A 1 2008 Wind Loss Mitigation Study 2008 Wind Loss Mitigation Study Florida Building Commission...

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2008 Wind Loss Mitigation Study2008 Wind Loss Mitigation Study

Florida Building CommissionFlorida Building CommissionHurricane Research Advisory CommitteeHurricane Research Advisory Committee

December 2008December 2008

L. A. Twisdale, Ph.D., P. E.

Applied Research Associates, Inc.

8537 Six Forks Road

Raleigh, N. C. 27615

919 582-3336

0.00

10.00

20.00

30.00

0.00 50.00 100.00 150.00A

Lo

ss /

A C

OV

Lim

it (%

)Peak gust wind speed in open terrain (mph)

Pre 2002

Post 2002

Loss Reduction

NewData

1. Lab/Full-Scale Test Data

4. Insurance Loss Data

3. FL Bldg Code Updates

2. Field Surveys

5. Hurricane Wind Climate Model

• Roof Pressure Coefficients

• Wall and Soffit Pressure Coefficients

• WBD Transport Tests

• WBD Impact Tests

• Terrain Velocity Profiles

• Glazing Impacts• Water Intrusion• Full-Scale House

Components IBHS/UF

• Florida Coastal Monitoring Program

Hurricanes• Charley• Ivan• Frances• Jeanne• Wilma

Data• Claims Level• Policy Level• By Coverages

Focus• Pre-FBC vs. Post-FBC• Mitigation Features• Non-Modeled Losses• Water Intrusion• Tree Fall• Attached Structures• Damage-to-Loss

• Coastal Code Plus

• Terrain Definitions

• No Partially Enclosed Designs

• Aluminum Structures

• Wind-Borne Debris Region

• Soffit Loads

• 2004/5 Hurricanes• UF• ARA• DCA

• IBHS Post-Charley Permit Analysis

• OIR Exterior Structure Survey• Single

Family• Mobile

Homes

Model Updates• Wind Shear• OceanMixing• Boundary Layer

Model• Holland B

parameter• Decay after Landfall• Additional

Storm/Windspeed Observations

• Validation Uncertainties

Office of Insurance Regulation

• Admin• Actuarial

Review• Contract

Update Damage and Loss Models

Multi-Family Loss RelativitiesSingle Family Loss Relativities

Final ReportDraft Final Report

Quantify Losses

• Locations• Buildings• Mitigation Features• AAL• Loss Costs• Relativities

Insurance Parameters

• Deductibles• Coverage Ratios• Coverage Exclusions

Model Buildings

• New Bldg Models• Simple Building

Plans• Actual Florida

Building• New Designs to FBC

Terrain

• Coastal• Open• Suburban• Treed Suburban

Sensitivity Analyses and Implementation

• Primary vs. Secondary Features• Statistical Analysis/Rank Order• Final Loss Relativities• Insurance Credits• Inspection/Verification

Location Points

• Current FBC Wind Zones

• Updated Wind Map

Technical Advisory

Committee

• Actuaries• Florida

Building Commission

• Builders• Engineers• Insurance

Companies

Validation with Damage and Insurance Loss Data

Methodology and Analysis

2

OutlineOutline

I. Objectives II. Methodology/New DataIII. Model Validation/Insurance LossesIV. Building Model Simulations of

Mitigation FeaturesV. Summary

I. ObjectivesI. Objectives

3

ObjectivesObjectives1. Update the 2002 Loss Relativity Studies for Single

Family and Multi-Family Residences

2. Incorporate new data and research since 2002 Hurricane damage/insurance loss data from 2004-5 hurricanes Wind tunnel test data Wind-borne debris and terrain modeling research Impact testing Exterior structure insurability project Water intrusion data and testing—as available New hurricane hazard modeling data Updates to Florida Building Code since 2002

