Higher Standards: When Paying a Bit More Costs a Lot Less February 14, 2013

Eric D. Kenney, P.E., CFM

Georgia Association of Floodplain Management

Higher Standard (ASCE 24-05)

Technical Provisions of the Higher Standard

Comparison to Existing Standards and Current Uses

Implementation Benefits

Implementation Issues

Summary

Overview

ASCE 24-05 Standard

National consensus standard for flood resistant

design and construction developed by

ASCE/SEI.

Improved design and construction standards

identified through the consensus process to

address damage to new buildings constructed

consistent with NFIP requirements.

Second edition published in 2006 and the next

revision cycle is in progress.

ASCE 24-05 can be used for new construction,

as well as to guide repairs of existing buildings.

ASCE 24-05 directs design and construction

based on structure classification (criticality and

nature of occupancy) and based on flood

hazard classification.

Structure Category

Category Description

I Low hazard to human life in the event of a failure: includes agriculture facilities

and storage facilities.

II Encompasses all structure types except those specifically listed in Category I, III,

and IV; includes single- and multi-family residences.

III Represents a substantial hazard to human life in the event of a failure; includes

schools, colleges, healthcare facilities, and other structures where large numbers

of people congregate.

IV Essential facilities; includes fire stations and other emergency services (including

hospitals), as well as other critical infrastructure-type facilities (i.e., power

generation, aviation control, etc.).

ASCE – Flood Resistant Design and Construction (ASCE/SEI 24-05), 2006

ASCE – Flood Resistant Design and Construction (ASCE/SEI 24-05), 2006

Combining Flood Hazard and Structure Criticality

NFIP I II III IV

Elevation of Lowest

Floor

(A Zone)

A Zones not identified

as Coastal A Zones:

elevation of lowest

floor

DFE or

above

(based

on food

zone)

DFE BFE +1 ft

or DFE

BFE +1 ft

or DFE

BFE +2 ft

or DFE

Elevation of Lowest

Floor or Bottom of

Lowest Horizontal

Structural Member

(V Zone)

V Zones and Coastal

A Zones:

(lowest parallel

member)

DFE DFE BFE +1 ft

or DFE

BFE +1 ft

or DFE

V Zones and Coastal

A Zones:

(lowest perpendicular

member)

DFE BFE +1 ft

or DFE

BFE +2 ft

or DFE

BFE +2 ft

or DFE

Managing Flood Risk

Area Applicability

Flood Risk

Riverine AE, AH, AO Specific guidance on methods, materials, and

elevation requirements.

Coastal A, V Specific guidance on methods, materials, and

elevation requirements.

Decertified Flood

Protection System (AR)

Siting requirements (DFE determination

needed).

Hazard Risk Not

Identified

Siting requirements (DFE determination

needed).

Technical Applicability of ASCE 24-05: by Project Type

Area HMA NFIP

Project

Type

Structure Elevation Additional Requirements Additional Requirements

Dry Floodproofing Additional Requirements Additional Requirements

Mitigation

Reconstruction Generally Consistent Generally Consistent

Higher Standards and FEMA HMA Guidance

Project Type Use in FEMA Funded Projects

Structure Elevation Encouraged

Mitigation Reconstruction

Required

Dependent on flood hazard;

International Residential Code -

IRC 2006 for 1- and 2-family

dwellings; IBC 2006 for multi-

family dwellings)

Encouraged

(IBC 2009)

Dry Floodproofing - Historical

Residential / Non-Residential

Encouraged

Current Standards

Criteria NFIP Community Rating System (CRS) 24-05

Elevation BFE 100 Points for each foot of freeboard (deductions if utilities

are not included)

BFE / DFE may

require additional

freeboard (including

utilities).

Foundation No

specifics

35 Points – P.E. Certified or Fill Elevation is above BFE

(including beyond building limits)

Detailed foundation

requirements,

including elevation.

Critical

Facilities BFE

100 Points – Outside the 500-yr Flood Plain (new)

50 Points – Protected from 500-yr flood (new/substantially

improved)

BFE + 2 or DFE

Current Standards

Criteria NFIP CRS 24-05

Enclosures Below

the BFE

Vents /

Hydrostatic

Equilibrium

None allowed (300 pts)

None larger than 300 sq. ft (100 pts)

Non-conversion agreement with owner (50 pts)

DFE - Parking /

Storage Only w/

Flow Through

Requirements

Building Codes

NFIP Minimums

and

Enforcement

Adopting International Building Code, including ASCE 24,

and obtaining BC Effectiveness Grade above 7 (15 pts for

each grade above 7)

Adopting full IBC (100 pts) (190 Max)

-

Coastal A Zones A Zone

Requirements

Meet V Zone building requirements and A Zone opening

requirements (500)

No enclosures below BFE (150)

Section 4

(Coastal High

Hazard Areas

and Coastal A

Zones)

Implementation Considerations – Increased Cost

Flood Zone Freeboard (ft)

Cost of Freeboard

(% Increase)

Average Premium

Savings as a Percent

of Total Cost of

Construction

Average Payback

Period for Additional

Cost of Freeboard

(Years)

V Zone

BFE +1 0.4 – 1.8

0.45

2.0

BFE +2 0.8 – 3.6 0.87 2.5

BFE +3 1.3 - 5.4 1.09 2.7

BFE +4 1.7 – 7.2 1.19 3.1

Coastal A

Zone

BFE +1 0.5 – 3.9

0.18

4.4

BFE +2 0.7 – 4.8 0.24 6.0

BFE +3 1.1 – 6.1 0.26 7.9

BFE +4 1.4 – 8.1 0.25 9.6

A Zone

BFE +1 0.2 – 2.3

0.20

3.3

BFE +2 0.3 – 4.5 0.26 4.6

BFE +3 0.7 – 6.8 0.28 6.4

BFE +4 0.9 – 9.1 0.27 8.2

Jones, C.P, et al. Evaluation of the NFIP’s Building Standard, 2006

Implementation Considerations – Insurance Savings

V Zone A Zone

Freeboard Annual Savings 30-Year Savings Annual Savings 30-Year Savings

1’ Freeboard $1,360 (25%) $40,800 $502 (41%) $15,060

2’ Freeboard $2,730 (50%) $81,900 $678 (55%) $20,340

3’ Freeboard $3,415 (62%) $102,450 $743 (60%) $22,290

NFIP premiums are based on May 2007 rates for one-floor residential structures with no basement, built

after a FIRM was issued for the community (post-FIRM rates differ from pre-FIRM rates). The coverage

and deductibles are as follows: $500 Deductible/$250,000 Coverage for Building and $100,000

Coverage for Contents.

Jones, C.P, et al. Evaluation of the NFIP’s Building Standard, 2006

Implementation Considerations

• Higher Technical Standard

– Increased design requirements

– Requires better understanding of flood hazards

– Increased professional verification requirements

– But, increased survivability of structures

• Higher Initial Construction Costs

– Elevation projects – directly related to freeboard

– But, potential for reduced premiums, and decreased flood damages

QUESTIONS?