Comments Submitted by the ASCE 7 Flood Load Technical Committee in response to the
FEMA Public Comment Period on the National Flood Insurance Program’s Minimum
Floodplain Management Standards.
Member
Location
Company
Andre Barbosa, P.E., Ph.D
Graham Brasic P.E., S.E.
Chris Cerino, P.E.
Bill Coulbourne, P.E.
Dan Cox (chair), Ph.D.
Matthew Gilbertson, P.E., S.E.
Carol Friedland Ph.D., P.E.
Tori Johnson, Ph.D.
Chris Jones, P.E.
Richard Lo, P.E.
Jessica Mandrick, P.E., S.E.
Jeff Melby Ph.D.
Mehedi Rashid, P.E., S.E.
Seth Thomas, P.E., S.E.
Peter Willse, P.E.
OR
FL
NY
MD
OR
OR
LA
MD
NC
TX
NY
MS
MD
OR
CT
Oregon State University
Jezerinac Group
STV Inc.
Coulbourne Consulting
Oregon State University
Simpson Gumpertz and Heger
Louisiana State University
US Naval Academy
Consulting
Langan Engineering
Gilsanz Murray Steficek
USACE
Moffatt & Nichol
KPFF Consulting
Willse Engineering
The American Society of Civil Engineers Standard ASCE/SEI 7-22 Minimum Design Loads for
Buildings and Other Structures incorporates a chapter on flood loading, Chapter 5. The ASCE 7
Flood Load Technical Committee is responsible for this chapter and is currently working on a
supplement which will propose determining flood loads based on flood mean recurrence
intervals (MRI) that are higher than the National Flood Insurance Program (NFIP) 100-year
standard for most building structures.
Our committee has found that the flood loads presently derived from the Base Flood (i.e., 100year flood or 1% annual probability of exceedance flood), do not meet the reliability targets of
the ASCE 7 standard. Wind events, which often occur concurrently with coastal floods, utilize
mean recurrence intervals of 300, 700, 1700, and 3000-years for Risk Category I-IV structures
respectively. The loads resulting from 100-year flood events are not proportional to the wind
events that are at these higher recurrence intervals. Previous editions of ASCE 7 have tried to
increase the reliability by applying a load factor of two on flood loads in coastal regions subject
to wave action. This scaling factor increased the magnitude of the flood loads for structures
within coastal high hazard areas but did not increase the depth over which the load was applied
or the geographic area where the flood load would be considered. This reduced the effectiveness
of the load factor approach.
Our committee is proposing a supplement to ASCE 7 to increase the geographic area subject to
flood provisions of the standard from the 100-year floodplain to the 500-year floodplain. We also
propose utilizing MRI flood elevations corresponding to the importance of a structure: a 100year MRI flood elevation would be used for Risk Category I Structures (structures with a low
risk to human life in the event of failure); a 500-year MRI flood elevation for Risk Category II
Structures (most residential and commercial structures); and a 750-year and 1,000-year MRI
flood elevation for Risk Category III and IV Structures, respectively (critical structures with the
highest risk to human life in the event of failure). In accordance with these proposals, we believe
that the 100-year flood is not an appropriate basis for the design for most structures.
As only loading is within the purview of this standard, we are providing the loading based on the
flood elevation and cannot mandate building floor elevations or construction standards. We
encourage FEMA to adopt the following:
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utilize a risk-based approach to floodplain management standards;
utilize the 500-year flood as the basis for design of Risk Category II buildings and set
building elevation requirements above the 500-year flood elevation;
utilize floods higher than the 500-year flood for Risk Category III and IV essential and
critical buildings;
utilize the 500-year floodplain as the regulatory flood hazard area;
incorporate future conditions, such as climate change effects, into regulatory floodplain
designations and building standards;
utilize the 500-year flood as the basis of design for single and multi-family homes built
in accordance with the International Residential Code (IRC). The IRC does not adopt
ASCE 7 for loads. Single family homes and other IRC structures suffer large flood
related losses, and increasing the MRI flood for these structures will reduce those losses.
We appreciate FEMA’s willingness to accept public comments on the National Flood Insurance
Program’s Minimum Floodplain Management Standards, and we look forward to developing
consistencies between ASCE’s minimum standards for flood loads and FEMA’s minimum
requirements for floodplain management to minimize flood damage and loss.