Other Ways to Make Your House Floodproof
The Way You Rebuild Today Will Make a Difference Tomorrow
Release Date: November 20, 1998
Release Number: 1257-037
» More Information on Texas Severe Storms, Flooding and Tornadoes
SAN ANTONIO, Texas -- If you are thinking about rebuilding after the floods, and you've decided that elevating your house is not right for your situation, you may want to think about some of the other options available to protect your home from future flooding.
Whatever you decide to do, check with local officials before you start any work rebuilding. Local ordinances and codes determine in large part what you can and cannot do - and what you should do.
If your home is not in a special flood hazard area and if local regulations allow, you should consider the following options:
Wet Floodproofing means modifying the uninhabited portions of the house, such as a crawlspace under the house, so that floodwaters can get in but won't cause significant damage. By letting water in, the pressure is equalized between the outside and inside of the house, greatly reducing the chances of the walls collapsing. It is a practical solution for parts of the house that are not living space.
If you decide to wet floodproof, service equipment such as a furnace or water heater must be protected and new materials should be impervious to water damage. You cannot live in a wet-floodproofed house as long as floodwaters remain inside.
Remember that wet floodproofing does nothing to alleviate the threat of damage from fast-moving floodwaters, which are often a major cause of damage.
Dry Floodproofing is done by making a house watertight below the flood protection elevation so that floodwaters cannot enter. This is done by sealing the walls with waterproof coatings, impermeable membranes or supplemental layers of masonry or concrete. Doors, windows, and other openings also must have permanent or removable shields; backflow valves must be installed in sewer lines and drains.
Before dry floodproofing, you need to consider the flood depth and duration, flow velocity and potential for wave action and flood-borne debris. Dry floodproofing may not be used to bring your substantially damaged or substantially improved house into compliance with local floodplain management laws.
Levees and floodwalls are flood protection barriers that can be built to protect a house. A levee is typically made of earth, while a floodwall is normally built of concrete and/or masonry. Levees are usually limited to six feet in height, while floodwalls normally remain at four feet or less. Both levees and floodwalls should be built one foot higher than the base flood elevation to provide extra protection.
These structures are built around a house to keep floodwaters at bay. They must be strong enough to withstand the high pressure exerted by floodwaters on one side.
Placement of levees and floodwalls is important because they can have a significant impact on surrounding properties. They can divert floodwaters onto nearby land and block or impede the flood's flow, which in turn can send the flood into areas previously flood-free.
Some communities prohibit the construction of levees and floodwalls in the floodplain and floodway, so be sure to check with your local permitting agency before undertaking these projects.
Relocation-moving your house out of the flood hazard area-offers the greatest protection from flooding, but it is also the most expensive method. If you are seriously considering moving a house, you should take into account the house's condition; its size, design, and shape; possible routes between the old and new sites; and the length of time during which the house cannot be occupied.
If you decide to relocate your house, pay special attention to the new site. Consider the natural hazards that might be faced in the new location, how utilities can be connected, the site's accessibility and local zoning ordinances. You should involve your design professional and a movi0ng contractor in the process so you won't face any surprises as the move occurs.
Once the house is moved and fully set-up, the old site must be restored according to local requirements. This can involve removing the old foundation, filling and grading the site, removing the old utility systems and planting to restore vegetation.
Demolition is sometimes the most effective retrofitting method when there is no better way to rebuild a severely damaged house. Often it is easier to tear down a house that is extensively damaged or structurally unsound and start over than it would be to make repairs. If the house has been damaged by flooding and is in the regulatory floodplain, salvaging it can be an expensive and complicated process.
Anyone thinking about tearing down a house and rebuilding in another area outside the floodplain also should take into account what to do with the remaining vacant property. It may be difficult to sell because of its location. It must be restored according to local regulations.
If you have questions about retrofitting measures, call 1-800-628-5769 and ask to speak to a FEMA mitigation counselor.
Last Modified: Tuesday, 20-Jan-2004 10:10:04