3. Develop public domain report

4

5

Some Key Loss Relativity FeaturesSome Key Loss Relativity Features

Roof-to-Wall Connection

Roof Shapeand Bracing of

Gable End

Protection of Openings Doors

SecondaryWater Resistance

Roof Deck Attachment

Protection of Openings

Roof Covering

Building Envelope Performance is Critical to Controlling Losses

6

2002 Study Results2002 Study Results

Worst building has a loss cost 2.37 times the “representative” building

Best building has a loss cost of 0.41 times the “representative” building

II. Methodology/New DataII. Methodology/New Data

7

8

MethodologyMethodology Analyze individually-modeled

buildings Estimate loss costs Repeat for different

combinations of wind-resistive features

Wind resistive features must be practically verifiable

Evaluate locations throughout Florida

For each location, convert loss costs to loss relativities

Simplify results as needed

9

Modeling and Analysis ApproachModeling and Analysis Approach

New HurricaneHazard ModelNew Wind Tunnel

Data(wind loads, terrain effects)

FBC

NewInsurance LossData

New Post StormPhysical Damage Surveys

Updated Physical Damage And Loss Adjustment Models

Loss Costs and Rate Differentials

New Component Resistance Data

Mitigation Features

Updated Hurricane Wind RiskUpdated Hurricane Wind Risk

10

0

10

20

30

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

Location Point

Av

era

ge

Nu

mb

er

of

Hu

rric

an

es

p

er

10

0 Y

ea

rs

> 150 mph

120-150 mph

100-120 mph

< 100 mph

0

10

20

30

40

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

Location Point

Num

ber o

f Hur

rican

es

Greater Than

Less Than or Equal To

1. There are significant differences in old and new hurricane model and Florida wind maps.

2. SE Florida average hur winds (>50mph) every 5 years.3. Many Florida locations average more than 10 times as

many hurricanes below vs above the design winds.

11

New Wind Tunnel DataNew Wind Tunnel Data

12

Gable Roof Pressures vs. SlopeGable Roof Pressures vs. Slope

-3

-3

-3

-2.5

-2.5

-2.5

-2.5

-2.5

-2

-2

-2

-2

-2

-2

-1.5

-1.5

-1.5-1.5

-1.5

-1.5

-2.5

-2.5

-2.5

-2.5

-3

-3-3

Gable4:12-Suburban

-5

-4.5

-4

-3.5

-3

-2.5

-2

-1.5

-1

-0.5

0

-3

-2.5

-2

-2

-2

-2

-1.5

-1.5

-1.5

-1.5

-1.5

-1.5

-1.5

-1

-1-1

-1

-1

-1

-1

-1

-2

-2

-2

-2

Gable7:12-Suburban

-5

-4.5

-4

-3.5

-3

-2.5

-2

-1.5

-1

-0.5

0

-3-2.5

-2

-2

-1.5

-1.5

-1.5

-1.5

-1.5

-1.5

-1.5

-1

-1

-1

-1

-1

Gable9:12-Suburban

-5

-4.5

-4

-3.5

-3

-2.5

-2

-1.5

-1

-0.5

0

-3-2-2

-1.5

-1.5-1.5

-1.5

-1

-1

-1

-1

Gable12:12-Suburban

-5

-4.5

-4

-3.5

-3

-2.5

-2

-1.5

-1

-0.5

0

4:12

12:12

7:12

9:12

Note the reduced loads for steeper slopes.

13

New Component Resistance DataNew Component Resistance Data1. Residual Capacity of

