Chapter 6 Standards for Floodplain Development and Building Protection

Chapter 6Chapter 6Standards for Floodplain Standards for Floodplain Development and Building Development and Building ProtectionProtection

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 DevelopmentStandards of Floodplain Development

Federal regulations at Subpart B, Section 59.22 (a)(3) require that communities adopt the minimum provisions of 44 CFR 60.3.

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 Building Protection Standards Building Protection Standards

Building Protection StandardsBuilding Protection Standards Elevation on FillElevation on FillBuilding Protection StandardsBuilding Protection Standards Elevation on FillElevation 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.)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 Building Protection Standards Elevation on Fill (cont.)Elevation on Fill (cont.)Building Protection Standards Building Protection Standards Elevation on Fill (cont.)Elevation on Fill (cont.)

What is a basement?

Building Protection Standards Elevation on Fill (cont.)Building Protection Standards Elevation on Fill (cont.)

• Usually limited to three or four feet in heightUsually 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 structureExtend fill 10’ around structure

• Side slopes 1’ vertical to 1.5’ horizontalSide slopes 1’ vertical to 1.5’ horizontal

• Erosion controlErosion control

House built on fill above the flood elevation

Building Protection Standards

Elevation on Fill (cont.)

Building Protection StandardsBuilding Protection Standards Elevation on Solid Perimeter WallsElevation on Solid Perimeter WallsBuilding Protection StandardsBuilding Protection Standards Elevation on Solid Perimeter WallsElevation 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 StandardsBuilding Protection Standards Elevation Elevation on Solid Perimeter Walls (cont.)on Solid Perimeter Walls (cont.)Building Protection StandardsBuilding Protection Standards Elevation Elevation on Solid Perimeter Walls (cont.)on Solid Perimeter Walls (cont.)

Building Protection StandardsBuilding Protection Standards Elevation Elevation on Solid Perimeter Walls (Cont.)on Solid Perimeter Walls (Cont.)Building Protection StandardsBuilding Protection Standards Elevation Elevation on Solid Perimeter Walls (Cont.)on Solid Perimeter Walls (Cont.)

• Enclosed areas below the lowest floor Enclosed areas below the lowest floor must have openings to equalize must have openings to equalize hydrostatic pressures (1” per 1 sq. ft.). hydrostatic pressures (1” per 1 sq. ft.).

• Openings no more than one foot above Openings no more than one foot above grade.grade.

• Flood resistant materialsFlood resistant materials

• NO HVAC, electric, utilities, etc..NO HVAC, electric, utilities, etc..

Building Protection StandardsBuilding Protection Standards Elevation on Solid Perimeter Walls (cont.)Elevation on Solid Perimeter Walls (cont.)Building Protection StandardsBuilding Protection Standards Elevation on Solid Perimeter Walls (cont.)Elevation on Solid Perimeter Walls (cont.)

Use of Enclosed Areas below the BFE

• Parking• Limited

Storage• Building

Access

Building Protection StandardsBuilding Protection Standards Elevation on Solid Perimeter Walls (cont.)Elevation on Solid Perimeter Walls (cont.)Building Protection StandardsBuilding Protection Standards Elevation on Solid Perimeter Walls (cont.)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 StandardsBuilding Protection Standards

Elevation on Solid Perimeter Walls (cont.)Elevation on Solid Perimeter Walls (cont.)

House built on elevated foundation walls

Flow through crawl space

Building Protection StandardsBuilding Protection StandardsBuilding Protection StandardsBuilding 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 StandardsBuilding Protection Standards Elevation on Fill (cont.)Elevation on Fill (cont.)Building Protection StandardsBuilding Protection Standards Elevation on Fill (cont.)Elevation on Fill (cont.)

Or, a combo of slab andraised floor.

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

Piles


Elevation on Posts or Piles (cont.)Elevation on Posts or Piles (cont.)

Piers

Posts

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

• Should be used in areas of deep Should be used in areas of deep flooding and/or high velocities flooding and/or high velocities (floodways)(floodways)

• Properly anchored to resist wind and Properly anchored to resist wind and water forceswater forces

• Lower area must remain open (not Lower area must remain open (not enclosed later)enclosed later)

House built on piers or poles above the flood elevation

Building Protection StandardsBuilding Protection Standards CrawlspaceCrawlspace

• Total height no more Total height no more than 4 feet.than 4 feet.

• No more than 2’ below No more than 2’ below grade.grade.

• Flow through openingsFlow through openings

• Interior drainage Interior drainage controlscontrols

• Flood resistant materialsFlood resistant materials Technical Bulletin 11-Technical Bulletin 11-0101

NOT in the Gulf States. NOT in the Gulf States.

