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Article originally from American Chemistry magazine

From the hurricane that hit Galveston, Texas, in 1900—the deadliest weather disaster in U.S. history, claiming 6,000 to 12,000 lives—to Hurricane Katrina in 2005—the costliest U.S. hurricane on record, causing an estimated $96 billion in damage—the impact of tropical cyclones on American life and property over the years has been significant.

The Atlantic hurricane season takes place each year from June 1 to November 30, with maximum activity in early to mid-September.  Hurricane hazards come in many forms, including storm surges, high winds, tornadoes, and flooding.  It is imperative for families, businesses, and communities alike to have a plan that addresses all of these hazards.

Hurricane hazards
A storm surge occurs when the force of winds swirling around the storm push water toward the shore.  The advancing surge combines with normal tides to create a hurricane storm tide, which can increase the water level by 15 feet or more, causing severe flooding in coastal areas. Since much of the United States coastlines’ densely populated Atlantic and Gulf Coast lie less than 10 feet above the mean sea level, the danger from storm tides is tremendous in these areas.

Even in communities hundreds of miles from the coast, inland flooding can be a major threat, as intense rain falls from huge tropical air masses.  In a study by the Federal Emergency Management Agency (FEMA) from 1970 to 1999, freshwater flooding accounted for 59 percent of U.S. tropical cyclone deaths. In total, 63 percent of U.S. tropical cyclone deaths during that period occurred in inland counties.

The intensity of landfalling hurricanes is expressed by the Saffir-Simpsons Hurricane Scale in terms of categories that relate to both wind speeds and potential damage.  A Category 4 hurricane, for example, would entail winds between 131 and 155 miles per hour and could cause 100 times the damage of a Category 1 storm.

Hurricane-force winds can easily destroy poorly constructed buildings and mobile homes, while extensive damage to trees, towers, water and underground utility lines (due to uprooted trees), and fallen poles can cause considerable disruption.  Meanwhile, various objects and debris—including signs, roofing materials, and small items left outside—become flying missiles.

Keeping homes safe
Learning from these hazards in past storms, chemistry companies continue to innovate and manufacture new products that can help keep people and their homes safe during a hurricane.

Inland flooding can become a major threat, as intense rain falls from tropical air masses.

Much of the home investment loss associated with hurricanes and other serious storms results from water entering the home when roof coverings or sidings are blown off.  This leaking is the main cause of rot and mold that can then lead to major structural damage and potential health problems for homeowners.

Chemical-based materials help to produce roofing membranes, window and door flashings, and weather barriers that protect structures from the types of wind and water damage often caused by hurricanes.

Security overhead
In 2004, FEMA published recommendations for the use of fully adhered roofing underlayments as an enhanced secondary water barrier for homes in both coastal and inland hurricane-prone areas.  In the event roof coverings are blown off or water manages to get underneath them, these underlayments are key to preventing water infiltration.

First, roof flashing is generally applied around objects that protrude from the roof of a building, such as chimneys and pipes, to deflect water away from seams or joints.

Then, a synthetic water-shedding roof underlayment, consisting of a rubberized asphalt surface backed by a layer of high-density, cross-laminated polyethylene, can be applied over the entire roof deck (the material layer between the primary structural components) to resist water penetration due to water back-up behind ice dams or wind-driven rain.  Together, these products provide unmatched durability and weatherability.

Protecting the surroundings
Beyond the roof, a home’s doors and windows can also become major leak zones if they are not properly flashed.  Depending on the climate,a waterproofing membrane such as bituminous fabric or plastic sheet material is typically placed under windowsills or door thresholds to prevent water from entering a wall at those points.

After a major hurricane season in 2004, the Florida Home Builders Association (FHBA) released a 65-page report on water intrusion that cited flashing as one of the most important elements for ensuring water does not penetrate the wall system.

Flexible flashing products can be used to seal the most vulnerable spots of a house, including windows, doors, corner boards, stucco finishes, masonry walls, and other non-roof detail areas.  Highly conformable, self-adhering waterproofing membranes form a weathertight barrier around unwanted openings in the wall sheathing system.  The following are some signs of water damage and, therefore, the need for flashing:

• Leaks or breaks in seams around window trim and sills
• Uneven door frames
• Discolored plasterboard
• Peeling wallpaper
• Deterioration or separation of the roof deck from the rest of the house
• Chipped or cracked stucco finishes
• Mold, mildew, or rot in the walls, insulation, and electrical systems
• Missing, cracked, or blistered paint inside the home

Being prepared
According to the U.S. Census Bureau, as of July 1, 2008, an estimated 35.7 million people—roughly 12 percent of the nation’s population—lived on the coastal portion of the states stretching from North Carolina to Texas, the areas most exposed to Atlantic hurricanes.

In these areas, it is especially important for homeowners to understand hurricane hazards, their consequences, and what actions can be taken to be prepared:

Develop a family plan:

• Discuss the types of hurricane hazards that could affect your family
• Determine your home’s vulnerability to storm surge, flooding, and wind
• Determine the safest areas in your home or within the community to ride out each hurricane hazard
• Choose escape routes from your home and places to meet
• Ask an out-of-state friend to serve as a family contact, so all of your family members will have a single point of contact in an emergency
• Post emergency numbers by your telephones and make sure your children know how and when to use 911
• Use a National Oceanic and Atmospheric Administration (NOAA) weather radio.  Replace its battery every six months, as with smoke detectors
• Take first aid, cardiopulmonary resuscitation (CPR), and disaster preparedness classes

Create a disaster supply kit:

• Water (at least one gallon daily per person for three to seven days)
• Food (at least enough for three to seven days) and utensils
• Blankets and pillows
• Clothing, especially seasonal apparel, rain gear, and sturdy shoes
• First aid kit, medicines, and prescription drugs
• Any special items for babies and the elderly
• Toiletries, hygiene items, and moisture wipes
• Flashlights with batteries
• Fully charged mobile phone with extra battery, as well as a landline phone (not cordless)
• Cash (including some small bills) and credit cards
• Keys
• Tools
• Important documents in a waterproof container or resealable plastic bag
• Pet care items
• Toys, books, and games

The most important precaution to reduce damage to your home and property is to protect areas where wind can enter, including the roof, straps, shutters, doors, and garage.  Strengthening the exterior of your house will prevent wind and debris from tearing large openings in it.

• Find out if your home meets current building code requirements for high winds.  Experts agree structures built to meet or exceed these provisions have a much better chance of surviving violent windstorms.
• Protect all windows by installing commercial shutters or 5/8-inch plywood panels.
• Reinforce all garage doors to withstand high winds.
• Designate an interior room with no windows or external doors as a ‘safe room.’
• Before hurricane season, assess your property to ensure landscaping and trees do not pose wind hazards.  Trim deadwood and weak or overhanging branches from all trees.  Consider landscaping materials other than gravel and rock.
• A great time to start securing or retrofitting your house is during other renovations or an addition. Contact local building code officials for details.
• Flood damage is not usually covered by homeowner’s insurance.  Check your policy.  The National Flood Insurance Program (NFIP) is a pre-disaster flood mitigation and insurance protection initiative to reduce the escalating cost of disasters by making federally backed insurance available to residents and business owners.
• Prepare your home before evacuating by boarding up doors and windows, securing or moving all yard objects indoors, and turning off all utilities.

Learn more about hurricane preparedness.

With files from W.R. Grace & Co.  Additional resources are available at www.hurricanes.gov/prepare and Red Cross.

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