JackMentink
Silver Member
The bottom line is that you can build in a floodplain as long as the building floor is above the base flood elevation (BFE). Ask to look at the Fema flood map and see if you are in a approximate zone A or in an area that has an actual study done and has a defined flood study and elevations (usually zone AE). Based on these two options:
1) Approximate zone A - these are done off of USGS topo mapas which have 10' contour lines and are at very large scale. I have seen flood maps off by as much as 400 feet horizontally in there location of the flood plain. If you are in an approximate zone A, then you will need a Registered Engineer (where not all bad) to possibly do a LOMR (Letter of Map revision). This could get expensive because you have do a study.
2) Flood Study completed and in Zone AE - This is actually the better alternative as you have defined flood elevations. While not always real precise, they are easy to check. You can hire either a surveyor or a Registered Engineer to certify your building elevation in relation to the flood plain elevation. Even if your building is below BFE you can always bring in some fill and raise it above BFE and still build it. The only restriction is that you can not build in the "floodway" (another term) which is defined as a location that is usually marked on the flood maps and is very close to the actually creek channel. If you would choose to to raise it up above BFE then the only requirement the zoning guy could enforce on you would be requiring a (yet another term) "no-rise certificate" . This is a document
filled out by an engineer that states that the fill you have place in the flood plain will not cause the Base flood elevation to rise more than .10 feet. None of these are ususally a big deal.
I would work with an engineer who understands flood plains , instead of a Surveytor who can only do the elevation certificate.
You can do the flood proofing thing for the new building but, I wouldn't recommend it it increases cost and lowers the functionality of the building.
A final word, most flood plain administrator don't understand the depth of FEMA regulations in regards to flood plains and you will hear all sorts of misquotes and " no you can't do that" , becuase its easier to say no than it is to dig into the depths of the Flood plain requirements and see what you can do.
Hope this helps some.
Jack Mentink P E
Principal
Integrity Engineering, Inc.
Rolla, MO
1) Approximate zone A - these are done off of USGS topo mapas which have 10' contour lines and are at very large scale. I have seen flood maps off by as much as 400 feet horizontally in there location of the flood plain. If you are in an approximate zone A, then you will need a Registered Engineer (where not all bad) to possibly do a LOMR (Letter of Map revision). This could get expensive because you have do a study.
2) Flood Study completed and in Zone AE - This is actually the better alternative as you have defined flood elevations. While not always real precise, they are easy to check. You can hire either a surveyor or a Registered Engineer to certify your building elevation in relation to the flood plain elevation. Even if your building is below BFE you can always bring in some fill and raise it above BFE and still build it. The only restriction is that you can not build in the "floodway" (another term) which is defined as a location that is usually marked on the flood maps and is very close to the actually creek channel. If you would choose to to raise it up above BFE then the only requirement the zoning guy could enforce on you would be requiring a (yet another term) "no-rise certificate" . This is a document
filled out by an engineer that states that the fill you have place in the flood plain will not cause the Base flood elevation to rise more than .10 feet. None of these are ususally a big deal.
I would work with an engineer who understands flood plains , instead of a Surveytor who can only do the elevation certificate.
You can do the flood proofing thing for the new building but, I wouldn't recommend it it increases cost and lowers the functionality of the building.
A final word, most flood plain administrator don't understand the depth of FEMA regulations in regards to flood plains and you will hear all sorts of misquotes and " no you can't do that" , becuase its easier to say no than it is to dig into the depths of the Flood plain requirements and see what you can do.
Hope this helps some.
Jack Mentink P E
Principal
Integrity Engineering, Inc.
Rolla, MO