Existing structures that are threatened with coastal flooding or erosion often can be moved up or elevated. If you are located in a flood zone, your town may require that the lowest structural part of your house be a minimum of one foot above the base flood elevation (this is typically the minimum standard), but check with your local code enforcement officer for local ordinances.
If your structure is older and has been flooded and does not meet current standards, or any time you are doing substantial improvements to your structure, consider the cost of elevating the structure using a flow-through foundation or a pile foundation, especially if structure improvements meet or exceed 50% of the value of the structure. In accordance with Floodplain Management regulations, a "substantial improvement" will require the building to be brought up to code, including elevating the building and its utilities.
The concept behind both foundation types is that water, sediment, and debris travel through the foundation, instead of applying pressure and lateral force to the foundation which can cause structural failure. Both foundation types can significantly reduce potential flood damage to a structure.
In some areas, fill can be added below a foundation to increase the elevation of the structure to meet floodplain standards. This technique is not recommended, and may not be allowed in some areas, as it can result in potential increased flood hazard impacts to adjacent properties. Check with local code enforcement for specific standards applicable to your lot.
Many of the state requirements regarding elevation of structures, including a review of techniques, are outlined in Chapter 5 of the Maine Floodplain Management Handbook. Your town may have additional requirements that meet or exceed minimum state standards. Contact your local Code Enforcement Officer for more information about building standards and requirements for each flood zone.
You may also want to review the FEMA Coastal Construction Manual and the FEMA Home Builder’s Guide to Coastal Construction Technical Fact Sheets. The Coastal Construction Manual is available as a CD or in print copy by calling FEMA Publications Distribution Facility at 1-800-480-2520, or through the Maine Floodplain Management Program, and should also be available for review at your local town office or public library.
If you consider elevating your structure, think about making other improvements to make your home more storm and flood resilient, such as elevating utilities. Also, consider elevating your structure over and above the elevation required by your floodplain ordinance, in order to take into account expected rates of sea-level rise and higher future floodplain elevations. This higher "freeboard" (or measure of safety above the base flood elevation) may also reduce flood insurance premiums. The State of Maine has adopted an expected rise in sea level of two feet over the next 100 years.
Follow the steps below to gain the environmental and regulatory information needed for decision making. The steps are listed in general order although some steps may be conducted concurrently.
1) Contact local, state and/or federal regulatory officials. Begin by working with your local code enforcement office to determine if your property is in a FEMA-mapped flood zone and if so, what building requirements apply.
2) Obtain an environmental assessment from a certified engineer or other qualified professional with expertise in coastal geology. In most cases local, state, and/or federal regulators can help direct you to the best professional discipline to assist with your specific project. Sometimes it is helpful to have the consultant completing the environmental assessment and the construction contractor present at regulatory consultation meetings.
3) Evaluate your risk. Check your insurance coverage to make sure you have adequate liability coverage related to loss due to shoreline erosion, as well as flood insurance through the National Flood Insurance Program.
4) If elevating a structure involves work below or within 75 feet of Highest Annual Tide (HAT), develop a site stabilization plan. The plan does not need to be prepared by a professional in all cases; however, a good, clear plan can improve the efficiency and timeliness of any permitting that may be required. Good plans also will be beneficial to the construction contractor and can help avoid costly mistakes during the construction process.
5) Be Neighborly. If the plan involves work at or near a property boundary, or if moving a structure may affect an abutter’s “viewshed,” consider sharing the plan with the abutter(s) to make sure they fully understand the work to be performed and the potential impact to their property. This consultation is a courtesy at this stage, and not a regulatory mandate; however, obtaining “buy in” from abutter(s) can potentially avoid neighbor disputes that may lead to costly permitting and/or construction delays.
6) Need a local permit? Share plans with local code enforcement in order to determine what, if any, town ordinances may need to be followed when moving structures. Local shoreland zoning requirements will determine the acceptable location(s) for structures.
7) Need a state permit? If the plan involves alterations within 75 feet of highest annual tide (HAT), within or adjacent to another protected natural resource as defined by the Maine Natural Resources Protection Act such as a sand dune, or within a development permitted by the Site Location of Development Act, a state permit will likely be required. When possible, plan to meet standards of a permit-by-rule to simplify the state regulatory review process; otherwise an individual permit may be required. Alterations to a development or a lot within a development permitted under the Site Location of Development Act may require the revision or amendment of the development’s permit. Refer to Chapter 305 (Permit by Rule), Chapter 310 (Wetlands) and Chapter 355 (Coastal Sand Dune Rules) for additional requirements relating to impacts to coastal sand dunes associated with elevating structures.
8) Need a federal permit? If the plan involves work below the highest annual tide (HAT) and/or in a freshwater wetland or habitat for endangered or threatened species, a federal permit(s) under the Federal Clean Water Act and Rivers and Harbors Act may be required. Share the plan with all applicable federal authorities in order to determine what permits may be necessary.
9) Hire qualified contractors who are experienced with the best practices associated with construction in or adjacent to natural resources.