Shutters2. Residual Capacity of

Laminate Glass Units3. Impact Capacity of

Unprotected Glazing for Shingles

4. Soffit Resistances

10987654321

99

95

90

80

70

605040

30

20

10

5

1

1/ 8" 2x2 inc speed

Perc

ent

Mean 5.527StDev 1.106N 12AD 0.215P-Value 0.802

Probability Plot of 1/ 8" 2x2 inc speedNormal - 95% CI

14

New Hurricane Survey DataNew Hurricane Survey Data

0%

2%

4%

6%

8%

10%

12%

14%

16%

18%

20%

Shingles Tiles

Ave

rag

e %

Dam

age

Per

Ho

use

Roof Cover Type

Average % Roof Cover Lost

Pre-FBC

Post-FBC

Roof Cover Type

0%

5%

10%

15%

20%

25%

Mortar Nail/Screw

Tile Attachment Method

Ave

rag

e %

Ro

of

Co

ver

Dam

aged

Tile Attachment

Hurricane Charley Damage Survey370 Houses in Charlotte Harbor Area

Post-FBC roof covers have 50% less damage

Mortar set tiles have 50% more damage

Roof Shape and Window ProtectionRoof Shape and Window Protection

15

0%

5%

10%

15%

20%

25%

30%

All Windows Unprotected All Windows Protected

Window Protection

% H

omes

With

At L

east

One

Dam

aged

W

indo

w

0%

5%

10%

15%

20%

25%

Gable Hip

Roof Shape

% R

oof C

over

Dam

age

Roof Shape

Window ProtectionGables 33% more roof cover damage

Unprotected windows experienced 5 times more damage.

Performance of Screen Performance of Screen Enclosures in Hurricane CharleyEnclosures in Hurricane Charley

16

0%

20%

40%

60%

80%

100%

Collapse PartialFrame

Damage

ScreenOnly

None

Failure/Damage Categories

Pe

rce

nta

ge

89% of Alum Frame Screen Enclosures collapsed or had partial frame damage.

OIR 2007 Exterior Structure Survey OIR 2007 Exterior Structure Survey

17

1. 765 Homes surveyed2. Average of 0.86 Exterior Structures per home3. Average replacement value was 10.3% of Coverage A,

but highly skewed distribution4. Based on a sample of claim reviews:

•Ext structures averaged 28% of the total claims for Wilma•Ext structures averaged 8% of the total claims in Charley

Percent of Surveyed Homes with Exterior Structures

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

PatioEnclosure

StorageShed

Garage OpenStructure

Sunroom Other Carport Deck

Exterior Structure Type

Pe

rce

nt

Site-Built SingleFamily Homes

ManufacturedHomes

Single Family Total Exterior Single Family Total Exterior Structure Claim LossesStructure Claim Losses

18

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

Deck Sunroom Carport Garage Other,Pool/spa

StorageShed

Fence Pool/PatioEncl

Type of Exterior Structure

Per

cen

t of H

om

es w

ith E

xter

ior

Str

uct

ure

Lo

sses

Wilma

Charley

Get a copy of the ARA Report “Evaluation and Report on the Insurability of Attached and Free Standing Structures,” May 2007 on the OIR website.

We analyzed Single Family claims for:•204 homes in Hurricane Charley•212 homes in Hurricane Wilma

III. Insurance Losses/Model III. Insurance Losses/Model ValidationValidation

Policy Level Data 7 Florida Hurricanes (2004-2005) 8 Insurance Companies 41 Total Data Sets Data included wind mitigation features

for subset of exposure

Claim Folder Level Data Review 1109 Claim Folders Reviewed

19

Policy Level Data Analysis ApproachPolicy Level Data Analysis Approach

20

1. Each building is located and the hurricane swath windspeed at that location is used as the independent variable.

2. Mean paid loss is computed by windspeed bin for each group of buildings with similar characteristics

3. Three analysis methods:• Loss vs Year Built.• Loss vs. Windspeed.

Produce empirical loss function by applying multipoint smoothing to average over randomness and sample size limitation.

• Average Annual Loss.

