Against the Wind: Protecting Your Home from Hurricane Wind Damage
During a hurricane, homes may be damaged or destroyed by high winds and high
waves. Debris can break windows and doors, allowing high winds inside the home.
In extreme storms, such as Hurricane Andrew, the force of the wind alone can
cause weak places in your home to fail.
After Hurricane Andrew, a team of experts examined homes that had failed and
ones that had survived. They found four areas that should be checked for
weakness-the roof, windows, doors, and if you have one, garage door. In this
brochure, we discuss some things you can do to help make your home stronger
before the next hurricane strikes. You may need to make some improvements or
install temporary wind protection. It is important that you do these projects
now, before a hurricane threatens.
While these projects, if done correctly, can make your home safer during a
hurricane, they are no guarantee that your home won't be damaged or even
destroyed. If you are told by authorities to evacuate, do so immediately, even
if you have taken these precautions.
The Roof
During a windstorm, the force of the wind pushes against the outside of your
home. That force is passed along from your roof to the exterior walls and
finally to the foundation. Homes can be damaged or destroyed when the energy
from the wind is not properly transferred to the ground.
The first thing you should do is determine what type of roof you have. Homes
with gabled roofs are more likely to suffer damage during a hurricane. A gabled
roof looks like an A on the ends, with the outside wall going to the top of the
roof. The end wall of a home with a gabled roof takes a beating during a
hurricane, and those that are not properly braced can collapse, causing major
damage to the roof.
In most homes, gabled roofs are built using manufactured trusses. Sheets of
roof sheathing, often plywood, are fastened to the trusses with nails or
staples, and roofing material is fastened to the sheathing. In many cases, the
only thing holding the trusses in place is the plywood on top. This may not be
enough to hold the roof in place during a hurricane. Installing additional
truss bracing makes your roof's truss system much stronger.
To inspect your roof's bracing, go into the attic. While working in your attic,
you should wear clothing that covers your skin, work gloves, a hat, eye
protection, and a dust mask. If your attic does not have a floor, be careful to
walk only on the wood joists, or install boards wide enough to walk on as you
work. Notice how the plywood is attached to the truss system. If most of the
large nails or staples coming through the sheathing have missed the trusses,
consider having the sheathing properly installed.
Truss bracing
In gabled roofs, truss bracing usually consists of 2X4s that run the length of
the roof. If you do not have truss bracing, it should be installed. You can do
this yourself or hire a professional. Install 2X4s the length of your roof,
overlapping the ends of the 2X4s across two trusses. Braces should be installed
18 inches from the ridge, in the center span, and at the base, with 8 to 10
feet between the braces. Use two 3-inch, 14-gauge wood screws or two 16d (16
penny) galvanized common nails at each truss. Because space in attics is
generally limited, screws may be easier to install.
Gable end bracing
Gable end bracing consists of 2X4s placed in an "X" pattern from the top center
of the gable to the bottom center brace of the fourth truss, and from the
bottom center of the gable to the top center brace of the fourth truss. Use two
3-inch, 14-gauge wood screws or two 16d galvanized common nails to attach the
2X4s to the gable and to each of the four trusses.
Hurricane straps
There are many types of roof design. Regardless of your type of roof, hurricane
straps are designed to help hold your roof to the walls. While you are in the
attic, inspect for hurricane straps of galvanized metal. Hurricane straps may
be difficult for homeowners to install. You may need to call a professional to
retrofit your home with hurricane straps. Check with your local government
building officials to see if hurricane straps are required in your area.
Exterior Doors and Windows
The exterior walls, doors, and windows are the protective shell of your home.
If your home's protective shell is broken, high winds can enter and put
pressure on your roof and walls, causing damage. You can protect your home by
strengthening the doors and windows.
Double entry doors
Most double doors have an active and an inactive or fixed door. Check to see
how the fixed door is secured at the top and bottom. The bolts or pins that
secure most doors are not strong enough.
Some door manufacturers provide reinforcing bolt kits made specifically for
their doors. Check with your local building supplies retailer to find out what
type of bolt system will work for your door. The door bolt materials should
cost from $10 to $40, depending on the type and finish. Doors with windows will
need additional protection from flying debris. See the section on storm
shutters for how to protect windows.
Double-wide garage doors
Double-wide (two-car) garage doors can pose a problem during hurricanes because
they are so large that they wobble as the high winds blow and can pull out of
their tracks or collapse from wind pressure. If garage doors fail, high winds
can enter your home through the garage and blow out doors, windows, walls, and
even the roof.
