How to Read a Plat Map

What a plat map is

A plat map is the drawing component of a recorded plat — the legal document that subdivides land into lots. The terms are used interchangeably in practice: "plat map" emphasizes the scaled diagram, "plat" the full recorded instrument including certifications and notes. Once recorded, the geometry on the map is legally binding: lot lines, easements, and street dedications all trace back to it.

The anatomy of a plat map

Plat maps look intimidating because everything is annotated. In practice they have a consistent anatomy, and reading one is a fixed sequence:

1. 01
   Start at the title block

   Usually the lower-right corner. It names the subdivision, the survey or abstract it sits in, the city and county, the owner, the surveyor of record, the drawing scale, and the date. The recording stamp (volume/page or instrument number) confirms it's the recorded version.

2. 02
   Orient with the north arrow and scale

   Nearly all plats are drawn with a north arrow and a stated scale (1" = 100' is common). Confirm orientation before reasoning about street frontage or adjacency.

3. 03
   Locate the lot by block and lot number

   Lots are numbered within blocks; blocks are numbered or lettered within the subdivision. A legal description like "Lot 12, Block 3" is a direct address into the map.

4. 04
   Trace the boundary with bearings and distances

   Every lot line carries a bearing (compass direction) and distance (feet). Curved lines along cul-de-sacs carry curve data instead — radius, arc length, and chord. Following them around the lot reproduces its exact legal boundary.

5. 05
   Identify the dashed lines

   Dashed and dotted lines are almost always easements — utility, drainage, or access. Each is labeled with its width and purpose (e.g., "10' U.E." for a ten-foot utility easement). These constrain where structures can go.

6. 06
   Read the plat notes

   The fine print along the margins. Building lines, drainage requirements, deed restrictions, and dedication language live here — and they bind every lot on the plat.

Common plat map symbols and abbreviations

B.L. (Building line)

The setback line — the minimum distance from the street within which no structure may be built.

U.E. (Utility easement)

A strip reserved for utility infrastructure. Usually dashed, labeled with its width.

D.E. (Drainage easement)

A strip reserved for stormwater flow or drainage infrastructure. Building over it is typically prohibited.

A.E. (Access easement)

A strip granting passage across one lot to reach another.

R.O.W. (Right-of-way)

Land dedicated for public streets, alleys, or corridors, labeled with its width.

Reserve (or Restricted Reserve)

A tract set aside for a stated non-residential purpose — detention, landscaping, commercial use, or common area.

Bearings (e.g., N 45°30'15" E)

The compass direction of a boundary line, measured in degrees, minutes, and seconds from north or south.

Curve table (R, L, C)

Radius, arc length, and chord data for curved boundary lines, usually collected in a table keyed to curve numbers on the map.

F.I.R. / F.I.P.

"Found iron rod" / "found iron pipe" — physical survey monuments located at boundary corners.

Plat map vs. survey vs. site plan

Reading a plat map like a contractor

A title company reads a plat map for boundary certainty. A contractor reads it for project intelligence. The high-signal fields, in order:

1. 01 ·Lot count and lot sizes. Forty 50-foot lots is a production homebuilder play; four 2-acre reserves is commercial development. The trade mix follows.
2. 02 ·The owner entity in the title block. Usually an LLC — cross-reference it to find the developer behind the project.
3. 03 ·The surveyor / engineering firm of record. Civil firms repeat with the same builders; the firm on the plat predicts who builds it.
4. 04 ·Reserves and their stated use. "Restricted Reserve A — detention" is site work; "Restricted Reserve B — commercial" is a future vertical project.
5. 05 ·New right-of-way dedications. New streets mean paving, utilities, and site contracts before any building permit appears.

Common questions

For what a plat is and the types you'll encounter, start with what is a plat. For how the document gets created and approved, see the platting process guide.