed-cell foam polyurethane adhesive
applied to the underside of deck (retrofit)Roof covering must be
high-wind rated, Class F or higher, and impact-rated, either Class
3 or 4 depending on roof covering type
Roof covering spec is critical-
Roof deck must be sealed with a qualified system- Entire roof
deck covered with full layer of self-adhering poly modified bitumen
membrane- Application of self-adhering polymer modified bitumen
flashing tape at horizontal and vertical joints in the roof deck-
Application of reinforced synthetic roof underlayment with an ICC
approval
174/27/2012
www.disastersafety.org
IBHS IS A STONG SUPPORTER OF MODERN, WELL-ENFORCED BUILDNG
CODES, BUT AWAY FROM THE COASTS, EVEN THE NEWEST CODES DO NOT
REALLY PROTECT HOMES AND COMMERCIAL STRUCTURES AGAINST HIGH
WINDS.
So, IBHS created a set of science-based, voluntary building
standards known collectively as FORTIFIED.
A FORTIFIED DESIGNATION IS AN INDIVIDUAL INDICATOR OF A
PROPERTYS RESILIENCE TO A PARTICULAR HAZARD.
Fortified is increasingly be used by our industry, as well as
builders at all price points.
Holistic, system-based approachThird-party inspections &
validation of required elements (design / construction)
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