Chapter 6 Standards for Floodplain Development and Building Protection

Development is…... Construction of new buildings Addition or substantial improvements to existing buildings Manufactured (mobile) homes and RVs Subdivisions or commercial developments Storage of materials Fill, grading, excavating Fences, culverts, bridges, roads And ANYTHING else that changes the floodplain

Standards of Floodplain Development Federal regulations at Subpart B, Section (a)(3) require that communities adopt the minimum provisions of 44 CFR These standards must be applied to all development and structures built or substantially improved in the SFHA.

Elevation on Fill Elevation on flow-thru walls Elevation by poles, piers, or columns Methods to Elevate Buildings in an A Zone Building Protection Standards

Building Protection Standards Elevation on Fill Fill

Before allowing floodplain fill, decide if the fill will increase flooding or cause drainage problems on neighboring properties. Elevation on Fill Building Protection Standards Elevation on Fill (cont.)

Before permitting floodplain fill, decide if the applicant plans to excavate a basement into the fill. Basements are not allowed in the SFHA! Elevation on Fill Building Protection Standards Elevation on Fill (cont.) What is a basement?

Building Protection Standards Elevation on Fill (cont.) Usually limited to three or four feet in height Usually limited to three or four feet in height Fill placed in 6’ layers and compacted (95% proctor) Fill placed in 6’ layers and compacted (95% proctor) Extend fill 10’ around structure Extend fill 10’ around structure Side slopes 1’ vertical to 1.5’ horizontal Side slopes 1’ vertical to 1.5’ horizontal Erosion control Erosion control

House built on fill above the flood elevation Building Protection Standards Elevation on Fill (cont.)

Building Protection Standards Elevation on Solid Perimeter Walls Opening (typical)

Types of solid wall foundations: Chain walls Perimeter walls Unreinforced masonary block Unreinforced brick Some types are required to have flood vents Building Protection Standards Elevation on Solid Perimeter Walls (cont.)

Building Protection Standards Elevation on Solid Perimeter Walls (Cont.) Enclosed areas below the lowest floor must have openings to equalize hydrostatic pressures (1” per 1 sq. ft.). Enclosed areas below the lowest floor must have openings to equalize hydrostatic pressures (1” per 1 sq. ft.). Openings no more than one foot above grade. Openings no more than one foot above grade. Flood resistant materials Flood resistant materials NO HVAC, electric, utilities, etc.. NO HVAC, electric, utilities, etc..

Building Protection Standards Elevation on Solid Perimeter Walls (cont.) Use of Enclosed Areas below the BFE Parking Limited Storage Building Access

Building Protection Standards Elevation on Solid Perimeter Walls (cont.) Flood-Resistant Materials All materials below the BFE must be resistant to water damage. TB 2-93 is the best source of information.

TB 1-93 Building Protection Standards Elevation on Solid Perimeter Walls (cont.)

House built on elevated foundation walls Flow through crawl space

Building Protection Standards Special Notes About Basements Definition of a basement? Can a crawl space be defined as a basement? A “walk-out” basement is an enclosure below the BFE. What does that mean?

What do you notice about the vents?

Good vents?

Example: In an area with a BFE of 6 ft, fill could be placed for 3 ft and chain wall or crawl space built for the additional 3 ft (plus any freeboard). Building Protection Standards Elevation on Fill (cont.) Or, a combo of slab and raised floor.

Building Protection Standards Elevation on Posts or Piles

Posts or columns are wood, steel, concrete, or masonry supports. Piers are vertical structural members supported by concrete footings. Piles are generally made of wood or prestressed concrete. Elevation on Post, Columns, Piers or Piles Building Protection Standards Elevation on Posts or Piles (cont.)

Piles Building Protection Standards Elevation on Posts or Piles (cont.)

Piers Posts

Building Protection Standards Elevation on Posts or Piles (cont.) Should be used in areas of deep flooding and/or high velocities (floodways) Should be used in areas of deep flooding and/or high velocities (floodways) Properly anchored to resist wind and water forces Properly anchored to resist wind and water forces Lower area must remain open (not enclosed later) Lower area must remain open (not enclosed later)

House built on piers or poles above the flood elevation

Building Protection Standards Crawlspace Total height no more than 4 feet. Total height no more than 4 feet. No more than 2’ below grade. No more than 2’ below grade. Flow through openings Flow through openings Interior drainage controls Interior drainage controls Flood resistant materials Flood resistant materials Technical Bulletin 11-01

NOT in the Gulf States. Not while I’ve got a say!

Mean High Tide: All new construction in V Zones must be located landward of the reach of mean high tide. Modification of Dunes: Prohibit man-made alteration of sand dunes in V Zones. Building Protection Standards Coastal High Hazard or V Zone Construction

Building Protection Standards Coastal High Hazard or V Zone Construction (cont.) Methods to Elevate Buildings in a V Zone New and substantially improved structures must have the bottom of the lowest horizontal member at or above the BFE.

