Harris County, TX Environmental Rules: Flood Elevation Requirements (2026)
Key Facts
- Minimum freeboard
- 24 in. above 500-year flood elevation
- Floodway structures
- 36 in. above 500-year elevation
- Certification
- Registered surveyor or engineer required
- Applies in
- Unincorporated Harris County floodplain
Summary
New construction in Harris County's floodplain must be elevated well above base flood, not just to it, under the county's post-2023 freeboard rule.
The top of the subfloor of the lowest habitable floor must be elevated to 24 or more inches above the 0.2 percent or 500-year flood elevation or 12 inches above the level of the crown of the nearest public street, whichever is higher, except in a floodway where the bottom of the lowest supporting member of the structure shall be elevated 36 or more inches above 0.2 percent or 500-year flood elevation.
Full Breakdown
For a Class II permit, Harris County requires the lowest habitable floor's subfloor at 24+ inches above the 0.2%-annual-chance (500-year) flood elevation, or 12 inches above the adjacent street crown, whichever is higher. In a floodway, the lowest supporting member must clear 36+ inches above that 500-year level. Structures on fill or piers face separate elevation and certification rules, and a licensed engineer or surveyor must file elevation certificates before framing and again at completion.
Violations & Fines
No occupancy or final approval without a certified elevation certificate; the County Engineer can deny or condition permits, and non-conforming construction can void flood-damage rebuild protections after a storm.
Frequently Asked Questions
Does Harris County use the 100-year or 500-year flood level?
Who verifies the required elevation was met?
Sources & Official References
Other rules in Harris County
Texas rules heatmap·Compare Harris County to another location·View the Texas environmental rules overview
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