Learn about the costs and considerations of raising your home.
Factors to consider
Raising a home is a personal solution for protecting a house from flooding. Before deciding to raise a home, there are several factors to consider to ensure that this is a viable option. Factors to consider include: elevation height, elevation technique, the home’s foundation, home accessibility, and additional hazards besides flooding. Additionally, a great first step is contacting the local zoning and building departments.
The height that a home is raised depends on the base flood elevation (BFE) of the area. The BFE is the elevation that flood water is expected to reach during the “base flood.” The BFE is also a regulatory requirement for the elevation of a home that determines the flood insurance premium. The base flood elevation of a property can be found through the community’s FEMA flood insurance rating map (FIRM). Homeowners are also encouraged to add 1 or 2 feet of elevation to the local base flood elevation in order to provide protection from higher flood events. Flood Factor shows the future projections of flooding of a property and the future depths of flooding could be used to determine the extra elevation needed.
Home in the process of being elevated on posts.
Raise the foundation
The elevation technique to raise a home depends on the home’s foundation. Ideally, as much of the original foundation as possible can be maintained in order to save on costs. For all elevation techniques, a design professional must evaluate if a home’s foundation can handle the lifting process and building loads. Piers, posts, columns and pilings are considered open foundations. Slab-on-grade, basement, and crawl space foundations are enclosed foundations that can be elevated onto the previously mentioned open foundations. Homes with these enclosed foundations can also be raised by extending the foundation walls, by extending the walls of the house, or by abandoning the first floor area and building a new second-story living area. For all of these options, the necessary permits must be obtained, the foundation must be evaluated to see if it will support the elevated house, and utility services and lines must be disconnected.
Home that has been elevated by extending the home’s foundation.
Extend the home
To extend, or heighten, a house’s foundation walls, the house is lifted from the foundation and the existing foundation is added to until the intended elevation is reached. Openings are created in the extended foundation so that floodwaters can enter and exit. To heighten the walls of a house, the roof and roof framing must be removed so that the walls can be extended. The walls are then added to, the windows are raised, and a new elevated floor is constructed above the flood level. The area below the raised floor has openings in it so that flood water can enter and exit. To abandon the first floor area and build a new second-story living area, the roof and roof framing must be removed, a second story is built, and openings are created in the abandoned first floor.
Extending the foundation walls, extending the walls of the house, or abandoning the first floor area and building a new second-story living area all raise the living area of a home out of flood levels and create openings in the previously closed foundations so that flood waters can enter.
Open foundation options call for excavation around the old foundation, cutting holes into the foundation so that the network of lifting beams can be installed, and typically removing the old foundation so that the piers, pilings, or columns can be installed.
The image above depicts a home being elevated by extending the foundation walls.
The image above depicts a home being raised by placing the home on piers.
Each of these options requires a large financial investment and the cost of each option varies depending on the existing condition of your home, how much you have to elevate your home, and what option is best for your home depending on the flooding your area experiences. Elevating your home also means that your entry doors are now at a higher level and so you will have to create a new way to access your front door whether that be by stairs, ramps, or elevator. Additional modifications may need to be made to your home to ensure it can withstand the elevation process and can also withstand other hazards such as high winds or earthquakes if your neighborhood is prone to these hazards. The site of your home may not have ideal soil conditions and perhaps relocation could be a better option for some.
Home that has been elevated with columns.