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HURRICANE MITIGATION

BUILDING CODES FOR SOUTH FLORIDA South Florida Building Code, with its hurricane mitigation provisions, was implemented in September of 1994 to address the weaknesses associated with the building envelope that became evident with Hurricane Andrew.

Three main areas of weakness: roof systems, roof sheathing attachment, opening protection.

BUILDING CODES FOR SOUTH FLORIDA • In 2002 the improved structural portions of the South Florida Building Code were

adsorbed into the Florida Building Code as the High Velocity Hurricane Zone provisions, applicable within Miami-Dade and Broward Counties.

• It was not until the storms of 2005 that the improved structural building envelope provisions of the building code were put to the test in actual conditions.

• Hurricanes Katrina and Wilma represented the greatest test, to date, of the enhanced hurricane mitigation provisions.

• Performance of building envelope systems and components were observed and assessed in “real world” conditions during 2005 hurricane season.

POST HURRICANE WILMA ASSESSMENT BUILDING CONSTRUCTION SUCCESSES (selected examples)

• Sheathing attachment (ring shank nails; mandatory sheathing inspection).

• Gable end construction (roof truss bracing; inspections).

• Window, curtain wall and sliding glass door frames. Glass tested under the current impact tests.

• New shingle roofs (Note: underlayment still in place when shingles were lost).

• Field tile attachment.

Acknowledgment: Information and photos were provided by Mr. Jaime D. Gascon (Miami-Dade RER)

POST HURRICANE WILMA ASSESSMENT

• The requirement that all structures must have windborne debris protection was implemented with the 1994 SFBC and carried forward into FBC HVHZ section.

• Citizens clearly understood the benefits of impact shutters. • This represented the greatest success story regarding damage mitigation.

View of well prepared home which suffered no hurricane damage

POST HURRICANE WILMA ASSESSMENT

• Mechanically attached tile roofs suffered some loss of the first course of tiles. • First course, under high wind induced uplift, experienced rotation of the lower

edge of the tile upward (with the tile fastener near the top edge).

POST HURRICANE WILMA ASSESSMENT

• Hip and ridge caps installed with mortar performed poorly. • Lack of adequate workmanship was evident and the foam did not rise to make

contact with the hip and ridge tile component.

POST HURRICANE WILMA ASSESSMENT

• A remedial measure is to enforce adequate installation and inspection.

POST HURRICANE WILMA ASSESSMENT

• Undamaged new shingle on the left. Damaged older shingle roof on the right.

POST HURRICANE WILMA ASSESSMENT

• Enhanced underlayment attachment for steep roofs was implemented in 1994. • Where shingle losses occurred, the underlayment remained in place contributing

to the water shedding and minimizing water intrusion related losses.

POST HURRICANE WILMA ASSESSMENT

• Channeling effect of the wind created an isolated path of glazing damage to some high rise buildings in the Brickell area.

POST HURRICANE WILMA ASSESSMENT Building Code Modifications:

Miami-Dade Building Code Compliance Office submitted code modifications to:

• Eliminate the mortar set option for hip and ridge tile.

• Require specific post installation testing of hip and ridge cap installation by third party testing agencies.

• Require tile clip be installed along with the other required tile fasteners on each tile along the first course for mechanically attached roof tile systems.

POST HURRICANE WILMA ASSESSMENT Some other apparent weaknesses, observed during post Wilma assessments, were or are being addressed through code modifications:

• Large missile impact debris above 30’.

• Gravel from adjacent roofs causing impact damage.

• Fully adhered roof system recovers over existing gravel roof systems.

• Impact damage to glazed balcony railing systems.

REGULATORY MEASURES TAKEN AFTER WILMA

Unlicensed contractors were taken into custody

BCCO staff checking for contractor licenses at Commercial Checkpoints

WALL OF WIND HURRICANE RESEARCH

2-FAN WOW RENRE 6-FAN WOW 12-FAN WOW

20052005 20072007 20112011

201220121996 IHRC is created 1996 IHRC is created

12-FAN WOW INAUGURATION

12-FAN WOW RESEARCH PROJECTS

FIU 12-fan WOW: Largest, most powerful university research facility for simulating a Cat. 5 hurricane.

12-FAN WOW FLOW MANAGEMENT

12-FAN WOW PRESSURE VALIDATION

HURRICANE MITIGATION Preparing Your Home

1. Protect openings from wind borne debris and pressure 2. Strengthen roof sheathing and roof covering attachments 3. Improve roof paver design and metal roof design 4. Better secure roof top equipment and PV systems 5. Strengthen inter-component connections 6. Strengthen gable ends 7. Reduce Wind-Driven-Rain (WDR) intrusion 8. Reduce surge and flood damage

HURRICANE MITIGATION 1. Protect openings from wind borne debris and pressure  DO NOT tape windows or do ‘Open-a-Window’ to ‘relieve pressure’  Impact glass windows with Miami-Dade County NOA [2 types: glass-

plastic sandwich (regular glass and polycarbonate), ‘glass’ made only of polycarbonate (such as under brand name of Lexan)]

 Shutters with Miami-Dade County NOA [storm panels, accordion shutters, roll-down shutters, Bahama shutters, colonial shutters, flexible screens, see Figures] [shutter do not reduce wind pressure on windows, weak window/door can fail even behind a strong shutter]

HURRICANE MITIGATION  Strengthen vulnerable doors such as reinforcing with slide bolts

(especially inward swinging entry doors and old-style sliding doors)  When putting new doors, use doors with Miami-Dade County NOA  Plan for safety exists from your shuttered house  Reinforce garage doors using braces (or use shutters); strengthen

both the track and the door itself [80% of damage to residential homes stars with a garage door failure]

 Shutter or reinforce sliding glass doors [lip at bottom reduces WDR]