Blog · September 27, 2026
Floodplain Line vs Lot Line
A floodplain line is a mapped water elevation. A lot line is the edge of the property.
Platbookmapper is an Amazon Associate. If you buy through an Amazon link on this page, we earn a commission. The link is a product, not the county map.
Plats sometimes show a flood line or a finished-floor note inside the lot. The lot still includes the low ground. You may not be able to build the living space there.
On the recorded sheet
FEMA maps and the plat can disagree because they were drawn for different jobs. The plat is the lots. The flood map is the insurance hazard.
The mix-up to avoid
Filling in a floodplain is a permit question. It is not accomplished by redrawing the parcel on a screenshot.
Find the county map
Start at Platbookmapper, search the county, and open the local GIS link. Write down the parcel number before you compare the screen to a paper plat.
Not a survey. County GIS and tax parcel maps are assessment and planning layers. They are not a substitute for a recorded plat, deed, or licensed survey.