Should You Elevate Your Home?

One of the most common retrofitting methods is elevating a house to a required or desired Flood Protection Elevation (FPE). When a house is properly elevated, the living area will be above all but the most severe floods (such as the 500-year flood). Several elevation techniques are available. In general, they involve (1) lifting the house and building a new, or extending the existing, foundation below it or (2) leaving the house in place and either building an elevated floor within the house or adding a new upper story.

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During the elevation process, most frame, masonry veneer, and masonry houses are separated from their foundations, raised on hydraulic jacks, and held by temporary supports while a new or extended foundation is constructed below. The living area is raised and only the foundation remains exposed to flooding. This technique works well for houses originally built on basement, crawlspace, and open foundations. When houses are lifted with this technique, the new or extended foundation can consist of either continuous walls or separate piers, posts, columns, or pilings.

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Masonry houses are more difficult to lift, primarily because of their design, construction, and weight, but lifting these homes is possible. In fact, numerous contractors throughout the United States regularly perform this work. A variation of this technique is used for frame, masonry veneer, and masonry houses on slab-on-grade foundations. In these houses, the slab forms both the floor of the house and either all or a major part of the foundation. Elevating these houses is easier if the house is left attached to the slab and both are lifted together. After the house and slab are lifted, a new foundation is constructed below the slab.

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For masonry houses on slab-on-grade foundations, some homeowners find it easier to use one of two alternative elevation techniques, in which the house is left on its original foundation. One technique is to remove the roof, extend the walls of the house upward, replace the roof, and then build a new elevated living area inside. The second is to abandon the existing lower enclosed area (the level with the slab floor) and move the living space to an existing or newly constructed upper floor. The abandoned lower enclosed area is then used only for parking, storage, and access to the house.

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In both of these techniques, portions of the original walls will be below the FPE. This approach is appropriate for masonry construction, which is naturally flood-resistant, but not for frame construction, which could easily be damaged by flood waters. This chapter describes and illustrates the various elevation methods and discusses the most important considerations regarding elevation.

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Considerations:

Amount of Elevation - The amount of elevation required is determined by the FPE you have chosen. For example, if your FPE is equal to the Base Flood Elevation (BFE), you will need to elevate your house so that the lowest floor is at or above that elevation. As explained earlier, if your house has been substantially damaged or is being substantially improved, your community's floodplain management ordinance or law will require that your lowest floor be elevated to or above the BFE. If substantial damage and substantial improvement do not apply, you may be able to elevate to any height you wish. But, keep in mind that raising your house to an elevation below BFE not only provides less protection but also results in little, if any, decrease in the flood insurance rate.

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Regardless of whether your house has been substantially damaged or is being substantially improved, you should consider incorporating at least 1 foot of freeboard into your FPE. Elevating a house up to 3 or 4 feet above the existing ground level usually will not have a great effect on its appearance and will require only minimal landscaping and regrading. If you plan to elevate more than 4 feet above the existing grade, you should consider elevating your house a full story, so that you can use the space below the elevated house for parking, storage, or building access.