If your home or business has been placed in a flood hazard area, whether it is a floodplain or floodway, your property will be subject to certain restrictions imposed by Chapter 19 of the city code. As we reported in our July issue these restrictions could place a financial burden on the property owner when substantial improvements or repairs are necessary.

Our previous article focused on the "no build" aspect of the ordinance, which does not allow any new construction or substantial improvements to structures in a floodway. Substantial improvements according to Chapter 19 are any "reconstruction, rehabilitation, addition, or other improvement of a structure, the cost of which equals or exceeds 50% of the market value of the structure." The 50% is cumulative over a period of 10 years for flood damage repairs. So no permits will be issued for property owners in a floodway to make repairs, improvements, and additions if the cost will be over 50% of the value.

Recently redrawn floodplain maps put many more area homes in the floodway and floodplain. Both the floodplain and floodway designations are defined by federal law. They are determined by calculations based on computer models, surveys and other data. A floodway is a primary runoff area along a waterway, and thus very likely to get high water during a very heavy rain event. All floodways are located in floodplains, which are larger areas adjacent to waterways. Areas in the floodplain, but not in the floodway, will flood much less frequently. There are several floodplain designations including 10-year,100-year and 500-year. Being in the 100-year floodplain, for example, means that you would have a 1% chance of flooding each year. Which floodplain you are in will determine your flood insurance rate, which is set by FEMA.

Chapter 19 restricts floodplain property in much the same way that it does floodway property. There is an exception, however. In the floodplain new construction and substantial improvements and repairs (50% or more of the value) will be allowed if the structure meets the floodplain requirements. The ordinance says "any residential structures within the special flood hazard areas shall have the lowest floor and all utilities elevated to at least the minimum flood protection elevation." A structure in the floodplain that is built or substantially improved will have to at least be at the base flood elevation or 1 foot above depending on the floodplain zone.

Existing homes that do not meet the flood elevation requirements will have to be elevated in order to have substantial improvements or repairs made. It may be possible to elevate homes on piers and beams; elevating homes on slabs may be difficult or impossible. So if a home on a slab is in the floodplain and is not above the flood elevation, the home will likely have to be rebuilt if it needs substantial improvements or repairs. Any improvements, repairs, or remodeling that does not cost at least 50% or more of the value of the structure will be allowed without the elevation requirement.

The accompanying map shows an area of the White Oak Bayou floodplain along West T.C. Jester north of I-10. The floodplain is indicated by the shaded areas with slanted lines for the floodway. The City has designated zones to indicate specific building requirements in the floodplain. The A Zones mean the land within the floodplain is subject to a one percent or greater chance of flooding (100-year floodplain). The X zone area is in an area that is subject to a 0.2 percent or greater chance of flooding in any given year (500-year floodplain).

In Houston flooding is not always restricted to those areas in the floodway or floodplain. Due to flat terrain and clay soils severe storms and intense rain events can cause flooding in parts of the city that are not in designated flood hazard areas. Mapping along the watersheds, however, is the way FEMA assesses flooding risk for establishing flood insurance rates. The problem is that a lot of development in the floodplain took place before floodplain regulations were adopted. Now many homeowners in 30 and 40 year old homes find themselves in the path of the flood hazard zone. The city that once allowed the construction of their homes along bayous and streams is now imposing restrictions on those homes.

The city ordinance allows the property owner to apply for a variance if meeting the floodplain requirements creates an "exceptional" hardship. A Public Works appeals board will determine if the variance can be granted. The applicant will have to prove that the hardship is exceptional and that the structure will be designed to minimize flood damage.

A property owner in the floodplain can also submit a Letter of Map Amendment (LOMA) to FEMA to remove their property from the floodplain. The property owner will also have to submit mapping and survey information to FEMA. This will most likely involve hiring a licensed land surveyor or registered professional engineer to prepare an elevation certificate for the property. FEMA will review the documents and issue a decision in 4 to 6 weeks. This appeal process is only available to property owners who are at or above the base flood elevation(BSE).

As more high density development takes place in the city, flooding may occur in areas that have not been prone to flood in the past. It is not inconceivable that the floodplain area could be increased again in the future, placing more homes and businesses in the flood hazard restrictions.