Powerful windstorms disrupt businesses with alarming frequency. When you’re confronting such devastation, it’s important to be aware of, understand, and plan for the forces at work.
From the onset of extreme natural events, owners must navigate complex and dynamic forces to preserve, recover, reconstruct, and recommence operations. Successful mitigation reduces or eliminates long-term hazard risk to life and property in a cost-effective, responsible manner.
Cleaning roof drains, scuppers, and gutters reduces debris-forming dams that can overwhelm roofs – it’s a good thing to do before a disaster, and to keep up with on a regular basis. Strapping fan cowlings and hoods, securing access panels, and anchoring satellite dishes, condensate pipe, and equipment averts unintended openings and keeps these items from becoming windborne debris. Removing loose aggregate from roofs also reduces windborne projectiles.
After Hurricane Wilma crippled south Florida’s infrastructure, more than 3.2 million Florida Power & Light customers were disrupted (1 million of those from 7 to 18 days). In situations like these, it’s best if fuel, food, and hotel rooms (to support disaster assessment teams) are procured in advance. Costly desiccation, dehumidification, generators, and other specialized equipment also need to be prearranged. Roofing materials and glass may require creative acquisition.
It’s important to locate spots where stormwater can enter buildings, including unseen areas. Wind-driven rain can enter failures at roof, wall, or building fenestration, and easily migrate beyond breaches. Failure of rooftop hoods, cowlings, and other HVAC equipment can allow water to pass into air-handling equipment while saturating internal duct linings, filters, and attenuators. Stormwater can infiltrate damaged or collapsed brick and masonry walls. Storm surges along coastal areas can sweep in contaminants and silt.
Building Envelopes & Disasters
Disasters are an unfortunate but important opportunity to understand where loss originates. Research on the effect of hurricanes on buildings reveals that, except for coastal surge areas, windborne debris acting as missile projectiles most often instigates loss. Progressive failure of the building envelope escalates from the first loss of window, door, wall, or roof.
Damage to building envelopes represents only a portion of loss. Contents and inventories reach total insured loss long before failure of the structural frame. Buildings need not be flattened to be devastated. When exposed to a storm’s full force via envelope breach, interiors and contents quickly succumb to wind-driven rain or internal pressurization, or both – greatly amplifying insured losses.
Buildings with "natural porosity" of unprotected fenestration or monolithic glass claddings are particularly vulnerable. Small windborne debris, weighing as little as 2 grams (0.07 ounces) and carried at more than 70 feet per second, carries more than adequate force to break tempered glass. After Hurricane Wilma, broken glass from skyscrapers littered Fort Lauderdale, FL, streets; thousands of windows, primarily from four buildings, were shattered along downtown Miami’s Brickell Avenue. Hurricane Ike ravaged downtown Houston, with windows from several buildings blown out by windborne debris.
Post-storm evidence reveals that, beyond intrinsic strength and wind design, a fortified envelope forms the best line of defense. Estimated maximum sustained hurricane winds during Hurricanes Katrina and Ike remained below code-mandated design wind speeds. Observations of fortified buildings verify that their post-impact envelope behavior is sufficient to resist destructive forces.
Hurricane shutters are a good way to protect susceptible openings. For larger, unprotected fenestrations and glass cladding, impact-resistant laminated glass preserves envelope integrity even when the outer ply is fractured. Impact-resistant overhead rolling service doors defend larger garage, loading, and hanger door openings. Strong ties to structure to provide load path continuity guard against loss of exterior walls.
For roofs, mineral-surfaced modified bitumen membranes perform well in storms; aggregate ballasted and fully adhered single-ply membrane roofs are prone to blow off. Steel roof decks anchored to resist perimeter and corner wind loads, and fixed roof edges, endure turbulent localized uplift pressures. Anchoring large rooftop HVAC equipment keeps units intact. Check out FEMA 543 and FEMA 577 for other strategies.
Once inside, rainwater can sheet across concrete floors and drain throughout the building, soaking porous material like gypsum board, thermal insulation, carpet, wood, and masonry. Migrating water can saturate, erode, and displace applied fireproofing (fibrous and older types containing asbestos are of particular concern). Water can inundate computers and servers, data equipment, motors, lighting, fire alarms, electrical items, or other water-sensitive components.
