Grand Prairie | Flood, Airports and Overlays

Grand Prairie Flood Rules, Airport Zones and Corridor Overlays

Three sets of rules sit on top of Grand Prairie's zoning districts. Floodplain rules in Article 15 of the Unified Development Code (UDC) set how high a home's floor must be and what may be built near creeks and the Trinity River. Airport zones in Appendix N cap building height near two airports. Corridor overlays in Article 7 and Appendix F add design rules along six major roads. The city spans four counties, which matters for the flood maps. The Grand Prairie overview has the summary.

Four Counties, Four Flood Maps

A flood insurance rate map (FIRM) is the Federal Emergency Management Agency (FEMA) map that shows flood zones and flood heights. Sec. 15.6.1 of the UDC adopts four county flood studies and their maps, "and any revisions thereto," and also covers areas "which have not yet been delineated on the FEMA maps, but are known to constitute a special flood hazard." The Census Bureau's Vintage 2025 estimates place parts of Grand Prairie in each of the four counties:

Sources: US Census Bureau, Vintage 2025 Texas city estimates ("Grand Prairie city (pt.)" rows); Grand Prairie UDC Sec. 15.6.1 (October 10, 2023).

Article 15 applies to "all SFHAs within the City of Grand Prairie and its extraterritorial jurisdiction (ETJ)," the area outside the city limits where the City still controls subdivisions. A special flood hazard area (SFHA) is land on the FIRM "subject to inundation by the 1 percent annual chance flood," also called the 100-year flood. The county also decides where a plat is recorded: Sec. 12.12.5 tells the developer to record plats "with the County Clerk at Dallas, Tarrant, Johnson and/or Ellis County."

How High the Floor Must Be

The base flood elevation (BFE) is the height that floodwater has a 1 percent chance of reaching in any year, as shown on the FIRM. Grand Prairie also uses a second, higher-risk measure: the flood level for "fully developed watershed conditions," meaning "the anticipated condition of the watershed after the watershed has undergone ultimate land use development."

Sec. 15.18.1.A sets the rule for homes. New construction and substantial improvements of any residential structure "shall have the lowest floor elevation (including basement) be the greater of one foot above the base flood elevation (BFE) for fully developed conditions in the watershed or two feet above the FEMA FIRM 100-year (1% annual chance) BFE that utilizes existing land use conditions." A substantial improvement is work costing 50 percent or more of the building's market value. Parking lots must be at least 1 foot above the BFE, air conditioning pads sit at the same height as the lowest floor, and all roads must be at least 2 feet above the BFE "unless approved otherwise."

• Homes must be anchored against flotation, collapse and sideways movement, built with flood-resistant materials, and have equipment placed to keep water out.
• No critical facility may be placed within the 500-year floodplain.
• Fences may stand in the floodplain if the part below the lowest floor elevation lets stormwater pass through; a fence needs its own building permit.
• After construction, an elevation certificate from a licensed Texas surveyor or engineer is required for every building within 200 feet of the 100-year floodplain before occupancy.

Permits, Floodways and Lots in the Floodplain

Sec. 15.15.1 requires a City Floodplain Development Permit "for all proposed development in a Special Flood Hazard Area or floodplain," issued by the Stormwater Department. On a lot of less than one acre, Sec. 15.15.2.C says "the floodplain permit can be included with the building permit." Article 22 lists a floodplain permit fee of $300 for 3 to 20 acres and $500 above 20 acres, and a permit expires one year after release. Drainage or floodplain reviews of private projects are paid into an escrow account, based on a consultant's estimate.

The floodway, the stream channel and nearby land that must stay open to carry floodwater, is the strictest area. Sec. 15.7.1 prohibits "fill, new construction, substantial improvements of non-conforming structures and other development" there unless a registered engineer shows it will not raise flood flows, damages or the BFE for fully developed conditions. Any floodway encroachment needs a FEMA Conditional Letter of Map Revision (CLOMR) before the City issues a permit. Encroachments may raise flood levels by no more than one foot, and "zero increase for the ultimate flow conditions," and there may be "no loss of valley storage within the fully developed 100-year (1% annual chance) floodplain."

