R322.1.3 Flood-resistant construction.
Buildings and structures erected in areas prone to flooding shall be constructed by methods and practices that minimize flood damage.
The intent of the code is to minimize damage resulting from flooding. While a laudable goal, minimizing damage falls short of the typical intent of most code which is to eliminate damage. An immutable fact is that resisting a flood, as the title of the code section implies, requires enormous hubris.
R322.1.4 Establishing the design flood elevation.
The design flood elevation shall be used to define flood hazard areas. At a minimum, the design flood elevation shall be the higher of the following:
1. The base flood elevation at the depth of peak elevation of flooding, including wave height, that has a 1-percent (100-year flood) or greater chance of being equaled or exceeded in any given year.
2. The elevation of the design flood associated with the area designated on a flood hazard map adopted by the community, or otherwise legally designated.
The base flood elevation (BFE) is based on a best guess. Records are broken with regularity and somehow it comes as a surprise every time. 100-year flood? Where did that come from? It’s predictable to wipe the face of the Earth clean every hundred years?
R322.1.4.1 Determination of design flood elevations.
If design flood elevations are not specified, the building official is authorized to require the applicant to comply with either of the following:
Obtain and reasonably use data available from a federal, state or other source.
Determine the design flood elevation in accordance with accepted hydrologic and hydraulic engineering practices used to define special flood hazard areas. Determinations shall be undertaken by a registered design professional who shall document that the technical methods used reflect currently accepted engineering practice. Studies, analyses and computations shall be submitted in sufficient detail to allow thorough review and approval.
The design flood elevation (DFE) is open to reasonable determination by using previous records or a combination of engineering and divination. It is presumptuous for learned professionals to proclaim that which they can’t verify as being truth.
R322.1.4.2 Determination of impacts.
In riverine flood hazard areas where design flood elevations are specified but floodways have not been designated, the applicant shall demonstrate that the effect of the proposed buildings and structures on design flood elevations, including fill, when combined with other existing and anticipated flood hazard area encroachments, will not increase the design flood elevation more than 1 foot (305 mm) at any point within the jurisdiction.
This one is a real hoot. The applicant is required to demonstrate that the proposed construction will not raise the DFE by more than one foot at any point within the jurisdiction. Well now that’s a tall order. I suppose a stadium or shopping mall could be a rock in the toilet tank that went too far… but that’s a complex problem to solve. So let’s assume that the DFE is legally raised a foot by that new school complex… what about all of the existing real estate in the neighborhood that was built to the minimum one foot above the DFE.
One foot? A committee decision. When you see people being airlifted from rooftops do you think, “Well now, they’ll be adjusting that DFE.”
R322.2.1 Elevation requirements.
1. Buildings and structures in flood hazard areas, including flood hazard areas designated as Coastal A Zones, shall have the lowest floors elevated to or above the base flood elevation plus 1 foot (305 mm), or the design flood elevation, whichever is higher.
There is an answer to the problem. Probably a few. Here’s an example: Raise the BFE to “Ya it’ll never get this high.” Then add that magic foot. On top of that is a requirement that everyone in a potential flood zone, no matter what mitigation has been provided, have no-deductible flood insurance.
Buildings and structures erected in areas prone to flooding shall be constructed by methods and practices that minimize flood damage.
The intent of the code is to minimize damage resulting from flooding. While a laudable goal, minimizing damage falls short of the typical intent of most code which is to eliminate damage. An immutable fact is that resisting a flood, as the title of the code section implies, requires enormous hubris.
R322.1.4 Establishing the design flood elevation.
The design flood elevation shall be used to define flood hazard areas. At a minimum, the design flood elevation shall be the higher of the following:
1. The base flood elevation at the depth of peak elevation of flooding, including wave height, that has a 1-percent (100-year flood) or greater chance of being equaled or exceeded in any given year.
2. The elevation of the design flood associated with the area designated on a flood hazard map adopted by the community, or otherwise legally designated.
The base flood elevation (BFE) is based on a best guess. Records are broken with regularity and somehow it comes as a surprise every time. 100-year flood? Where did that come from? It’s predictable to wipe the face of the Earth clean every hundred years?
R322.1.4.1 Determination of design flood elevations.
If design flood elevations are not specified, the building official is authorized to require the applicant to comply with either of the following:
Obtain and reasonably use data available from a federal, state or other source.
Determine the design flood elevation in accordance with accepted hydrologic and hydraulic engineering practices used to define special flood hazard areas. Determinations shall be undertaken by a registered design professional who shall document that the technical methods used reflect currently accepted engineering practice. Studies, analyses and computations shall be submitted in sufficient detail to allow thorough review and approval.
The design flood elevation (DFE) is open to reasonable determination by using previous records or a combination of engineering and divination. It is presumptuous for learned professionals to proclaim that which they can’t verify as being truth.
R322.1.4.2 Determination of impacts.
In riverine flood hazard areas where design flood elevations are specified but floodways have not been designated, the applicant shall demonstrate that the effect of the proposed buildings and structures on design flood elevations, including fill, when combined with other existing and anticipated flood hazard area encroachments, will not increase the design flood elevation more than 1 foot (305 mm) at any point within the jurisdiction.
This one is a real hoot. The applicant is required to demonstrate that the proposed construction will not raise the DFE by more than one foot at any point within the jurisdiction. Well now that’s a tall order. I suppose a stadium or shopping mall could be a rock in the toilet tank that went too far… but that’s a complex problem to solve. So let’s assume that the DFE is legally raised a foot by that new school complex… what about all of the existing real estate in the neighborhood that was built to the minimum one foot above the DFE.
One foot? A committee decision. When you see people being airlifted from rooftops do you think, “Well now, they’ll be adjusting that DFE.”
R322.2.1 Elevation requirements.
1. Buildings and structures in flood hazard areas, including flood hazard areas designated as Coastal A Zones, shall have the lowest floors elevated to or above the base flood elevation plus 1 foot (305 mm), or the design flood elevation, whichever is higher.
There is an answer to the problem. Probably a few. Here’s an example: Raise the BFE to “Ya it’ll never get this high.” Then add that magic foot. On top of that is a requirement that everyone in a potential flood zone, no matter what mitigation has been provided, have no-deductible flood insurance.
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