With time and conducive temperature, water becomes progressively more contaminated, able to promote micro-organisms and mold. Timely intervention to close the building, stabilize interior temperatures and humidity, and extraction of wet and contaminated construction are vital. Guidelines include those from the Institute of Inspection, Cleaning, and Restoration Certification: ANSI/IICRC S500 and S520. For mold or other hazards, industrial hygienists and environmental consultants can help determine courses of action.
You must often act quickly to resume business operations or you risk voiding claims. Understanding duties and limitations dictated by insurance policies can avoid costly mistakes and losses not reimbursed under insurance.
Experienced assessment teams (architects, engineers, estimators, and allied professionals) can help develop a picture of loss and damage. It’s crucial for adjusters to view damage as soon as possible, with you and your assessment team present, to inform adjusters and arrive at agreement on damage. Close examination of post-storm conditions and documentation of damage not visible or apparent is especially critical to identify potential claims.
With a clear understanding of the magnitude and extent of loss and damage, a framework for claims can be formulated and litigation avoided. Photographs accompanying findings provide material support for claims. Thermography or other advanced exploratory tools illustrate damage behind walls. Testing supports claims for hidden damage.
At least 16 states have coastal design provisions in effect. The International Building Code and SEI/ASCE 7 set the national standard for performance-based measures for wind and hurricane design. The Florida Building Code establishes Florida’s Wind-Borne Debris Region and High-Velocity Hurricane Zone. The Texas Windstorm Insurance Association and Texas Department of Insurance mandate special certifications for coastal counties. For critical facilities defined by SEI/ASCE 7, stricter requirements exist. Local authorities may impose other restrictions after disasters.
In coastal and other locations, impact-resistant windows, doors, curtainwall, glazing, cladding, louvers, and uplift-resistant roofing are mandated. ASTM E1886 and ASTM E1996 set impact-resistance standards. Tests simulate inward and outward cyclic pressures and effects of missile debris on various exterior components and materials. Approved impact-resistant products include those from Miami-Dade’s Code Compliance Office Product Approval System (www.miamidade.gov/buildingcode/pc-search_app.asp).
When it comes to reconstruction, building codes are often underestimated. The International Existing Building Code or local codes govern alterations and repairs. Generally, when 50 percent or more of a floor or building is affected, more stringent codes apply.
Handicapped accessibility standards can’t be overlooked, either; accessible routes, restrooms, and other features must be accommodated. For replacement systems, the International Energy Conservation Code, including ANSI/ASHRAE/IESNA 90.1, may put limits on energy consumption and lighting.
Municipal building departments may be overwhelmed after devastating events. In 2006, Fort Lauderdale, FL, faced thousands of backlogged permits just four months after Hurricane Wilma. Offers of mutually agreeable third-party permit reviews or outside inspections may expedite fast-moving projects. City leaders may have to be personally apprised of urgency.
In the ensuing chaos, market forces frequently collide with recovery efforts. Shortages occur as supply chains are disrupted and stocks of materials are depleted. Skilled labor is frequently diverted or unavailable, and electricians and carpenters are especially in demand.
Look outside affected regions. Pre-qualified, trusted construction managers or designated contractors from outside the area may perform work more predictably with higher quality than overtaxed local firms. Demolition can begin immediately after losses are agreed upon.
Weighing schedules carefully and spending judiciously can accelerate completion. Fast-track construction allows a rapid start, but demands flexibility. Depending on available resources, larger or smaller bid packages can be assembled to assign work.
Powerful storms remain certain. Winning strategies for weathering disasters begin with steps to limit damage and loss (especially business interruption). Strengthening the building envelope offers economic and competitive advantages. Planning before catastrophes yields highly effective disaster response.
Limiting effects of water intrusion reduces loss in the aftermath. Reaching agreement with insurers on the magnitude of damage and loss is critical to resolve claims. To resume business quickly, reconstruction must consider the impact of building codes and the effect of market forces. B
Gregory Kissel is president of A359 (www.a359i.com) and has led assessment and reconstruction in the aftermath of Hurricanes Katrina, Wilma, and Ike.