Not while I’ve got a say!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 StandardsBuilding Protection Standards Coastal High Hazard or V Zone ConstructionCoastal High Hazard or V Zone ConstructionBuilding Protection StandardsBuilding Protection Standards Coastal High Hazard or V Zone ConstructionCoastal High Hazard or V Zone Construction

Building Protection StandardsBuilding Protection Standards Coastal Coastal High Hazard or V Zone Construction (cont.)High Hazard or V Zone Construction (cont.)Building Protection StandardsBuilding Protection Standards Coastal Coastal High Hazard or V Zone Construction (cont.)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 StandardsBuilding Protection Standards Coastal Coastal High Hazard or V Zone Construction (cont.)High Hazard or V Zone Construction (cont.)

Bottom of Bottom of the lowest the lowest horizontal horizontal structural structural member member supporting supporting the lowest the lowest floorfloor

Building Protection StandardsBuilding Protection Standards Coastal High Hazard or V Zone Construction Coastal High Hazard or V Zone Construction

(cont.)(cont.)

Building Protection StandardsBuilding Protection Standards Coastal High Hazard or V Zone Construction Coastal High Hazard or V Zone Construction

(cont.)(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


FEM

A T

ech

nica

l Refe

rence

FEM

A T

ech

nica

l Refe

rence


Connecting the Load Path in the V Zone

• Continuous path from roof to wall to foundation• Materials that resist deterioration


• 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


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


• 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 Permit Issuance (continued)(continued)

Permit Issuance Permit Issuance (continued)(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 StandardsBuilding Protection Standards Manufactured HomesManufactured HomesBuilding Protection StandardsBuilding Protection Standards Manufactured HomesManufactured Homes

Manufactured Homes

• Manufactured homes are treated the same as any other structure in the SFHA.

Make it easy, require all unitsto be at or above the BFE!

Building Protection StandardsBuilding Protection Standards Manufactured Homes (cont.)Manufactured Homes (cont.)Building Protection StandardsBuilding Protection Standards Manufactured Homes (cont.)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 85Sept. 1985

Building Protection StandardsBuilding Protection Standards Non- Non-Residential FloodproofingResidential FloodproofingBuilding Protection StandardsBuilding Protection Standards Non- Non-Residential FloodproofingResidential Floodproofing

ONLY NON-ONLY NON-RESIDENTIAL RESIDENTIAL STRUCTURES MAY STRUCTURES MAY BE BE FLOODPROOFED IN FLOODPROOFED IN LIEU OF LIEU OF ELEVATION.ELEVATION.

Building Protection StandardsBuilding Protection Standards Non- Non-Residential Floodproofing (cont.)Residential Floodproofing (cont.)Building Protection StandardsBuilding Protection Standards Non- Non-Residential Floodproofing (cont.)Residential Floodproofing (cont.)

1. Non-residential construction may be 1. Non-residential construction may be floodproofed below the BFE so that the floodproofed below the BFE so that the structure is watertight with walls structure is watertight with walls substantially impermeable to the passage substantially impermeable to the passage of water.of water.

2. Have structural components capable of 2. Have structural components capable of resisting hydrostatic and hydrodynamic resisting hydrostatic and hydrodynamic loads and effects of buoyancy.loads and effects of buoyancy.

Building Protection StandardsBuilding Protection Standards Non- Non-Residential Floodproofing (cont.)Residential Floodproofing (cont.)

• A Floodproofing Certificate is required for A Floodproofing Certificate is required for all floodproofed structuresall floodproofed structures

• The Floodproofing Certificate must be The Floodproofing Certificate must be signed by an Engineersigned by an Engineer

• The form can be obtained at: The form can be obtained at: www.FEMA.gov/library/floodproofwww.FEMA.gov/library/floodproof

Building Protection StandardsBuilding Protection Standards Wet Wet Floodproofing / Minor Accessory Structures Floodproofing / Minor Accessory Structures Building Protection StandardsBuilding Protection Standards Wet Wet Floodproofing / Minor Accessory Structures Floodproofing / Minor Accessory Structures

““Permanent or Permanent or contingent measures contingent measures applied to a structure applied to a structure and/or its contents and/or its contents that prevent or that prevent or provide resistance to provide resistance to damage from damage from flooding by allowing flooding by allowing flood waters to enter flood waters to enter the structure.”the structure.”

