Home Building Articles
Protecting Homes from Hurricanes
July 08, 2009
Hurricanes are one of nature's most destructive forces, as witnessed in 2005 when
Hurricane Katrina pummeled the Gulf Coast. FEMA estimates that Katrina killed over
1,300 people, displaced 450,000 people, and wrecked over 300,000 single-family homes
throughout Louisiana and Mississippi. Most of the havoc caused by Katrina was flood-related,
due to levee failures in New Orleans. Storm surges created waves that were more
than 20 feet high in some places and carried debris that destroyed buildings.
Hurricane resistant design
Most structural failures during a hurricane are a result of inadequate design and
construction practices. Conventionally, homes have several weak points, such as
windows, doors, corners, connections between floors, and connections between the
roof and walls, all of which make homes vulnerable to wind damage. Builders need
to keep these weak points in mind, applying design and construction methods that
enable homes to resist hurricane winds. These general guidelines help ensure a home
is built to withstand hurricanes.
- Build the home low. The lower the home is, the better, because the wind has less
area on which to blow and exert pressure on the home.
- Build a hip roof. Hip roofs reduce winds better than gable roofs.
- Build a roof with a 5:12 slope. A shallower slope reduces the wind forces against
the roof.
- Build a wind-resistant roof. If you install shingles, use wind-resistant shingles.
If you install tiles, attach them with mortar or foam, and secure them with four
to six fasteners per tile. They won't be blown off the roof as easily.
- Reduce the sizes of overhangs. Smaller overhangs are harder for wind to lift up
- Don't locate windows near corners. Any opening you put in the corners will weaken
the home. Windows built at corners make the home more susceptible to being racked
out of shape when the wind blows.
Roof sheathing
Builders can use several strategies for keeping the roof on the home during a hurricane.
Plywood is preferable to OSB decking, because it's sturdier. High-quality fasteners
and hurricane-proof nailing patterns help keep the roof from lifting up. Decrease
the spacing of fasteners on the roof deck to 4" on center. Closer spacing keeps
the roof more secure to the home and prevents it from lifting up. Use nails and
screws with a longer shank and larger head, and use a closer spacing pattern with
more nails and screws. It's important to check your work, because you can easily
miss areas with a nail gun. To protect the home against water intrusion, the gaps
between plywood sheets should be sealed with a peel and stick tape.
Shear panels
In zones with a high risk of hurricanes, conventional wall bracing isn't enough.
Shear panels are required at critical areas, usually at the corners. A shear panel
is a wall segment that's engineered to resist hurricanes more effectively than the
average wall. The strength of shear panels comes from additional fasteners, thicker
sheathing, additional studs, anchors, and hold downs. The shear panels can be either
constructed at the jobsite or supplied as preassembled units, ready to install.
Preassembled panels are a convenient solution for builders, because they're constructed
and inspected by the manufacturer. Builders need to worry only about fastening them
in place properly and checking the installation.
Reinforced garage doors
As the largest opening, a garage door is the weakest point in any home. Garage doors
are typically made of lightweight materials, making it easy for hurricane winds
to tear them apart. Once the garage door is destroyed, wind can rush into a home,
causing building failure. The best way to prevent damage to the garage door is to
install a preassembled reinforced garage door. Several manufacturers offer garage
doors that are strengthened with a bracing system of aluminum bars, brackets, and
a steel track. These features prevent the door from blowing in.
Storm rooms
Storm rooms provide a place for homeowners to survive a hurricane without injury.
Debris, such as signs, roofing material, and small items left outside become flying
missiles in hurricanes. Storm rooms are built with stronger materials than standard
homes that allow them to resist wind loads and penetration by these flying objects.
Some of the materials that have been proven to withstand impact include concrete
masonry walls with vertical and horizontal reinforcement, plywood-covered wood stud
walls filled with dry-stacked concrete blocks, and steel sheets combined with plywood
sheathing and wood studs.
Like shear panels, storms rooms can be built onsite or installed as manufactured
units. They're designed to be a "room within a room," so that they will remain intact
even if the surrounding home is destroyed. The storm room should be accessible from
all parts of the home to allow homeowners to reach it quickly and safely during
a storm. The walls should be anchored to the foundation to resist overturning and
lifting up. All sides of the room, including the walls, roof, and door, must be
able to resist penetration by windblown objects.
Homeowner education
Studies show that homeowners who live in coastal areas are willing to pay more for
hurricane protection and peace of mind. In addition to providing buyers with a hurricane
resistant home, give them information about what to do after a hurricane strikes
to ensure their health and safety.
Make sure homeowners are aware of what needs to be inspected and what precautions
they should take before entering their home. They should have the heating and cooling
system checked by a service technician before running it. If water has entered the
system, mold can be blown through the home if the system is turned on. If the electricity
is off, homeowners should have a portable generator on hand to power equipment and
remove standing water. In the basement or crawlspace, you can remove standing water
by using a wet-dry shop vacuum, an electric-powered water transfer pump, or a sump
pump. To aid drying, open windows and doors, and use fans and dehumidifiers. Fans
should be placed at windows and doors to blow air out of the home.
To learn more about protecting homes and homeowners from hurricanes, visit: www.fema.gov
*Source: HGTVPro.com