Hurricane Resistant House
Civil Engineers Improve Houses Against
Hurricanes
April 1, 2007 — Polystyrene blocks used to build the walls in the home have survived
a direct hit from a tornado, and improved version used in houses incorporates concrete
with steel reinforcing inside. On a demonstration hurricane house, brackets are used
for reinforcement. Spray adhesive keeps the driving rain from getting in, and the
shingles are made of fiberglass. Protect windows from breaking from debris with
shutters made from steel, aluminum and polycarbonate. A new flexible material can
also stop debris.
The Great Labor Day Storm of 1935: 423 people dead in Florida. Hurricane Camille devastates
the Mississippi coast in 1969 Wind speeds top 200 mph. Hurricane Katrina in 2005 ... New
Orleans is left under water.
When hurricanes hit, homes are torn apart. Now thanks to science and engineering, a new
"hurricane house" may be able to stand up to some of the strongest storms. And according to
Robert C. Stroh, the house is hurricane-proof up to about 130 mph.
Polystyrene blocks used to build the walls in the home have survived a direct hit from a tornado.
"This white stuff here is the polystyrene, just like a coffee cup is made out of, but inside it is
concrete with steel reinforcing, Stroh, of University of Florida, tells DBIS. "And this is a very
strong building system."
During a hurricane, the roof is usually the first to go. But on the hurricane house, special brackets
are used for reinforcement. Spray adhesive keeps the driving rain from getting in, and the
shingles are made of fiberglass.
Protect windows from breaking from debris with shutters made from steel, aluminum and
polycarbonate. Armor screen, a new material that feels a lot like a trampoline, can also stop
debris. And it's impact-resistant. A metal brace helps keep your garage door intact.
"Things will hit this and they'll bounce off," Stroh says. And if you live inland, simple plywood
may be enough to protect the glass.
Even though the hurricane house can survive a Category 4 hurricane with little damage, it's up to
homeowners to protect their family.
"It's time that the public becomes aware of what options they have," Stroh says. "If you know
there's a hurricane coming I think it's, it's time to get busy and protect yourself."
The American Society of Civil Engineers contributed to the information contained in the TV
portion of this report.
BACKGROUND: Built to withstand winds of more than 140 miles per hour, the new 'hurricane
house' at the University of Floridaýs Fort Lauderdale Research and Education Center officially
opened last spring, just days before the official start of the 2006 hurricane season.
SAFE HOUSE: One of four demonstration facilities located around the state of Florida, the
hurricane house demonstrates that it is possible to build a home that will come through a
category 4 or 5 hurricane with little or no damage. It also shows how existing homes can be
made more hurricane resistant, using materials, products and construction methods that meet or
are better than new state building codes. For instance, there are three different types of window
shutters; impact-resistant doors; a steel 'safe room'; and a garage door that can withstand winds
of more than 150 MPH. Visitors can also see sections of interior walls exposed, revealing
insulated concrete forms to build stronger and more energy efficient homes. The insulated
concrete form uses reinforcement bars and concrete sandwiched between plastic foam sheets.
Although this material is more expensive than regular concrete blocks or wood-frame
construction, in coastal areas where corrosion and storm-surge problems are more prevalent, it's
worth the extra cost.
ABOUT HURRICANES: A hurricane is a type of tropical cyclone, a low-pressure system that
usually forms in the tropics and has winds that circulate counterclockwise near the earth's
surface. Storms are considered hurricanes when their wind speeds surpass 74 MPH. Every
hurricane arises from the combination of warm water and moist warm air. Tropical
thunderstorms drift out over warm ocean waters and encounter winds coming in from near the
equator. Warm, moist air from the ocean surface rises rapidly, encounters cooler air, and
condensed into water vapor to form storm clouds, releasing heat in the process. This heat causes
the condensation process to continue, so that more and more warm moist air is drawn into the
developing storm, creating a wind pattern that spirals around the relatively calm center, or eye, of
the storm, much like water swirling down a drain. The winds keep circling and accelerating to
form a classic cyclone pattern.
RATING HURRICANES: Hurricanes are categorized according to the strength of their winds
according to the Saffir-Simpson Hurricane scale. They are rated from lowest wind speeds
(Category 1) to highest (Category 5). But even lower category storms can cause a great deal of
damage, mostly from storm surges -- when water is pushed towards the show by strong winds
and combines with normal tides to create hurricane storm tides -- and the resulting flooding. The
worst devastation from hurricane Katrina, for example, occurred when flooding caused the New
Orleans levees to fail./p>
Hurricane Resistant Homes
An interesting find from the recent spate of hurricanes in the U.S. is that a particular type of
building structure seems to hold up surprisingly well to the ravages of extreme wind and water.