Building Protection Standards Coastal High Hazard or V Zone Construction (cont.) Bottom of the lowest horizontal structural member supporting the lowest floor Bottom of the lowest horizontal structural member supporting the lowest floor

Building Protection Standards Coastal High Hazard or V Zone Construction (cont.) Methods to Elevate Buildings in a V Zone A certificate of the design foundations for buildings in V zones is required to be submitted prior to permit issuance.

Structural Fill is prohibited to support buildings. Nonstructural fill, such as might be used for landscaping, should be placed so that it does not divert waves and surging floodwaters onto other structures. Coastal High Hazard Areas or V Zones Building Protection Standards Coastal High Hazard or V Zone Construction (cont.)

FEMA Technical Reference

Building Protection Standards Coastal High Hazard or V Zone Construction (cont.) Connecting the Load Path in the V Zone Continuous path from roof to wall to foundation Materials that resist deterioration

Building Protection Standards Coastal High Hazard or V Zone Construction (cont.) In V Zones, the applicant must include the V Zone Certificate and an engineer’s certification of design on a breakaway wall. V Zone / Breakaway Wall Certificate

Building Protection Standards Coastal High Hazard or V Zone Construction (cont.) Breakaway Walls (V Zone) Minimum standard requires collapse after not less than 10 and no more than 20 pounds per square foot.

35 Pre-Event

Post-Event

Building Protection Standards Coastal High Hazard or V Zone Construction (cont.) Your flood damage prevention ordinance prohibits manmade alterations of sand dunes that will increase potential flood damage. Altering Sand Dunes CoBRA NFIP insurance not available. You must still review and issue permits.

Permit Issuance (continued) Fill is not allowed as a method to elevate buildings in V Zones. FEMA does not allow placement of fill in V Zones as a method to remove a site from the mapped floodplain by means of a LOMR-F. Non-structural fill may be used for landscaping purposes and cannot divert waves and water toward any building. V Zones and Fill

Building Protection Standards Manufactured Homes Manufactured Homes Manufactured homes are treated the same as any other structure in the SFHA. Make it easy, require all units to be at or above the BFE!

Building Protection Standards Manufactured Homes (cont.) Manufactured Homes are extremely vulnerable to flood damage. You may wish to require that a engineered foundation to ensure structural stability. Anchoring, tie-down, & permanent foundation requirements must be outlined in the FP permit. Special Considerations

FEMA 85 Sept. 1985

Building Protection Standards Non-Residential Floodproofing ONLY NON- RESIDENTIAL STRUCTURES MAY BE FLOODPROOFED IN LIEU OF ELEVATION. ONLY NON- RESIDENTIAL STRUCTURES MAY BE FLOODPROOFED IN LIEU OF ELEVATION.

Building Protection Standards Non-Residential Floodproofing (cont.) 1. Non-residential construction may be floodproofed below the BFE so that the structure is watertight with walls substantially impermeable to the passage of water. 1. Non-residential construction may be floodproofed below the BFE so that the structure is watertight with walls substantially impermeable to the passage of water. 2. Have structural components capable of resisting hydrostatic and hydrodynamic loads and effects of buoyancy. 2. Have structural components capable of resisting hydrostatic and hydrodynamic loads and effects of buoyancy.

Building Protection Standards Non-Residential Floodproofing (cont.) A Floodproofing Certificate is required for all floodproofed structures A Floodproofing Certificate is required for all floodproofed structures The Floodproofing Certificate must be signed by an Engineer The Floodproofing Certificate must be signed by an Engineer The form can be obtained at: The form can be obtained at:

Building Protection Standards Wet Floodproofing / Minor Accessory Structures “Permanent or contingent measures applied to a structure and/or its contents that prevent or provide resistance to damage from flooding by allowing flood waters to enter the structure.” “Permanent or contingent measures applied to a structure and/or its contents that prevent or provide resistance to damage from flooding by allowing flood waters to enter the structure.”

When to Use Wet Floodproofing Enclosed areas below the BFE that are used for parking, building access, or limited storage Enclosed areas below the BFE that are used for parking, building access, or limited storage Attached or detached garages Attached or detached garages Minimal value storage sheds and garages Minimal value storage sheds and garages Building Protection Standards Wet Floodproofing / Minor Accessory Structures

Building Protection Standards Wet Floodproofing / Minor Accessory Structures  Non-habitable  Anchored  Openings  No HVAC or electric  Used only for storage  No later modification  Flood resistant materials  Document elevation  Size and/or cost threshold Standards for wet floodproofing:

Building Protection Standards Wet Floodproofing / Minor Accessory Structures FPE Openings to allow floodwaters to flow in & out

Building Protection Standards Wet Floodproofing / Minor Accessory Structures Agricultural Structures May be elevated or; Wet floodproofed under certain conditions with a variance. Call State NFIP Coordinator if you plan to use a variance.