Certain parts of the country have building codes requiring garage doors to
withstand high winds. You should check with your local government building
officials to see if there are code requirements for garage doors in your area.
Some garage doors can be strengthened with retrofit kits. Check with your local
building supplies retailer to see if a retrofit kit is available for your
garage door. You can expect to pay from $70 to $150 to retrofit your garage
door.
Many garage doors can be reinforced at their weakest points. Retrofitting your
garage doors involves installing horizontal bracing onto each panel. This
horizontal bracing can be part of a kit from the garage door manufacturer. You
may also need heavier hinges and stronger center supports and end supports for
your door.
Check the track on your garage door. With both hands, grab a section of each
track and see if it is loose or if it can be twisted. If so, a stronger track
should be installed. Make sure that it is anchored to the 2X4s inside the wall
with heavy wood bolts or properly attached to masonry with expansion bolts.
After you have retrofitted your door, it may not be balanced. To check, lower
the door about halfway and let go. If it goes up or down, the springs will need
adjusting. The springs are dangerous and should be adjusted by a professional.
If you are unable to retrofit your door, you can purchase specially reinforced
garage doors designed to withstand winds of up to 120 miles per hour. These
doors can cost from $400 to $450 (excluding labor) and should be installed by a
professional.
Storm shutters
Installing storm shutters over all exposed windows and other glass surfaces is
one of the easiest and most effective ways to protect your home. You should
cover all windows, French doors, sliding glass doors, and skylights. There are
many types of manufactured storm shutters available. For more information on
manufactured shutters, check with your local building supplies retailer. If you
install manufactured shutters, follow the manufacturer's instructions
carefully.
Before installing shutters, check with your local building official to find out
if a building permit is required. It is important that you have your shutters
ready now, and that you mark and store them so they can be easily installed
during a hurricane watch.
Plywood shutters that you make yourself, if installed properly, can offer a
high level of protection from flying debris during a hurricane. Plywood
shutters can be installed on all types of homes.
Measure each window and each door that has glass, and add 8 inches to both the
height and width to provide a 4-inch overlap on each side of the window or
door. Sheets of plywood are generally 4X8 feet. Tell your local building supply
retailer the size and number of openings you need to cover to determine how
many sheets to buy.
To install plywood shutters you will need bolts, wood or masonry anchors, large
washers, and 5/8 - inch exterior-grade plywood. For windows 3 feet by 4 feet or
smaller installed on a wood frame house, use 1/4 -inch lag bolts and
plastic-coated permanent anchors. The lag bolts should penetrate the wall and
frame surrounding the window at least 1 3/4 inches. For larger windows, use 3/8
-inch lag bolts that penetrate the wall and frame surrounding the window at
least 2 1/2 inches. For windows 3 feet by 4 feet or smaller installed on a
masonry house, use 1/4-inch expansion bolts and galvanized permanent expansion
anchors. The expansion bolt should penetrate the wall at least 1 1/2 inches.
For larger windows, use 3/8 -inch expansion bolts that penetrate the wall at
least 1 1/2 inches. The tools you will need are a circular or hand saw, a drill
with the appropriately sized bits, a hammer, and a wrench to fit the bolts. To
be safe, use eye protection and work gloves.
Cut the plywood to the measurements for each opening. Drill holes 2 1/2 inches
from the outside edge of the plywood at each corner and at 12-inch intervals.
Drill four holes in the center area of the plywood to relieve pressure during a
hurricane.
Place the plywood over the opening and mark each hole position on the outside
wall. Drill holes with the appropriate size and type of bit for the anchors.
Install the anchors, the plywood, and the bolts to make sure they fit properly.
On wood-frame houses, make sure that the anchors are secured into the solid
wood that frames the door or window and not into the siding or trim. Mark each
shutter so you will know where it is to be installed and store them and the
bolts in an accessible place.
If the opening is larger than one sheet of plywood, you will need to make
shutters with 2X4 bracing. This bracing can be two 2X4s at the middle and
bottom of the two sheets of plywood, evenly spaced, with the 2-inch side
attached to the inside of the storm shutter. Attach the 2X4s to the outside of
the storm shutter with 2-inch, 10-gauge wood screws before installing the
shutter.
The recommendations in this brochure are not intended to replace local building
code requirements or to serve as the only options for protecting your home from
hurricane wind damage. For more information on protecting your home from
hurricane wind damage, contact your local building official; your local
building supply retailer; or a building professional, such as an engineer,
architect, or experienced contractor.