Water can invade homes in a number of ways, especially when it’s being blown horizontally.  To emphasize how important it is to seal areas to prevent water intrusion, consider this:

Hurricane force winds can blow water uphill.  In fact, a 74 mile per hour wind (the lowest hurricane wind) can blow water up a wall about 4 inches.  A 110 m.p.h. wind can blow water up a wall nearly 6 inches.  With that kind of force, gallons of water can be pumped through even very small cracks in walls and end up in the wall cavity or living space.

Consequently, penetrations in walls can allow enough water into a house to cause lots of damage.  If there is a loss of power for air conditioners (AC) or dehumidifiers to dry things out, that water damage could lead to mold. 

Look for holes where wires, cables and pipes enter and exit the house.  In addition to openings for cable TV and telephone lines, seal all the way around electrical boxes and circuit breaker panels.  Pipe penetrations include AC refrigerant lines, AC condensate lines, water heater pressure relief lines and water pipes.  Also seal cracks around wall outlets, dryer vents, bathroom and kitchen vents and electrical devices such as wall lights. 

Goose neck vents, turbine vents and a variety of roof vents that work in ordinary wind probably will not keep out water in a hurricane.  Most are not designed to operate in strong winds and few are designed to handle the wind loads induced.  The vents should be removed or anchored more securely and well sealed.  If you remove them, securely seal the opening with a cover that will not be blown or sucked off.

Windows and Doors: Check for leaks around your windows and doors, especially near the corners. Check for peeling paint, it can be a sign of water getting into the wood. Inspect for discolorations in paint or caulking, swelling of the window or doorframe or surrounding materials.

Foundation and Exterior Walls: Seal any cracks and holes in external walls, joints, and foundations, in particular, examine locations where piping or wiring extends through the outside walls. Fill all cracks in these locations with sealant.

Flashing: Flashing, which is typically a thin metal strip found around doors, windows, thresholds, chimneys, and roofs, is designed to prevent water intrusion in spaces where two different building surfaces meet.

Vents: All vents, including clothes dryer, gable vents, attic vents, and exhaust vents, should have hoods, exhaust to the exterior, be in good working order, and have boots.

Attics: Check for holes, air leaks, or bypasses from the house and make sure there is enough insulation to keep house heat from escaping. Among other things, air leaks and inadequate insulation results in ice damming. If ice dams collect around the lower edge of a roof, rain or melted snow can back up under the shingles and into the attic or the house. Check the bottom side of the roof sheathing and roof rafters or truss for water stains.

Basements: Make sure that basement windows and doors have built-up barriers or flood shields. Inspect sump pumps to ensure they work properly. A battery backup system is recommended. The sump pump should discharge as far away from the house as possible.

Expansion Joints: Expansion joints are materials between bricks, pipes, and other building materials that absorb movement. If expansion joints are not in good condition, water intrusion can occur. If there are cracks in the joint sealant, remove the old sealant, install a backer rod and fill with a new sealant.

Exterior Wood Sheathing and Siding: Replace any wood siding and sheathing that appears to have water damage. Inspect any wood sided walls to ensure there is at least 8" between any wood and the earth.

Drywall: Since drywall is an extremely porous material and is difficult to dry out completely, damaged areas should be replaced if any signs of moisture are present. One way to protect drywall from moisture intrusion in the event of a flood is to install it slightly above the floor and cover the gap with molding.

Exterior Walls: Exterior walls should be kept well painted and sealed. Don't place compost or leaf piles against the outside walls. Landscape features should not include soil or other bedding material mounded up against walls.

Soffits: Keeping soffits in place can help keep water out of your house.  Aluminum and vinyl soffits were often blown off homes during the 2004 hurricane season. An inexpensive recommendation for soffit strengthening is to apply a bead of polyurethane sealant along the joint between the edge of the channel and the wall, installing sharp pointed stainless steel screws through the fascia and channels so that they connect the soffit material to the edge supports, and applying sealant in the grooves where the fascia material butts up against the fascia and wall channel.

Keeping shingles on your house is extremely important.  Check to make sure they are well secured to the roof, particularly along the roof edges. 

A common problem is that edge shingles are not well fastened or extend beyond the drip edge more than the 1/4” typically recommended for high wind areas.  Once the perimeter shingles lift off, a peeling process starts and creates a domino effect.

The attachment of perimeter shingles can easily be checked by gently trying to lift the lower edge of the shingle.  If it comes up without much effort (older shingles become brittle and may crack when bent too much), then you should secure them, which is easy. 

If you find that a lot of shingles, including ones away from the edge, are poorly adhered, budget for a new roof in the near future.  There have been significant improvements in shingles and the adhesive strips that anchor them to the ones below.  New high wind rated shingles installed according to manufacturer’s recommendations for high wind areas and with extra edge sealing performed very well in the hurricanes of 2004.

Repair or replace shingles around any area that allows water to penetrate the roof sheathing. Leaks are particularly common around chimneys, plumbing vents and attic vents. To trace the source of a ceiling leak, measure its location from the nearest outside wall and then locate this point in the attic using a measuring tape. Keep in mind that the water may run along the attic floor, rafters, or truss for quite a distance before coming through the ceiling.

Use roofing cement in 10 oz. caulk tubes that fit ordinary caulk guns to secure roof shingles.  It's inexpensive and one tube is enough for about 25 feet of shingles.  Perimeter shingles include those along the eaves and gable edges, plus the ones on the ridge and hips.  Place three 1" diameter dabs under each shingle tab (near the edges and in the middle).  On gable ends, secure the three shingle tabs closest to the gable edge.   If the roof is not too steep, an able-bodied person with practical skills should accomplish this in just a few hours.

Limiting possible sources of wind-borne debris before a storm will help protect your home and those around you.

Replace gravel/rock landscaping materials with shredded bark.  In a particularly strong hurricane, gravel has been found in mail boxes and has shredded vinyl siding.

Limit yard objects like garden spheres or gnomes, and remove chairs or other furniture when not in use, so there’s less work to do to prepare for a hurricane.

Landscaping: Keep trees trimmed so that branches are at least 7 feet away from any exterior house surface. This will help prolong the life of your siding and roof and prevent insects from entering your home from the tree. Vines should be kept off all exterior walls, because they can help open cracks in the siding, which allows moisture or insects to enter the house.

Be prepared to move anything outside that can become flying debris into your house or garage. 

Source:  Institute for Business and Home Safety