The lot rules follow from this. Table 6A note 1 says residential lots reaching into a designated floodplain need one acre, or the floodplain part must be dedicated "as a Storm Water Management Area to the City of Grand Prairie." Plats must show lowest floor elevations for lots within 200 feet of a 100-year floodplain, and Sec. 16.2.1.E requires a site plan for any use other than single-family or two-family on land within 200 feet of a studied floodplain. Under Article 14, erosion hazard setbacks apply along natural streams, and "a person commits an offense if the person erects or maintains a structure within an erosion hazard setback." Detention basins are required "when downstream facilities are not adequately sized."

Sellers carry a duty too. Sec. 15.12.1 requires anyone who sells a house or lot in a designated flood hazard area to tell the buyer in writing, and the lender must tell the borrower that flood insurance is available, "no later than two (2) working days prior to closing."

Airport Height Zones

Sec. 7.2.1 says the airport hazard district exists "to prevent the establishment of hazards or obstructions to air navigation," and that the overlay districts for "Dallas/Fort Worth International Airport and Grand Prairie Municipal Airport are found in Appendix N." Appendix N was last updated November 5, 2024 by Ordinance No. 11647-2024. Each airport is surrounded by imaginary surfaces, sloped or flat planes in the air that no building or tree may pierce. For the DFW Airport, the zones come from hazard maps dated December 1970 and incorporated by reference. For Grand Prairie Municipal Airport, Section 2B sets four zones around Runway 18/36:

• Approach zones start 500 feet wide, 200 feet beyond each runway end. Heights rise 1 foot for each 20 feet out to 5,000 feet for Runway 18, and 1 foot for each 34 feet out to 10,000 feet for Runway 36.
• Transition zones rise 1 foot for each 7 feet outward from the sides of the runway and approaches.
• The horizontal zone is a flat plane 150 feet above the airport elevation, "or a height of 738.4 feet above mean sea level," inside arcs of 10,000 feet drawn from each end of the runway's primary surface.
• The conical zone rises 1 foot for each 20 feet for another 4,000 feet, up to 350 feet above the airport elevation.

Most houses fall below these planes. Section 7.2B.2.E says nothing prohibits "any tree or structure to a height up to fifty (50) feet above the surface of the land." In the horizontal and conical zones, and in approach zones more than 4,200 feet from a runway end, no permit is required for a structure under 75 feet unless the ground level carries it above the limit. Land uses may not create glare, confusing lights, radio interference or bird strike hazards. A decision of the Chief Building Official may be appealed to the Zoning Board of Adjustment within 21 days. Preliminary plats must show "Avigation Zones," and final plats carry an "Avigation Release." Rooftop features allowed 15 feet above a district height limit under Sec. 6.10.3 must also stay clear of these surfaces.

The 2025 state housing laws treat airports separately. SB 15 small lots and SB 840 apartments do not apply to land within 3,000 feet of an airport or military base, under Local Government Code 211.052(b) and Section 218.101(c). The UDC does not map that 3,000-foot line, so check it before relying on either law near Grand Prairie Municipal Airport.

Corridor Overlays and Downtown

An overlay district adds rules on top of the base zoning without changing the uses. Article 7 creates six corridor overlays, and Appendix F, last updated November 16, 2021 by Ordinance No. 11125-2021, holds their standards.

Source: Grand Prairie UDC Article 7, Sections 4, 5 and 8 to 11 (September 2, 2025). The boundaries are drawn in Appendix F.

Appendix F applies its building standards to new commercial, office, retail, restaurant, lodging, institutional and automotive buildings, and says Appendix W "shall apply to the construction of new single-family detached, single-family attached, single-family townhouse, and multi-family development." Non-residential development in a corridor overlay needs site plan approval from the Planning and Zoning Commission and the City Council at a public hearing, and Sec. 16.2.1.F requires a site plan for any use other than single-family or two-family there. Appendix W, Section 4.I.A, says SB 840 apartments inside a corridor overlay "shall meet all exterior design recommendations." Mixed-use projects earn a bonus: for each 10 percent of first-floor area used for commercial or retail, the developer may raise the maximum units per acre by 10 percent and the maximum height by 10 feet.

Article 7 also creates Central Business overlay districts along the Main Street and Jefferson Street corridor, with their standards in Appendix R, a Hospital District with its rules in Appendix O, and the Light Industrial-Limited Standards suffix district in Appendix Q. Planned developments, the custom districts covered on the zoning districts page, can replace many base rules, so read the PD ordinance for any site that has one.

Where to Go Next

Related on VanPlex: the Grand Prairie overview, insurance and flood and SB 840 commercial to residential.

Frequently Asked Questions

Official sources (checked October 2026)