Technical Standards

1. NFIP National Flood Insurance Program Administered by FEMA Technical Standards

2. TOPICS • Elevation • Wet Floodproofing • (Dry) Floodproofing of Non-residential Structures

3. MORE TOPICS . . . • Utilities and Building Systems • Manufactured Home Standards

4. Elevation • Requirements in A and V Zones • Elevated Foundations • FEMA’s Technical Bulletins and Technical References

5. Elevation Requirements for Zones AE, AH, and A1-30 • All new construction and substantial improvement shall have the Lowest Floor, including basement, elevated to or above the BFE • The reference level for the lowest floor is measured at the top of the sub-floor

6. Elevation Requirements for Zone AO... All new construction or substantial improvement, shall have the lowest floor, including basement elevated above the highest adjacent grade to a height equal to or exceeding the depth number specified in feet on the FIRM.

7. ...Elevation Requirements for Zone AO If no depth number is specified, then the Lowest Floor must be elevated at least two feet above the highest adjacent grade.

9. Elevation Requirements for Zones VE & V1-30... • 1. All new construction and substantial improvement shall be elevated on adequately anchored pilings or columns…

10. ...Elevation Requirements for Zones VE & V1-30... • ...and securely anchored to such pilings or columns so that the lowest horizontal portion of the structural members of the lowest floor is elevated to or above the BFE.

11. ...Elevation Requirements for Zones VE & V1-30... • 2. All new construction shall have the space below the lowest floor free of obstructions or constructed with breakaway walls…

12. No Obstructions

13. Breakaway Walls

14. ...Elevation Requirements for Zones VE & V1-30 • ...Such enclosed space shall not be used for human habitation and will be usable solely for parking of vehicles, building access, or storage.

15. ELEVATED FOUNDATIONS • Fill • Perimeter Wall • Pilings

16. Slab on Fill

17. Criteria for Elevation on Fill • All A Zones, with low-velocity flooding (less than 5 feet per second) • Usually limited to three or four feet in height

18. Standards for Elevation on Fill... • Fill should be placed in maximum 12-inch lifts • Fill should be compacted to 95% of the maximum density obtainable with the Standard Proctor Test Method (ASTM Standard D-698)

19. …Standards for Elevation on Fill • Fill slopes should be no steeper than 1.0-foot vertical to 1.5-feet horizontal • Fill should extend a minimum of 15 feet beyond all sides of the structure • Erosion protection is required

20. Perimeter Wall Foundation Opening (typical))

21. Criteria for Elevation on Perimeter Wall Foundations • All A Zones, with low-velocity flooding (less than 5 feet per second) • Usually limited to three or four feet in height above grade • Enclosed areas below the lowest floor must have openings to equalize hydrostatic pressures

22. Standards for Elevation on Perimeter Wall Foundations... • Fully enclosed areas below the lowest floor shall be designed to automatically equalize hydrostatic flood forces on exterior walls by allowing for the automatic entry and exit of floodwaters…

23. ...Standards for Elevation on Perimeter Wall Foundations • Designs must be certified by a registered engineer or architect, or meet or exceed the minimum opening criteria mentioned earlier

24. Minimum Standards for Foundation Openings... 1) A minimum of two openings on different sides of the enclosed area having a total net area of not less than one square inch for every square foot of enclosed area subject to flooding.

25. ...Minimum Standards for Foundation Openings 2) The bottom of all openings shall be no higher than one foot above grade. 3) Openings may be equipped with screens, louvers, valves, or other “automatic” coverings

26. Pile Foundation

27. Criteria for Pile Foundations • All A and V Zones, with large depths of flooding and high velocities • Particularly well suited for coastal high hazard areas

28. Key Considerations for Pile Foundations • Pile embedment method and depth • Bracing to resist lateral forces • Proper connections (critical in coastal high hazard areas) • Foundation to floor beam • Floor beam to floor joist • Floor joist to wall • Wall to roof

29. Other Elevated Foundation Systems • Shear Walls • Posts • Piers

30. Reminder in V Zones Corrosion protection is needed for foundations built with reinforced concrete or steel I-beams.

31. FEMA Technical Bulletins... • “Openings in Foundation Walls”, FIA-TB-1 April 1993 • “Free of Obstruction Requirements”, FIA-TB-5, April 1993 • “Corrosion Protection for Metal Connectors in Coastal Areas”, FIA-TB-8, August 1996

32. ...FEMA Technical Bulletins • “Design and Construction Guidance for Breakaway Walls Below Elevated Coastal Building”, FIA-TB-9, September 1999

33. Other FEMA Publications • “Elevated Residential Structures”, FEMA-54, March 1984 • “Coastal Construction Manual”, FEMA-55, June 2000 • “Above the Flood: Elevating Your Floodprone House”, FEMA 347, May 2000

35. WET FLOODPROOFING NATIONAL FLOOD INSURANCE PROGRAM

36. Wet Floodproofing Definition • Permanent measures applied to a structure that prevent or provide resistance to damage from flooding by allowing flood waters to enter and exit the structure. • Note: Floodproofing techniques are allowed in A Zones only!

37. When to Use Wet Floodproofing • Enclosed areas below the BFE that are used for parking, building access, or limited storage • Attached garages below the BFE

38. Other Possible Applications of Wet Floodproofing... • If accompanied by a variance, Wet Floodproofing may also be used for the following… • Structures functionally dependent on close proximity to water • Historic structures. . .

39. ...Other Possible Applications of Wet Floodproofing • Some accessory and agricultural structures • Pre-FIRM structures not substantially improved or damaged

40. Wet Floodproofing and Flood Resistant Materials • Flood resistant materials must be used for those areas of a structure below the base flood elevation regardless of the expected or historic flood duration.

41. FEMA Technical Bulletins • “Wet Floodproofing Requirements”, FIA-TB-7, December 1993 • “Flood Resistant Materials Requirements”, FIA-TB-2, April 1993

43. (DRY) FLOODPROOFING • ONLY NON-RESIDENTIAL STRUCTURES MAY BE FLOODPROOFED IN LIEU OF ELEVATION. • Note: Floodproofing is allowed in A Zones only!

44. Dry Floodproofing Definition • Permanent and temporary measures applied to a structure that prevent damage from flooding by making a building watertight, substantially impermeable to floodwaters.

45. “DRY” FLOODPROOFING • Planning requirements • Design • Construction

46. Warning Time Safety and Access Flood Velocities Flood Depths Planning Considerations For Dry Floodproofing...

47. Debris Flood Frequency Emergency Operation Plan Inspection Plan Maintenance Plan ...Planning Considerations For Dry Floodproofing

48. “DRY” FLOODPROOFING DESIGN REQUIREMENTS • The building must be watertight to at least the BFE. • The building’s walls must be “substantially impermeable to the passage of water.” • Have structural components capable of resisting hydrostatic and hydrodynamic loads and effects of buoyancy.

49. MORE DESIGN REQUIREMENTS. . . • Building utilities and sanitary facilities must be located above the BFE, completely enclosed within the building’s watertight walls, or made watertight and capable of resisting damage during flood conditions. • Must be certified by a registered professional engineer or architect.

50. CONSTRUCTION