When to Use Wet FloodproofingWhen to Use Wet FloodproofingWhen to Use Wet FloodproofingWhen to Use Wet Floodproofing

• Enclosed areas below the BFE that Enclosed areas below the BFE that are used for parking, building access, are used for parking, building access, or limited storageor limited storage

• Attached or detached garagesAttached or detached garages

• Minimal value storage sheds and Minimal value storage sheds and garagesgarages


Wet Floodproofing / Minor Accessory StructuresWet Floodproofing / Minor Accessory Structures

Building Protection StandardsBuilding Protection Standards Wet Wet Floodproofing / Minor Accessory StructuresFloodproofing / Minor Accessory StructuresBuilding Protection StandardsBuilding Protection Standards Wet Wet Floodproofing / Minor Accessory StructuresFloodproofing / Minor Accessory Structures

Non-habitableNon-habitable AnchoredAnchored OpeningsOpenings No HVAC or electricNo HVAC or electric Used only for storageUsed only for storage No later modificationNo later modification Flood resistant materialsFlood resistant materials Document elevationDocument elevation Size and/or cost Size and/or cost

thresholdthreshold

Standards for wet floodproofing:

Building Protection StandardsBuilding Protection Standards Wet Wet Floodproofing / Minor Accessory StructuresFloodproofing / Minor Accessory Structures

FPE

Openings to allow Openings to allow floodwaters to floodwaters to flow in & outflow in & out

Building Protection StandardsBuilding Protection StandardsWet Floodproofing / Minor Accessory StructuresWet Floodproofing / Minor Accessory StructuresBuilding Protection StandardsBuilding Protection StandardsWet Floodproofing / Minor Accessory StructuresWet 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 StandardsBuilding Protection StandardsWet Floodproofing / Minor Accessory StructuresWet Floodproofing / Minor Accessory StructuresBuilding Protection StandardsBuilding Protection StandardsWet Floodproofing / Minor Accessory StructuresWet 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 StandardsBuilding Protection Standards Wet Wet Floodproofing / Minor Accessory StructuresFloodproofing / Minor Accessory StructuresBuilding Protection StandardsBuilding Protection Standards Wet Wet Floodproofing / Minor Accessory StructuresFloodproofing / Minor Accessory Structures

Temporary Structures

• Common examples are:• Construction trailers;• Portable bathroom facilities;• Large trash receptacles; and,• Roadside stands.

Temporary Structures


RVs and Travel TrailersRVs 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-If an RV is on-site for more site for more than 180 days, it than 180 days, it must:must:

Building Protection Standards Building Protection Standards RVs and Travel TrailersRVs 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 StandardsBuilding Protection Standards Utilities and tanksUtilities and tanksBuilding Protection StandardsBuilding Protection Standards Utilities and tanksUtilities 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.



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


• Backflow valves, watertight enclosures, and platforms above the BFE.

Standards of Floodplain Standards of Floodplain DevelopmentDevelopmentStandards of Floodplain Standards of Floodplain DevelopmentDevelopment

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 StandardsBuilding Protection Standards Substantial ImprovementSubstantial ImprovementBuilding Protection StandardsBuilding Protection Standards Substantial ImprovementSubstantial 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.


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 HouseExisting House

FPE

Original Ground

Substantial Improvement Substantial Improvement Existing House + Garage/FR/BR AdditionExisting House + Garage/FR/BR Addition

FPE

Original Ground

Added Fill

•Raise Existing House & Build Addition above FPE


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.


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 Existing Pre-FIRM Residential StructureResidential Structure

FPE FPE

After Substantial ImprovementAfter Substantial Improvement

Vertical AdditionVertical AdditionCompliant With Compliant With NFIP Criteria (Zone A)NFIP Criteria (Zone A)

AC

AC

UtilityBox

Elevate on fill or crawl required

BEFOREBEFORE

AFTERAFTER


Vertical Additions

• Second-story additions almost always trigger the 50% rule.


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 formulaThe formula

Cost of improvement project Cost of improvement project >> 50% Market value of the building50% Market value of the building

__________________________$140,000 house$140,000 house

$75,000 project = 54%

Building Protection StandardsBuilding Protection Standards Substantial Substantial ImprovementImprovementBuilding Protection StandardsBuilding Protection Standards Substantial Substantial ImprovementImprovement


Substantial Improvement tracking (one example)

• Subdivisions

Building Protection StandardsBuilding Protection Standards Subdivisions and large developmentsSubdivisions and large developmentsBuilding Protection StandardsBuilding Protection Standards Subdivisions and large developmentsSubdivisions and large developments

• Subdivisions: Open Space Design

Building Protection StandardsBuilding Protection Standards Subdivisions and large developmentsSubdivisions and large developmentsBuilding Protection StandardsBuilding Protection Standards Subdivisions and large developmentsSubdivisions and large developments

NFIP Technical BulletinsNFIP Technical BulletinsNFIP Technical BulletinsNFIP 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 10-01 Structures Built on Fill

Documents

Chapter 6 Standards for Floodplain Development and Building Protection