a Wind Loss Mitigation Study 2008 Wind Loss Mitigation Study Florida Building Commission Hurricane Research Advisory Committee December 2008 L. A. Twisdale, Ph.D., P. E. Applied Research Associates, Inc Six Forks Road Raleigh, N. C Loss Reduction

a 2 Outline I. Objectives II. Methodology/New Data III. Model Validation/Insurance Losses IV. Building Model Simulations of Mitigation Features V. Summary

a I. Objectives 3

a Objectives 1. 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 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 Develop public domain report 4

a 5 Some Key Loss Relativity Features Roof-to-Wall Connection Roof Shape and Bracing of Gable End Protection of Openings Doors Secondary Water Resistance Roof Deck Attachment Protection of Openings Roof Covering Building Envelope Performance is Critical to Controlling Losses

a 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

a II. Methodology/New Data 7

a 8 Methodology 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

a 9 Modeling and Analysis Approach Modeling and Analysis Approach New Hurricane Hazard Model New Wind Tunnel Data (wind loads, terrain effects) FBC New Insurance Loss Data New Post Storm Physical Damage Surveys Updated Physical Damage And Loss Adjustment Models Loss Costs and Rate Differentials New Component Resistance Data Mitigation Features

a Updated Hurricane Wind Risk 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.

a 11 New Wind Tunnel Data

a 12 Gable Roof Pressures vs. Slope 4:12 12:12 7:12 9:12 Note the reduced loads for steeper slopes.

a 13 New Component Resistance Data 1. Residual Capacity of Shutters 2. Residual Capacity of Laminate Glass Units 3. Impact Capacity of Unprotected Glazing for Shingles 4. Soffit Resistances

a 14 New Hurricane Survey Data Roof Cover Type Tile Attachment Hurricane Charley Damage Survey 370 Houses in Charlotte Harbor Area Post-FBC roof covers have 50% less damage Mortar set tiles have 50% more damage

a Roof Shape and Window Protection 15 Roof Shape Window Protection Gables 33% more roof cover damage Unprotected windows experienced 5 times more damage.

a Performance of Screen Enclosures in Hurricane Charley 16 89% of Alum Frame Screen Enclosures collapsed or had partial frame damage.

a OIR 2007 Exterior Structure Survey Homes surveyed 2. Average of 0.86 Exterior Structures per home 3. Average replacement value was 10.3% of Coverage A, but highly skewed distribution 4. 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

a Single Family Total Exterior Structure Claim Losses 18 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

a III. Insurance Losses/Model Validation Policy Level Data 7 Florida Hurricanes ( ) 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

a Policy Level Data Analysis Approach 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. Raw Data Empirical Loss Functions after Smoothing Loss vs. Windspeed

a Hurricane Charley Swath 21 Post event modeling is based on: Anemometer Data Pressure Data Track History Translation Speed Estimate Rmax, B for Wind Model Produce windspeed and direction time histories at any point Swath shows peak gust at each location Swath is key to analyzing insurance losses, bldg performance 15 Anemometer Measurements

a Hurricane Wilma Swath Anemometer Measurements

a Mean Loss vs Year Built 23 >120 mph winds include some envelope failures. There is a noticeable reduction in loss for recently built homes. >2002

a Pre- and Post-FBC Construction 24 1 Story Single Family 2 Story Single Family Loss Reduction

a One vs Two Stories 25 Pre FBC 2001 Post FBC 2001 Loss Reduction

a Roof Shape 26 Gable vs Hip Company A Company F This differences integrates to about a 20% increase in loss for gable vs hip.

a Opening Protection 27 Loss Reduction

a “Weak” vs “Strong” House 28 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.

a 29 Empirical Functions “track” Building 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.

a Average Loss Reduction Using Insurance Data vs 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

a Insurance 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

a Insurance 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 Roof Cover- 50% of direct loss Screen Encl adds > 50% of direct loss

a IV. Building Model Simulations of Mitigation Features 33

a Important Building Features 34 Basic FeatureLevelsGeneral Description Primary Rating Features 1. Terrain2Terrain B, Terrain C 2. Roof Shape2Hip, Other 3. Roof Covering Type2Tile, Non –Tile 4. Roof Cover Strength2FBC, non-FBC 5. Secondary Water Protection2No, Yes 6. Roof-to-Wall Connection3Toe Nail, Clip, Wrap 7. Roof Deck Material/Attachment3Plywood/OSB (3 nail size/spacings) 8. Openings: Protection Level2None, ASTM E Roof Slope2 4/12, 7/ Soffits2Wood, Other 11. Number of Stories2One, Two or more Total No. Combinations of PRF4,608  Building Features  Single family example  Each Feature has multiple levels.  > 100,000 possible combinations.

a 35 Simulation of Damage and Loss Sample Individual Component Resistances and Load Factors Fail Components with Load > Resistance Window/Door Failure? Next Building Simulation Damage/Loss Simulation Statistics Wind Speed & Direction In 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

a 36 Example Building Performance Simulation (from Model Outputs) 110 mph75 mph120 mph 143 mph138 mph160 mph

a Loss Reduction Effects of Mitigation Features 37 StatisticTerrain BTerrain C RankNo. Stories FBC/non-FBC Roof Shape Roof Cover Roof Deck Roof Slope Opening Prot. SWR Soffits Roof-to-Wall Opening Prot. No. Stories Roof Shape FBC/non-FBC Roof Deck Soffits Roof-to-Wall Roof Slope SWR Roof Cover r2r2 81%79 % One-at-a Time Effects Min Mean Max Unweighted GLM ~ 80% r 2 Rank is not particularly meaningful

a Florida Building Code Updates 38  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 Study 1.FBC 2001: Permit application dates (Mar 1, 2002 to Dec 7, 2006) ~Year Built: 2003 through FBC 2006 (FBC 2004 with 2006 Supplement) Permit app date (After Dec 8, 2006) ~ Year Built after 2008

a V. Summary 39

a 40 Summary-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

a 41 Summary-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.

a 42Summary-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

a 43Summary-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

a 44 Florida’s Decadal Average Annual Insured 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 Decade is partial average. If we don’t take a long term approach to loss reduction, future losses will be enormous!