0 50 100 1500

10

20

30

Peak Gust Wind Speed in Open Terrain (mph)

Mea

n A

Los

s F

unct

ion

(%)

Hurricane Charley

0 50 100 1500

0.2

0.4

0.6

0.8


Mea

n A

Los

s F

unct

ion

(%)

Hurricane Frances

0 50 100 1500

0.5

1

1.5

2


Mea

n A

Los

s F

unct

ion

(%)

Hurricane Jeanne

0 50 100 1500

2

4

6


Mea

n A

Los

s F

unct

ion

(%)

Hurricane Ivan

0 50 100 1500

10

20

30


Mea

n B

Los

s F

unct

ion

(%)

Hurricane Charley

0 50 100 1500

1

2

3


Mea

n B

Los

s F

unct

ion

(%)

Hurricane Frances

0 50 100 1500

2

4

6


Mea

n B

Los

s F

unct

ion

(%)

Hurricane Jeanne

0 50 100 1500

10

20

30


Mea

n B

Los

s F

unct

ion

(%)

Hurricane Ivan

Raw Data Empirical Loss Functions after Smoothing

Loss vs. Windspeed

Hurricane Charley SwathHurricane Charley Swath

21

ASOS Description

Obs ModelKFMY Fort Myers International Airport 85 80KMCO Orlando International Airport 107 109KSFB Orlando Sanford International Airport 94 91KORL Orlando Executive International Airport 87 97KMIA Miami International Airport 41 34KMLB Melbourne Regional Airport 49 53KPBI Palm Beach International Airport 41 37KRSW SouthWest Florida International Airport 81 69FCMP T0 FCMP Tower T0 54 59FCMP T1 FCMP Tower T1 76 82FCMP T2 FCMP Tower T2 49 45FCMP T3 FCMP Tower T3 39 43SAUF1 St. Augustine C-MAN Station 71 65KOMN Ormond Beach Municipal Airport 80KPGD Charlotte County Airport 141

Peak Gust Speed(mph)

y = 0.99x

R2 = 0.93

0

20

40

60

80

100

120

0 20 40 60 80 100 120

Peak Gust Wind Speed (mph) - Observations

Pe

ak

Gu

st

Win

d S

pe

ed

(m

ph

) -

Mo

de

led

Post event modeling is based on:• Anemometer Data • Pressure Data • Track History• Translation Speed

Estimate Rmax , B for Wind ModelProduce windspeed and direction time histories at any pointSwath shows peak gust at each locationSwath is key to analyzing insurance losses, bldg performance

15 Anemometer Measurements

Hurricane Wilma SwathHurricane Wilma Swath

22

Station Description Peak Gust Wind Speed (mph)Observed Modeled

KMLB Melbourne International Airport 65 46KFMY Fort Myers Airport 81 69KFLL Fort Lauderdale Airport 106 113KPBI Palm Beach Airport 108 115KMIA Miami Airport 99 109KFPR St. Lucie County Airport 87 76T0 FCMP Tower 106 111T1 FCMP Tower 105 122T3 FCMP Tower 106 109T2 FCMP Tower 117 120FWFY1 Data Buoy 108 108S140W SFWMD Anemometer 108 113LXWS SFWMD Anemometer 113 118LZ40 SFWMD Anemometer 109 115S7WX SFWMD Anemometer 115 114STA5WX SFWMD Anemometer 101 102S331W SFWMD Anemometer 113 108BELLW SFWMD Anemometer 111 101L006 SFWMD Anemometer 112 123L001 SFWMD Anemometer 107 87SGGEWX SFWMD Anemometer 107 119ACRAWX SFWMD Anemometer 124 110VAKF1 C-MAN Station 99 113SFWMD - South Florida Water Management District

y = 1.009xR² = 0.692

0

20

40

60

80

100

120

140

0 20 40 60 80 100 120 140

Pea

k G

ust

Win

d S

pee

d (

mp

h)

-M

od

eled

Peak Gust Wind Speed (mph) - Observations

23 Anemometer Measurements

Mean Mean Loss Loss vs vs Year Year BuiltBuilt

23

0

5

10

15

20

25

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000

Year Built

Mea

n (

A L

oss

/ A C

ov.

Lim

it, %

)

All Wind Speeds

100-120 mph

80 - 100 mph

> 120 mph

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000

Year Built

Mea

n (

A L

oss

/ A C

ov.

Lim

it, %

)

All Wind Speeds

0

1

2

3

4

5

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000

Year Built

Mea

n (

A L

oss

/ A C

ov.

