Why could a building’s flood zone change?
You heard Harris County is redrawing its flood maps and wonder what that means for a building you like. The current maps decide a building’s zone today. Draft maps could change some zones later. That’s why we date every flood check on our list of buildings by zone.
As of Oct 25, 2026, 128 tracked new builds were Zone X, 9 shaded X and 3 Zone AE on the current effective maps.
What is MAAPnext?
MAAPnext is Harris County’s project to update its flood maps, led with the Harris County Flood Control District. It uses newer rainfall data, updated terrain and the drainage projects built since the last maps.
Draft maps go through public review before FEMA makes them effective. Until then, the current Flood Insurance Rate Map (FIRM) is the official map for insurance and building rules.
Current FIRM vs. draft: what’s the difference?
| Current effective FIRM | MAAPnext draft | |
|---|---|---|
| Official for insurance and permits | Yes | Not yet |
| Data age | Older studies | Newer rainfall and terrain data |
| Can change a building’s zone | It’s the zone today | Possibly, once effective |
| What we show on cards | The zone, with the date | A note where it differs |
A draft might move a building into a different zone, or out of one. Neither change is a verdict on the building.
Facts, never verdicts
We show the current zone, note where a draft differs, and date both. We never call a building safe or unsafe based on a map.
What is Chapter 19, and when does it apply?
Chapter 19 is the City of Houston’s floodplain ordinance. It sets building rules, like how high new structures must sit, for construction inside city limits. It doesn’t apply in unincorporated Harris County or in other cities.
None of the three tracked Zone AE buildings is inside the City of Houston (Oct 25, 2026). Areas like the Heights are inside the city, so Chapter 19 applies to new construction there. Katy and much of Cypress sit outside it.
How do LOMR-F letters fit in?
A LOMR-F revises the current effective map for a structure or parcel built on fill. Two of the three Zone AE buildings have LOMR-F letters pending. Our guide on LOMR-F letters covers what they show.
What should a renter do with this?
- Check the building’s current zone and the date it was checked.
- Ask whether a draft map shows something different.
- Read the §92.0135 notice for the floodplain and five-year flooding answers.
- Ask what the generator covers.
Our guide on FEMA zones explains how to look up an address yourself.
How draft maps become effective
Flood map updates follow a public process. Draft maps are released, the public can review and comment, appeals are heard, and FEMA issues a final determination. Only then do the new maps take effect for insurance and building rules. The whole process can take a long time, so the current FIRM stays in force until then.
For renters, that means two things. First, the zone on your card today is the official one. Second, a building’s zone could change during or after your lease, which is why we date every check.
Where to look yourself
Harris County Flood Control District publishes MAAPnext information and map viewers. You can compare the current effective zone with draft data for an address. We do the same for every building on your shortlist and note where they differ.
How do we help?
We check every building on your shortlist against the current FIRM, note any draft differences, and ask for the flood notice. You get the facts with dates, the same day during hours. It’s free to you, and your rent is the same either way.