How should I build in areas near the Limit of Moderate Wave Action (LiMWA)?

Building codes use the LiMWA to identify the "Coastal A Zone" (e.g., the area where base flood wave heights are between 1.5 and 3 feet), where certain design and construction requirements are instituted. Because of the presence of damaging waves, VE Zone design, construction, and certification practices are recommended, though not required by the National Flood Insurance Program, in the LiMWA. Recommendations include:

  • Use open foundations (pile or pier) designed to resist all base flood conditions (waves, high velocity flow, erosion and scour, floodborne debris);
  • Since waves and debris will be impacting the floor joists and other foundation elements during the base flood, elevate the bottom of the lowest horizontal structural member supporting the lowest floor above the base flood wave crest elevation;
  • Use flood-resistant materials above the level of the walking surface of the lowest floor in the event that future flooding exceeds the lowest floor level;
  • Assure that connections between the foundation and the elevated building are capable of withstanding simultaneous wind and flood forces;
  • Use the space below the lowest horizontal structural member for parking, access, or storage only. Adding sufficient freeboard to allow parking beneath the building will not only reduce future flood damages, but will also lower flood insurance premiums; and
  • Use screens or latticework if space below the elevated floor must be enclosed.

Show All Answers

1. Why does FEMA map coastal flood hazards?
2. I have never seen a flood here. Why is this area shown as a high risk flood zone?
3. A recent large storm hit near my house and it didn’t flood; are you sure these maps indicate the current flood risk in my area?
4. What is the difference between a Zone VE and a Zone AE flood hazard designation?
5. Why did FEMA choose the 1-percent standard?
6. How does the preliminary map issuance change my flood insurance rate?
7. Why is FEMA creating new coastal maps when there are so many other public priorities?
8. What different methodologies are used in performing coastal studies and why?
9. Why are there multiple flood studies occurring in my community?
10. Are the flood hazards shown on the Flood Insurance Rate Map based on historic coastal flood events?
11. How accurate are coastal flood study results?
12. How can coastal flood studies be made more accurate?
13. If there is a margin of error in coastal flood studies, how can FEMA be sure that its flood insurance mandatory purchase requirement is not being applied to structures outside the Special Flood Hazard
14. At what scale are coastal flood studies performed?
15. Are the flood study results appealable?
16. Is it possible for community officials or individual property owners to appeal a coastal study when FEMA used supercomputers to obtain the results presented on the Flood Insurance Rate Map (FIRM)?
17. Why isn't FEMA using the latest two-dimensional wave models to estimate wave effects over land?
18. Why is the Base Flood Elevation (BFE) near my property different than the BFE near my neighbor’s property?
19. What is the Limit of Moderate Wave Action (LiMWA)?
20. How is the LiMWA mapped?
21. How should I build in areas near the Limit of Moderate Wave Action (LiMWA)?
22. Does the LiMWA impact flood insurance premiums?
23. What is a Primary Frontal Dune (PFD)? How are the PFD lines drawn?
24. How long does it take to conduct a coastal flood study?
25. Why does a coastal study take so long?
26. What stakeholders are involved in conducting a coastal flood study?
27. Why is the modeling for a coastal study so complex?
28. How long is the appeal process and compliance period?
29. How is FEMA accounting for sea level rise and climate change on the FIRMs? Does sea level rise/climate change affect the FIRMs?
30. How are the FEMA maps different from NOAA’s inundation/evacuation maps?
31. Why isn’t our beach nourishment and/or dune construction project included in the coastal map study analysis and resulting mapping?
32. How do you assure that the analysis includes enough information to depict the flood risk near my home?
33. What is the Joint Probability Method?
34. What is a synthetic storm?
35. Does FEMA include tsunamis on the flood hazard maps?
36. What is the Coastal Barrier Resources System (CBRS)?
37. What is the CBRS digital conversion project?
38. Why shouldn’t the FIRM be used to make CBRS determinations?
39. Why did FEMA remove some survey benchmarks?
40. Why am I in the mapped SFHA if my house is on a dune above the BFE?
41. What are some mitigation actions that coastal communities can take?
42. Can a community require higher BFEs to encourage higher building standards?
43. My homeowners insurance will not cover the additional cost to elevate. How is that fair?
44. Is it considered “new construction” if I replace my home after a disaster event?
45. Can I build on my property in the floodplain?
46. I can’t afford to elevate my home out of the floodplain. Is there any assistance available for me?
47. Why does FEMA promote development in the floodplain by offering flood insurance?
48. Why am I required to purchase flood insurance?
49. When am I required to purchase flood insurance?
50. Who determined that I was required to purchase flood insurance?
51. What information should I bring with me to meet with a flood insurance agent?
52. Can I shop around for flood insurance?
53. Why should I purchase flood insurance?
54. What can I do to get the cost of my flood insurance premium to be as low as possible?
55. Are there any modifications that I can make to my home to reduce my flood insurance rate?
56. Are extensive engineering studies needed in order to obtain a Letter of Map Amendment (LOMA)?