Building Protection Standards Wet Floodproofing / Minor Accessory Structures Agricultural Structures: Variance Procedures Use limited to agricultural purposes; Flood-resistant materials below the BFE; Anchored and impact resistant; Hydrostatic venting is required; Mechanical, electrical, or other utilities either above the BFE or floodproofed; Floodway encroachments cannot be waived; and, Major equipment or contents must be evacuated prior to a flood.

Building Protection Standards Wet Floodproofing / Minor Accessory Structures Temporary Structures Common examples are: Construction trailers; Portable bathroom facilities; Large trash receptacles; and, Roadside stands.

Temporary Structures

Building Protection Standards RVs and Travel Trailers 1. Self propelled or towable by a light duty truck 2.No porch or deck 3.No permanent dwelling. Only seasonal use. 4.No more than 400 sq. ft. 5.Wheels on axles and inflated 6.Quick disconnect utilities 7.Licensed and titled as an RV 8.Supported by wheels or jacks. No blocks.

If an RV is on-site for more than 180 days, it must: Building Protection Standards RVs and Travel Trailers

Utility Service in Buildings: Plumbing, mechanical, heating, A/C, toilets, sinks, showers, water heaters, furnaces, heat pumps, generators, air distribution systems, and other permanent plumbing, mechanical, and electrical installations must be elevated to or above the flood protection elevation. Building Protection Standards Utilities and tanks

Utilities Elevate me ! 125

Utilities Power Outlet Vented area below elevated floor. Base Flood Elevation

Duct work must be elevated above the BFE. Building Protection Standards Utilities and tanks

Storage Tanks Above ground tanks may be anchored or elevated up to 5-feet from grade. Below ground tanks must be anchored, require engineered installation.

Above ground tanks

Private On-Site Utilities: On site waste disposal systems such as septic tanks and septic fields should be protected. How? Protecting Utilities Building Protection Standards Utilities and tanks Backflow valves, watertight enclosures, and platforms above the BFE.

Standards of Floodplain Development Functionally Dependent Use May only be approved by a variance. Does not relieve the applicant or community of responsibility to reduce damage potential.

Building Protection Standards Substantial Improvement Any combination of alteration or improvement to a building taking place (during the life of the structure or a 10-year period), in which the cumulative percentage of improvements equals or exceeds 50% of the current market value of the structure.

Building Protection Standards Substantial Improvement Compliance When the 50% rule is evoked, the original residential building must be elevated. Non-residential buildings can be floodproofed, with the proper certifications.

Existing House FPE Original Ground

Substantial Improvement Existing House + Garage/FR/BR Addition FPE Original Ground Added Fill Raise Existing House & Build Addition above FPE

Building Protection Standards Substantial Improvement Horizontal or Lateral Additions Only the addition must meet lowest floor requirements, if the structure is Pre-FIRM and the cost is less than 50% of the market value.

Building Protection Standards Substantial Improvement Horizontal Additions If the structure is Pre-FIRM and the cost is more than 50% of the market value, the entire structure must be raised to or above the BFE.

Existing Pre-FIRM Residential Structure FPE After Substantial Improvement Vertical Addition Compliant With NFIP Criteria (Zone A) AC Utility Box Elevate on fill or crawl required BEFORE AFTER

Building Protection Standards Substantial Improvement Vertical Additions Second-story additions almost always trigger the 50% rule.

Building Protection Standards Substantial Improvement Determining Building Value Building value is the market value of the building prior to the damage or improvement. You can require a professional appraisal. Tax assessor records can be used as a screening tool only. Apply your approach consistently!

The formula Cost of improvement project > 50% Market value of the building _____________ $140,000 house $75,000 project = 54% Building Protection Standards Substantial Improvement

Substantial Improvement tracking (one example)

Subdivisions Building Protection Standards Subdivisions and large developments

Subdivisions: Open Space Design Building Protection Standards Subdivisions and large developments

NFIP Technical Bulletins TB 1-93 Openings in Foundation Walls TB 2-93 Flood-Resistant Material Requirements TB 3-93 Non-Residential Floodproofing TB 4-93 Elevator Installation TB 5-93 Free of Obstruction Requirements in V Zone TB 6-93 Below Grade Parking Requirements TB 7-93 Wet Floodproofing Requirements TB 8-06 Corrosion Protection for Metal Connectors TB 9-99 Breakaway Walls TB Structures Built on Fill