§ 19-33. Base flood elevation requirements in Houston special flood hazard areas.

(a)

The following additional requirements shall apply in Zones A1—30, AE, AH, A, and A99:

(1)

For any addition to, and new construction and substantial improvement of, any residential structure:

a.

The lowest floor and all utilities must be elevated to at least the minimum flood protection elevation, except that additions which are no greater than 33% of the habitable area of the structure shall be permitted to be constructed at one foot above base flood elevation; and

b.

If the flood elevation of a garage attached to an addition is lower than the minimum flood protection elevation, the garage must meet the requirements of item (8) of section 19-32 of this Code.

(2)

Any addition to, and new construction and substantial improvement of, any nonresidential structure:

a.

Shall be elevated to at least the minimum flood protection elevation measured to the lowest floor; or

b.

Shall, along with sanitary sewerage facilities, be floodproofed to the minimum flood protection elevation.

(b)

The following additional requirements apply in an X Shaded Zone:

(1)

Any addition to, and new construction of any residential structure shall:

a.

Have the lowest floor and all utilities elevated to at least the minimum flood protection elevation, except that additions which are no greater than 33% of the habitable area of the structure shall be permitted to be constructed at the same elevation as the structure it is being added to; and

b.

If the flood elevation of a garage attached to an addition is lower than the minimum flood protection elevation, the garage must meet the requirements of item (8) of section 19-32 of this Code.

(2)

Any addition to, and new construction of nonresidential structure:

a.

Shall be elevated to at least the minimum flood protection elevation measured to the lowest floor; or

b.

Shall, along with sanitary sewerage facilities, be floodproofed to the minimum flood protection elevation.

(c)

The following additional requirements shall apply in an AO Zone:

(1)

All additions to, and new construction and substantial improvement of, any residential structure within an AO Zone shall have the lowest floor and all utilities elevated above the highest adjacent grade to at least two feet above the depth number in feet specified on the FIRM for the site or at least three feet above the highest adjacent grade if no depth number is specified. If the floor elevation of a garage attached to an addition is lower than the minimum flood protection elevation, the garage must meet the requirements of item (8) of section 19-32 of this Code.

(2)

All additions to, and new construction and substantial improvement of, any nonresidential structure within an AO Zone shall have the lowest floor elevated above the highest adjacent grade at least two feet above the depth number specified in feet on the FIRM or at least three feet above the highest adjacent grade where no depth number is specified or, together with utility and sanitary sewerage facilities, be completely floodproofed to or above that level.

(d)

All structures to be constructed in whole or in part within these zones shall be designed with adequate drainage paths around structures on slopes to guide floodwaters around and away from those structures.

(e)

For critical facilities located in an area that is subject to a 0.2 percent or greater chance of flooding in any given year (X Shaded Zone), all additions, new construction, and substantial improvements shall have the lowest floor elevated or floodproofed to at least three feet above the elevation that is subject to a 0.2 percent or greater chance of flooding.

(Ord. No. 2018-258 , § 2(Exh. A), 4-4-2018)