Lim

it, %

)

100-120 mph

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000

Year Built

Mea

n (

A L

oss

/ A C

ov.

Lim

it, %

)

80 - 100 mph

0

5

10

15

20

25

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000

Year Built

Mea

n (

A L

oss

/ A C

ov.

Lim

it, %

)

> 120 mph

>120 mph winds include some envelope failures.

There is a noticeable reduction in loss for recently built homes.

>2002

Pre- and Post-FBC ConstructionPre- and Post-FBC Construction

24

0.00

10.00

20.00

30.00

0.00 50.00 100.00 150.00

A L

oss /

A C

OV

Lim

it (%

)

Peak gust wind speed in open terrain (mph)

Pre 2002

Post 2002

0.00

10.00

20.00

30.00

40.00

50.00

0.00 50.00 100.00 150.00

A L

oss /

A C

OV

Lim

it (%


Pre 2002

Post 2002

1 Story Single Family 2 Story Single Family

Loss Reduction

One vs Two StoriesOne vs Two Stories

25

0.00

10.00

20.00

30.00

40.00

50.00

0.00 50.00 100.00 150.00

A L

oss /

A C

OV

Lim

it (%

)


1 Story

2 Story

0.00

5.00

10.00

15.00

0.00 50.00 100.00 150.00

A L

oss /

A C

OV

Lim

it (%

)


1 Story

2 Story

Pre FBC 2001 Post FBC 2001

Loss Reduction

Roof ShapeRoof Shape

26

0.00

10.00

20.00

30.00

40.00

50.00

0.00 50.00 100.00 150.00

A L

oss /

A C

OV

Lim

it (%

)


Gable

Hip

Gable vs Hip

0

2

4

6

8

0 50 100 150A

Los

s /

A C

OV

Lim

it (%


Hip

Gable

Company A Company F

This differences integrates to about a 20% increase in loss for gable vs hip.

Opening ProtectionOpening Protection

27

0

1

2

3

4

5

6

0 50 100 150

A L

oss

/ A

CO

V L

imit

(%)


No Opening Protection

Hurricane Opening Protection

Loss Reduction

““Weak” vs “Strong” HouseWeak” vs “Strong” House

28

0

1

2

3

4

5

0 50 100 150

A L

oss

/ A

CO

V L

imit

(%)


Weak-HouseStrong-House

Weak House• Two Story• Gable • Non-FBC Roof Cover• No Opening Protection

Strong House• One Story• Hip• FBC Roof Cover• Opening Protection

Loss Reduction

•Strong house group has a 65% loss reduction over weak house group, when extrapolated and integrated for a Tampa location. •This corresponds in a loss relativity of 1.0 to 0.35, which is in the range of modeled results.

29

Empirical Functions “track” Empirical Functions “track” Building Model Loss FunctionsBuilding Model Loss Functions

Unmitigated Older Code (say, pre-1990) House

Gable, wood frame, 6d deck nails, toe-nail roof to wall, no shutters

Re-nailed roof deck, Secondary Water Resistance, Roof straps added

Upgraded Roof

Curves move to right. Damage and loss are reduced the more the curves move to right.

Each curve is produced by simulating detailed engineering building model with specified construction features in a specific terrain.

Average Loss Reduction Using Average Loss Reduction Using Insurance Data Insurance Data vsvs Modeled Losses Modeled Losses

30

Integrate Loss Functions

Compare Differences in AAL considering presence and absence of wind mitigation feature

Analyze features or variable groups with sufficient data to compare differences in expected loss

0 0

)()()()(n

nv npndvvpvDLE

Insurance Claim Review DataInsurance Claim Review Data

31

Analyzed Claims for:

