Floodplain Development Regulations After Hurricane Harvey
In the wake of the historic flooding caused by Hurricane Harvey, both the City of Houston
and Harris County undertook major efforts to revise their floodplain development
regulations. The primary objective of these updates was to reduce future flood losses by
imposing more stringent requirements on new development and substantial improvements
within flood-prone areas.
Harris County Floodplain Regulation Updates
Harris County adopted its updated floodplain regulations unanimously on December 5,
2017, with an effective date of January 1, 2018. These changes significantly raised the
elevation standards for development within the 100-year floodplain.
Under the new regulations, the lowest habitable floor of any new structure located within
the 100-year floodplain must be elevated 24 inches above the 500-year flood elevation.
This represents a substantial increase from the previous requirement, which only required
buildings to be elevated 18 inches above the 100-year flood elevation.
In addition to higher elevation requirements, Harris County eliminated slab-on-grade
construction within the 100-year floodplain. All new buildings in these areas must now
utilize pier-and-beam foundations, maintaining open space below the structure to allow floodwaters to pass beneath the building. Projects proposing slab-on-grade construction within the 100-year floodplain are required to obtain a FEMA Letter of Map Revision
(LOMR) before submitting for a permit.
City of Houston Chapter 19 Revisions
Following similar objectives, the City of Houston initiated revisions to its floodplain
ordinance—commonly referred to as Chapter 19 of the Code of Ordinances. On April 4,
2018, City Council voted to adopt amendments that significantly strengthen floodplain
development standards. These amendments became effective September 1, 2018.
One of the most impactful changes under the revised Chapter 19 is the increase in flood protection elevation requirements. New structures and substantial improvements are located within the Special Flood Hazard Area must now be elevated 24 inches above the 500-year flood elevation, replacing the former standard of 12 inches above the 100-year flood elevation.
The updated ordinance also expanded mitigation requirements for fill placed within the 500-year floodplain. Previously, compensatory storage was only required for fill placed in
the 100-year floodplain. This expansion adds another layer of complexity to site planning
and floodplain permitting.
Impacts on Development and Permitting
These regulatory changes present new challenges for floodplain development, affecting
site design, construction methods, and overall permitting timelines. Higher finished floor
elevations, foundation constraints, and expanded mitigation requirements require early
coordination and careful planning to avoid delays.
As development standards continue to evolve in the post-Harvey era, staying informed is
critical. Our team remains committed to helping clients navigate these regulations
efficiently while delivering compliant, resilient designs that meet both regulatory and
project goals.
Chapter 19 Floodplain Ordinance – Summary of Changes
| Category | Previous Requirements | Revised Requirements (Effective 9/1/2018) |
|---|---|---|
| Regulated Area | 100-year floodplain | 100-year and 500-year floodplains |
| Flood Protection Elevation | 100-year + 12″ | 500-year + 24″ |
| Flood Protection (Critical Facilities) | 500-year + 12″ (critical facilities) | 500-year + 36″ (critical facilities) |
| Zero Net Fill | Required in 100-year floodplain | Required in 100-year and 500-year floodplains |
| Foundation Type | 100-year & 500-year floodplains; any floodway; Pier & Beam | 100-year & 500-year floodplains; any floodway; Pier & Beam |
