Existing structures that are threatened with coastal flooding or erosion often can be elevated to raise the living space above flood level. If your property is located in a flood zone, you may be required by your town’s floodplain management ordinance to have the lowest structural part of your house be elevated above the base flood level. This elevation factor for safety, called freeboard, is one foot for most Maine communities, with a few communities adopting a higher standard. Consult town officials for your local standards.
If you have an older structure that 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 flood vents, a flow-through foundation, or a pile foundation, especially if structural improvements are substantial, meaning the cost of the improvements meets or exceed 50% of the value of the structure. A substantial improvement to a structure requires bringing the structure up to code, including to floodplain management standards. Increasing the elevation may lower insurance costs.
The concept behind both these foundation types is that water, sediment, and debris can travel through the foundation, thus not applying significant pressure and lateral force to the foundation which can cause structural failure. Both applications can significantly reduce potential flood damage to a structure.
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. 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, 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 or tying down heating fuel tanks. 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, while lowering your flood insurance premiums.
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. Individuals experienced with coastal regulations may not need to consult officials in all cases; however, if in doubt seek regulatory advice before proceeding with a project.
2) Obtain an environmental assessment from a certified engineer or other qualified professional with expertise in coastal geology and flood hazards. 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 or flooding, as well as flood insurance through the National Flood Insurance Program.
4) Develop a mitigation plan if professional and regulatory consultations result in a recommendation that you elevate structures to address coastal erosion or flooding concerns.
5) Be Neighborly. If the plan involves work at or near a property boundary, or if elevating 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 (such as shoreland zoning) may need to be followed when elevating a structure.
7) Need a state permit? If the plan involves alterations below or 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, 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.
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.