1. Repair and replacement costs given damage

2. Roof cover replacement triggers

3. R&R unit costs

4. Losses from non-breach of envelope

5. Exterior Accessories

6. Tree damage/removal

Fast Review Full Review Received

Single Family 231 218 231

Multi- Family 86 10 90Mobile Home 0 0 77







1142 758 1385

Wilma

Total Reviewed

Storm Type

Count of Claims

Charley

Frances

Ivan

Insurance Claim Review DataInsurance Claim Review Data

32

Analyzed Claims for:

1. Repair and replacement costs given damage

2. Roof cover replacement triggers

3. R&R unit costs

4. Losses from non-breach of envelope

5. Exterior Accessories

6. Tree damage/removal

-10%

0%

10%

20%

30%

40%

50%

60%

70%

0-70 70-80 80-90 90-100 100-110 110-120 120-150

Perc

ent o

f Dir

ect L

oss t

o Bu

ildin

g

Wind Speed Range (mph, open, gust)

Average Loss from Building Components

Soffits Interior Exterior Accessories

Roof Cover Fenestrations Roof Deck

0%

20%

40%

60%

80%

100%

120%

0-70 70-80 80-90 90-100 100-110 110-120 120-150

Perc

ent o

f Dir

ect L

oss t

o Bu

ildin

g

Wind Speed Range (mph, open, gust)

Average Loss from Non-Building Components

Attached Screen Enclosures Other Attached Structures Detached StructuresTree and Tree Debris Removal Debris & Temporary Repair

Roof Cover- 50% of direct loss

Screen Encl adds > 50% of direct loss

IV. Building Model Simulations IV. Building Model Simulations of Mitigation Featuresof Mitigation Features

33

Important Building FeaturesImportant Building Features

34

Single family and Group I Multi-family Groups II and III Multi-family

2002 Features Features Added in 2008 2002 Features Features Added in 2008

1. Terrain 2. Roof Shape 3. FBC, Non-FBC Roof

Cover 4. Secondary Water

Resistance 5. Roof-to-Wall Connection 6. Roof Deck

Material/Attachment 7. Opening Protection 8. Gable End Bracing 9. Wall Construction 10. Wall-to-Foundation

Restraint

1. Number of Stories 2. Roof Cover Material 3. Roof Slope 4. Soffit Construction 5. Vinyl Siding 6. Window/Door Water Leak

Potential 7. FBC Roof Cover Age 8. Group I Only: Parapets

and Rooftop Equipment 9. Minimal Condition

Requirements

1. Terrain 2. Design Building Code 3. Design Windspeed 4. FBC, Non-FBC Roof

Cover 5. Opening Protection 6. Roof Deck Material 7. Secondary Water

Resistance

1. Parapets 2. Rooftop Equipment 3. Window/Door Water

Leak Potential 4. FBC Roof Cover Age 5. Minimal Condition

Requirements

Basic Feature Levels General Description

Primary Rating Features 1. Terrain 2 Terrain B, Terrain C2. Roof Shape 2 Hip, Other3. Roof Covering Type 2 Tile, Non –Tile 4. Roof Cover Strength 2 FBC, non-FBC5. Secondary Water Protection 2 No, Yes6. Roof-to-Wall Connection 3 Toe Nail, Clip, Wrap7. Roof Deck Material/Attachment 3 Plywood/OSB (3 nail size/spacings)8. Openings: Protection Level 2 None, ASTM E 19969. Roof Slope 2 4/12, 7/12

10. Soffits 2 Wood, Other11. Number of Stories 2 One, Two or moreTotal No. Combinations of PRF 4,608

10-20 Building Features

Single family exampleEach Feature has multiple levels. > 100,000 possible combinations.

35

Simulation of Damage and LossSimulation of Damage and Loss

C o m p u t e W in d S p e e d a n d D ir e c t io nin O p e n T e r r a in a t T im e t

S a m p le :( 1 ) C o m p o n e n t r e s i s t a n c e s( 2 ) P r e s s u r e c o e f f ic ie n t e r r o r( 3 ) S h ie ld in g lo a d r e d u c t io n f a c t o r( 4 ) B u i ld in g o r ie n t a t io n ( f o r g e n e r ic o r ie n t a t io n )

• C o m p u t e c o m p o n e n t a n dc la d d in g lo a d s o n r o o f c o v e r ,r o o f s h e a t h in g , w in d o w s ,d o o r s , e t c .