The reinforced-concrete dome - or “Monolithic Dome” as one company has branded it - has
shown time and time again that it is up to the task of surviving extreme weather conditions like
hurricanes, earthquakes, and even tornadoes. After hurricane Katrina blew through Biloxi,
Mississippi, the concrete-domed New Life Family Church, was one of the few large buildings in
the area left standing. A couple in Pensacola, Florida are so taken with Monolithic Domes that
they rent out their “Dome of a Home” in order to spread the dome gospel. The “Dome of a
Home” has been through three major hurricanes - Dennis, Ivan and Katrina, and survived all
intact.
In addition to being safe, sturdy and weather resistant - Monolithic domes are extremely cheap,
easy to build, and energy efficient. They are also fire-resistant, mold-resistant and impervious to
rot. They’ve become the building type of choice in disaster relief areas, as they can often be
erected in a couple of weeks with minimal materials and resources. Building them basically just
consists of pouring a concrete foundation, inflating a a heavy-duty, dome-shaped “balloon”,
erecting steel rebar scaffolding around that, and then spraying Concrete (Shotcrete) over the
outside. For more information on building a Monolithic Dome, check out The Monolithic Dome
Institute’s guide
Their only major drawback to Monolithic Domes seem to be that they are so insulated that they
usually require air-conditioning and de-humidifiers to keep them dry and ventilated. Also, the
rounded walls make them more difficult to furnish and decorate. And of course your neighbors
might complain.
For more information about Monolithic Domes, see The Monolithic Dome Institute >
Floating House in Netherlands
Unlike the houseboats that line many Dutch canals or the floating villages of Asia, these homes
are being built on solid ground — but they also are designed to float on flood water. Each house
is made of lightweight wood, and the concrete base is hollow, giving it ship-like buoyancy. With
no foundations anchored in the earth, the structure rests on the ground and is fastened to 15-footlong mooring posts with sliding rings, allowing it to float upwards in times of flood. All the
electrical cables, water and sewage flow through flexible pipes inside the mooring piles.
What a great example of turning architectural lemons into lemonade, and being responsive and
accepting of environmental contexts.
Concrete Homes Withstand Storms
Wind testing shows how concrete walls hold up in a hurricane
By Jackie Craven, About.com
These insulating concrete panels will be used for exterior walls.
ConcreteHomes.com
When hurricanes howl, the greatest danger to people and property is flying debris. Carried at such
intense velocity, a 2 x 4 piece of lumber will become a missile that can slice through walls.
Researchers for the Wind Engineering Research Center at Texas Tech University say that concrete
walls are strong enough to withstand flying debris from hurricanes and tornadoes. According to their
findings, homes made of concrete are much more storm-resistant than houses constructed of wood
and steel.
THE RESEARCH STUDY
To duplicate hurricane-like conditions in the laboratory, researchers shot wall sections with 15-pound
2 x 4 lumber "missiles" at up to 100 mph, simulating debris carried in a 250 mph wind. These
conditions cover all but the most severe tornadoes. Hurricane wind speeds are less than the speeds
modeled here. Missile tests designed to demonstrate damage from hurricanes use a 9-pound missile
traveling about 34 mph.
Researchers tested 4 x 4-foot sections of concrete block, several types of insulating concrete forms,
steel studs, and wood studs to rate performance in high winds. The sections were finished as they
would be in a completed home: drywall, fiberglass insulation, plywood sheathing, and exterior finishes
of vinyl siding, clay brick, or stucco.
All the concrete wall systems survived the tests with no structural damage. Lightweight steel and
wood stud walls, however, offered little or no resistance to the "missile." The 2 x 4 ripped through
them.
Reinforced concrete homes have proven their wind-resistance in the field during tornadoes and
hurricanes. In Urbana, Illinois, a recently constructed insulating concrete form home withstood a 1996
tornado with minimal damage. In the Liberty City area of Miami, several concrete form homes
survived Hurricane Andrew in 1992. In both cases, neighboring homes were destroyed.
Monolithic Domes1, which are made of concrete and rebar, have proved especially strong. The sturdy
concrete construction combined with the dome shape make these innovative homes nearly impervious
to tornadoes, hurricanes, and earthquakes.
Want to build your home with concrete? You'll find house plans, illustrations, and lots of information at
Concrete Homes2, the Web site for the Portland Cement Association.
For help planning and constructing a Monolithic Dome home, visit the Monolithic Dome Institute3.