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FEMA Questions


Q: What is FEMA?

The Federal Emergency Management Agency (FEMA), a former independent agency, became a part of the new Department of Homeland Security in March, 2003. FEMA is responsible for assisting communities in responding to, planning for and recovering from natural and other disasters in the US. One of the many functions of this agency is to oversee the Technical Services Division, which conducts hydrologic and hydraulic analyses to identify flood hazards in communities throughout the United States . Private engineering firms and Federal and State agencies, under FEMA guidelines, perform many of those analyses.  
Using the information gathered by the Technical Services Division, FEMA publishes National Flood Insurance Program Maps or FIRMs (Federal Rate Insurance Maps) that indicate a community’s flood hazard areas and the degree of risk in those areas. These maps are used by engineers, surveyors, and insurance providers to complete FEMA Elevation Certificates.

Q: How does a surveyor determine the elevations needed for a FEMA Certificate?

The surveyor locates the nearest FEMA Benchmark to the property being surveyed. Each benchmark has a known elevation, with all benchmarks being relative to one another. (Theoretically, a surveyor can use any known benchmark and obtain the same elevations on the subject tract.) The surveyor determines the subject tract elevations based on the known elevation of the benchmark using specially designed and calibrated equipment.

Q: What are the three types of FEMA certificates?

In Section “C1” of the FEMA Certificate, there are three checkboxes for each of the three types of Elevation Certificates. They are “Construction Drawings”, “Building Under Construction” and “Finished Construction”. The checkbox for the first two choices states that a new elevation certificate is required when construction of the structure is complete.

Q: What are the three types of FEMA Elevation Certificates needed by a builder?

1. The first type is for “Construction Drawings” . This certificate shows actual elevations determined by the surveyor’s fieldwork, as well as proposed elevations provided by the builder. The surveyor provides the actual elevations at “lowest adjacent grade” (LAG) and “highest adjacent grade” (HAG) in the general area of the building line of the subject tract. The builder provides the proposed “top of bottom floor” (finished floor elevation), the “attached garage”, the “lowest elevation of machinery and/or equipment servicing the building” and both the number and total area of permanent openings (flood vents) on the structure. All elevations are in reference to a known benchmark, which is noted on the certificate. The Base Flood Elevation (BFE) is also noted; and can be found on the FIRM panels. The builder also provides information about the type of foundation planned, referencing FEMAs building diagrams numbered 1-8. The “Construction Drawings” elevation certificate is generally required by the City of Houston, Bellaire, and City of West Univerisity Place for permitting for all proposed structures in the 100-year flood plain.

2. The second elevation certificate needed is for “Building Under Construction”. The elevations needed are the same as for the “Construction Drawings” certificate, but at this stage, the elevations are now actual numbers instead of proposed numbers. These elevations are generally obtained when the surveyor performs the form survey. The “Building Under Construction” elevation certificate is generally required by the City of Houston, Bellaire, and City of West Univerisity Place before a concrete slab can be poured.

3. The third and final elevation certificate needed is for “Finished Construction”. In order for the certificate to be submitted for flood insurance, the structure needs to be near completion with all flood vents installed and the concrete pad for the HVAC system in place. This certificate is required in order to obtain flood insurance. Either/or the lender and Title Company usually require it as well.

Q: What are the City of Houston requirements in regards to finished floor elevations for new construction for property in the 100-year flood plain?

The City requires that the finished floor elevation, attached garage elevation, and elevation of machinery servicing equipment be no less than 1 foot (12") above the Base Flood Elevation as determined from the FIRMs.

Q : The FIRM shows my lot is in the mapped floodplain, but when I had my elevation certificate done, my house is above the Base Flood Elevation (BFE). Doesn’t this mean I’m out of the floodplain?

Building above the BFE will certainly help keep the cost of flood insurance down, as well as being a selling point at resale, but you cannot build “outside of the floodplain.” The various floodplain zones are determined by hydrologic and hydraulic analyses by private engineering firms and Federal and State agencies, under FEMA guidelines. To be considered outside of the floodplain would require a Letter of Map Change of which there are six (6) different types, or a change in the flood zone determination when FIRMs are updated and reissued. To summarize: you can build above the base flood elevation, but this does not mean that you are out of the flood plain.

Q : What year were the last FEMA maps issued for the Houston area?

As a general rule, surveyors in the Greater Houston area reference floodplain elevations based on FIRMs dated April 20, 2000. These maps are based on 1929 North American Vertical Datum (1929 NAVD) with a 1973 adjustment.

Q : Many areas of the city flooded after Tropical Storm Allison in 2001 that were not considered to be in a “flood zone”. Is FEMA planning to update and revise the maps for the area?

FEMA is in the process of updating some of the FIRM panels for the Houston area. The new maps have not been published as of yet, so we continue to use the April 20, 2000 maps.

Q: Why is there a different adjustment applied to FIRM benchmarks in the Brays Bayou Watershed?

Lichliter/Jameson & Associates, (LJA) performed a hydraulic study in this area in 1994 at the request of the Harris County Flood Control District. The FIRM panels for the area were based on this study, typically referred to as the 1987 adjustment. The confusion occurs when surveyors reference the benchmarks on these panels, which are on the 1973 adjustment. Therefore, surveyors use a conversion table that shows the adjustment from the 1973 benchmark elevations to the 1987 elevations established by LJA. Essentially what has happened is that the land in this area has subsided, which is reflected on the FIRM panels, but not in the benchmarks printed on those panels.

Q: I want to build an addition to my house, which is located in the 100-year flood plain. I was told that there are some limitations associated with improvements for homes in the flood plain. What are they?

The City of Houston will not grant a building permit for improvements if the cost of those improvements exceeds 50% of the appraised value of the current structure.

Q: I was planning to build a new home with a “slab on grade foundation” The City has just rejected my permit for this type of foundation and informed me that I must build a raised slab with flood vents. How did they determine this? 

In areas that in Zone A or Zone AE, if the “lowest adjacent grade” (LAG) is more than 24” below the Base Flood Elevation (BFE), the City of Houston will require the foundation to conform to FEMAs Diagram 8 (pier and beam with flood vents) or Diagram 5 (elevated on piers, posts or columns). This is sometimes the case in the Brays Bayou Watershed, and occasionally in the Houston Heights.



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