• A d d in t e r n a l p r e s s u r e s t o g e tt o t a l lo a d s

• C o m p a r e c o m p u t e d lo a d s f o rr e s i s t a n c e s

• C h e c k f o r d e b r is im p a c t• F a i l a l l c o m p o n e n t s w h e r e

lo a d e x c e e d s r e s i s t a n c e• C h e c k f o r s t r u c t u r a l f a i lu r e

o f r o o f s , w a l ls , e t c . , a sr e q u ir e d

S a m p le w in d s p e e dd e p e n d e n t m is s i l e

im p a c t m is s i l e

C h e c kt o s e e i f a n y

w in d o w s /d o o r sh a v e

f a i le d

H a v e e n o u g hb u i ld in g

s im u la t io n sb e e n

p e r f o r m e d ?

R e c o m p u t ein t e r n a l p r e s s u r ea s a v e r a g e o f a l l

e x t e r n a l p r e s s u r e sa t r o o f a n d

w in d o w s

C o m p u t e D a m a g e /L o s sS t a t i s t i c s f o r G iv e n S t o r m

N o

N o

S t e p S t o r m F o r w a r d t h r o u g h T im eI n c r e m e n t t

Y e s

0

1 8 0

8 . 2 5 8 . 7 5 9 . 2 5 9 . 7 5 1 0 . 2 5 1 0 . 7 5

T im e (U T C )

Pe

ak G

ust

Win

d S

peed

(m

ph)

0

3 6 0

8 .2 5 8 .7 5 9 .2 5 9 .7 5 1 0 .2 5 1 0 .7 5

Win

d D

ire

ctio

n

Y e s

Sample Individual Component Resistances and Load Factors

Fail Components with Load > Resistance

Window/Door Failure?

Next Building Simulation

Damage/Loss Simulation Statistics

Wind Speed & DirectionIn Open Terrain at Time t

Compute Component Loads

Update Internal Pressures

Missiles at Time t

Next Time Step

Simulate all combinations of wind mitigation features

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Example Building Performance Example Building Performance Simulation (from Model Outputs)Simulation (from Model Outputs)

110 mph75 mph 120 mph

143 mph138 mph 160 mph

Loss Reduction Effects of Loss Reduction Effects of Mitigation FeaturesMitigation Features

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Mitigation Feature Terrain B Terrain CMin Avg Max Min Avg Max

No SWR/SWR 0.0% 6.5% 41.9% 0.1% 8.0% 56.2%Gable/Hip 7.7% 31.6% 107.7% 5.1% 35.3% 92.6%2 Story/1 Story 19.3% 51.1% 131.1% 0.0% 40.8% 123.6%Tile /Shingle -8.2% 30.6% 56.1% -28.3% 15.6% 65.3%4:12/7:12 -6.6% 15.4% 104.1% 12.5% 16.3% 120.7%Soffits: Other/Wood 0.8% 7.4% 21.7% 7.1% 24.5% 114.7%Op. Prot: None/Hur 2.5% 17.8% 70.2% 11.8% 61.1% 267.2%Rf-Wall: Toe Nail/Wrap 0.0% 8.2% 78.0% 0.0% 16.6% 78.0%Rf Deck: A/C 0.7% 22.3% 148.1% 1.5% 33.7% 203.8%Rf Cover: non FBC/FBC 17.3% 50.9% 91.2% 6.5% 36.4% 83.6%

One-at-a Time Effects•Min•Mean•MaxUnweighted

GLM•~ 80% r2

•Rank is not particularly meaningful

Florida Building Code UpdatesFlorida Building Code Updates

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Summary of Key Wind Mitigation Code Improvements Ring shank nails for roof sheathing (12-06)

1. Soffits designed for wall pressures (12-06)2. Option for ASTEM D-7158 Class H Shingle (12-06)3. Panhandle WBD Exclusion Removed (3-07)4. Partially enclosed designs no longer allowed (7-07)

Florida Building Code Eras Used in Mitigation Study1. FBC 2001:

• Permit application dates (Mar 1, 2002 to Dec 7, 2006)

• ~Year Built: 2003 through 20072. FBC 2006 (FBC 2004 with 2006 Supplement)

• Permit app date (After Dec 8, 2006)• ~ Year Built after 2008

V. SummaryV. Summary

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Summary-1Summary-1 The 2008 Loss Relativity Study is undergoing review at this time and has not been

officially approved for use. Updated hurricane model has been used in the loss mitigation study. New engineering data on building loads and resistances have been incorporated

into the modeling. Hurricane damage and loss survey data has been used to help validate the models Florida insurance loss data has been analyzed to assess loss reduction of key wind

mitigation features The insurance data analysis supports the general magnitude of wind mitigation rate

differentials. The insurance claim data provided useful data in understanding and validating how

physical damage is adjusted to insured loss. Roof covers dominate losses Loss costs are sensitive to roof cover replacement triggers Old roof covers are more often replaced at lower damage triggers Roof cover condition is also a critical parameter Exterior accessories (lights, electrical connections, gutters, etc) are generally more

vulnerable that the dwelling structure Tree debris removal costs add to the loss costs regardless of the presence or absence of

dwelling mitigation features

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Summary-2Summary-2 Additional mitigation features for Single Family Homes have been

considered. Number of stories Roof cover material Roof slope Soffits Vinly Siding Window/door leak potential FBC Roof Cover Age Minimal Condition Requirements

Roof Cover Roof Deck Strength Window condition

Single Family Loss Relativity Tables Include 4608 entries Two post-FBC building code eras are considered:

FBC 2001 FBC 2004 with FBC 2006 amendments

FBC constructed homes have loss reductions of about 80% from the weakest modeled homes.

FBC constructed homes have loss reductions of about 50% from a typical home.

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Summary-3Summary-3 Key issues in applying wind mitigation rate differentials:

The rate differentials are applied only to that portion of the wind premium that covers the dwelling structure

Attached and detached structures must be excluded from wind mitigation rate differentials.

Exterior structures are very common Exterior structures are highly vulnerable to damage Exterior structures contribute to loss costs at a higher rate than the dwelling Aluminum Frame Structures are particularly vulnerable

Screen Enclosures Carports

Additional work is needed to eliminate these vulnerabilities

New minimal conditions are recommended: Roof cover condition Roof Deck Strength Window/door condition

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Summary-4Summary-4 Insured loss costs vary significantly with terrain, since windspeeds are

dramatically reduced as a result of terrain effects for small buildings: Coastal Open Suburban Treed

Wind mitigation rate differentials are significantly dependent on the deductible. The study only includes 2% deductibles.

Roof cover condition is a major issue. New concepts of coverage and/or consideration of roof condition are needed.

Recommendations prior to implementation: Integrate WBD and terrain research Validate models with new WBD work Add Treed and coastal terrains Regionalize pre-FBC loss relativity tables Incorporate other improvements, including error rates in building inspections Improve definitions These improvements will enable a direct updating of the home rating scale

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Florida’s Decadal Average Annual Florida’s Decadal Average Annual Insured LossesInsured Losses

Simulation of Historical Decadal Hurricanes

2005 Florida Exposure ($1.5 Trillion)

!Florida’s average annual losses by decade,

based on historical storms.Current statewide building stock in 2005 dollars.

2001 Decade is partial average.

If we don’t take a long term approach to loss reduction, future losses will be enormous!

Ground-up AAL by Decade -- 2002 FHCF Exposure ($978 B)

0

2

4

6

8

10

12

1901 1911 1921 1931 1941 1951 1961 1971 1981 1991 2001

Decade

Dec

ade

AA

L (

$B)

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