What Is a Survey Plat?
A survey plat is a scaled legal drawing prepared by a licensed land surveyor (PLS) that graphically depicts the boundaries, dimensions, and features of a parcel of land. Unlike a deed — which describes property in written words — or a simple site plan, the plat is a precise graphic instrument filed in the public record (usually with the county recorder or register of deeds) and referenced in title documents.
Three terms are frequently confused:
- Plat — the graphic drawing showing boundary lines, dimensions, easements, and monuments.
- Survey — the field work and calculations performed by the surveyor; the plat is the deliverable.
- Deed — the legal instrument transferring ownership; it contains a written legal description that the plat illustrates.
The Title Block
The title block appears in the corner (usually lower right) and contains the most critical administrative information:
- Surveyor name, license number, and seal — the PLS's embossed or inked seal is what makes the plat a legal document.
- Firm name and address
- Date of survey and date of certification — important for title insurance because the survey is only accurate as of that date.
- Scale — for example, 1″ = 40′ (one inch equals forty feet). Always verify the scale with the printed scale bar, not just the ratio, because reproduced plats may be scaled differently than the original.
- Project or file number
North Arrow and Scale Bar
The north arrow indicates the orientation of the plat. It may reference true north (astronomic), magnetic north, or grid north (state plane coordinate system). The difference matters: magnetic north varies by location and changes over time (magnetic declination). ALTA/NSPS surveys are required to state which north reference is used.
The scale bar is a graphical ruler printed on the plat. It remains accurate even when a plat is photocopied at a different size — use it to verify dimensions rather than a ruler applied to the stated ratio.
Bearings and Distances
Property lines are described by a bearing (direction) and a distance. Bearings are expressed in the form N 45°30′15″ E, which means: start pointing North, rotate 45 degrees 30 minutes 15 seconds toward the East. Each quadrant (NE, NW, SE, SW) begins from either North or South and ends at either East or West, never exceeding 90°.
Distances are typically given in feet and hundredths of a foot (decimal feet, not feet-inches). For example, 125.47 feet. In some older plats you may see chains or links — one chain equals 66 feet.
You traverse the boundary by starting at a known point of beginning (POB), following each call in sequence, and returning to the POB. If the traverse does not close mathematically, the survey has an error of closure — a quality measure reported as a ratio such as 1:15,000.
Legal Description Systems
Two primary systems describe property boundaries in the United States:
- Metes and Bounds — used in the original 13 colonies and many southern and eastern states. A narrative description that walks the boundary using bearings and distances from a starting point (point of beginning). For example: "Commencing at a concrete monument at the intersection of Elm Street and Main Avenue; thence N 12°15′30″ W, 200.00 feet to a set iron pin; thence S 77°44′30″ W, 100.00 feet…"
- Lot and Block (also called recorded plat or subdivision system) — used in subdivisions where a developer platted land and recorded a map showing individual lots by number. A lot and block description reads: "Lot 14, Block 3, Riverside Subdivision, as recorded in Plat Book 22, Page 44, County Records." This is far simpler but requires the recorded subdivision plat to be on file.
Monuments: Finding the Pins
Monuments are physical markers set at boundary corners. The plat uses abbreviations to describe what was found or set:
| Abbreviation | Meaning | Notes |
|---|---|---|
| FIP | Found Iron Pin | Pre-existing pin discovered during survey |
| SIP | Set Iron Pin | New rebar or rod driven by this surveyor |
| CM | Concrete Monument | Typically a larger 4″×4″ post at major corners |
| PK Nail | Parker-Kalon nail | Set in asphalt or wood for pavement corners |
| MAG | Magnetic nail | Set in concrete or asphalt |
| NPF | No Pin Found | Expected monument was missing |
When a corner shows "NPF," the surveyor calculated the position by mathematical means (traverse or offset) rather than finding a physical marker. This is common in urban areas where pins are paved over or disturbed.
Lot Dimensions and Area
Each boundary line shows its bearing and distance. The lot area is typically stated in the plat either in square feet (for residential lots) or acres (for larger parcels). One acre equals 43,560 square feet. The area shown on the plat is the gross area including any easements — the surveyor calculates it from the boundary traverse, not from a field measurement of the interior.
Easements on the Plat
An easement grants a third party the right to use a portion of property for a specific purpose. Easements appear on plats as hatched or shaded areas with a notation. Common types:
- Utility Easement (UE) — allows utility companies (electric, gas, water, telecom) to install and maintain infrastructure. You typically cannot build permanent structures within a utility easement, but fencing and paving are sometimes allowed with the utility company's consent.
- Drainage Easement (DE) — preserves a flow path for stormwater. Building within a drainage easement may obstruct flow and create flood liability.
- Access Easement — grants right of passage across property, often for a shared driveway or to provide legal access to a landlocked parcel.
- Conservation Easement — restricts development to protect natural resources, often granted to a land trust.
The easement width and beneficiary are stated in the plat note or in a separate recorded instrument. The plat shows the graphic location; the deed of easement contains the legal terms.
Setback Lines vs. Property Lines
Property lines are the legal boundary of ownership. Setback lines (also called building lines) are regulatory lines inside the property beyond which structures must be set back. Setbacks are established by zoning ordinances, deed restrictions, or subdivision covenants — not by the surveyor — but they are often shown on the plat as dashed lines parallel to and inside the property lines. A typical residential front setback might be 25 feet from the front property line.
Important: you own the land within the setback, but you cannot build there. Easements and setbacks may overlap but are legally distinct.
Flood Zone Designations
Many plats include a note referencing the FEMA Flood Insurance Rate Map (FIRM). The note typically reads: "This property lies in Zone X (Minimal Flood Hazard) as shown on FEMA FIRM Panel No. 12345C0123G, effective January 1, 2020." Common flood zones:
- Zone X — minimal flood hazard; outside the 500-year floodplain. No mandatory flood insurance for federally backed mortgages.
- Zone AE — 100-year floodplain with base flood elevations (BFE) established. Mandatory flood insurance required.
- Zone A — 100-year floodplain without detailed BFE study. High risk.
- Zone VE — coastal high-hazard area with wave action; most restrictive construction requirements.
ALTA/NSPS surveys (used in commercial real estate transactions) are required to show flood zone information per Table A Item 16.
Curve Data Table
When a property line follows a curve (common along curved roads), the plat shows a curve data table rather than a simple bearing-distance call. Each curve is labeled C1, C2, etc., and the table provides:
- Delta (Δ) — the central angle of the arc (the angle at the center of the circle)
- Radius (R) — distance from the center of the circle to the curve
- Arc Length (L) — the actual curved distance along the boundary
- Chord (C) — the straight-line distance from the beginning to the end of the arc, with its bearing
- Tangent (T) — sometimes included; the distance from the PC/PT to the PI (point of intersection)
The chord bearing and chord distance are how you would "stake" a curve in the field with conventional methods. GPS can follow the arc directly.
Adjacent Property Owners
The plat typically identifies neighboring parcels by owner name and deed reference. This is important for resolving boundary disputes and for ALTA surveys, which require showing adjoining ownership. The notation might read: "Adjoins: John Smith, Deed Book 45, Page 12."
Legal Description and Recording Information
Near the bottom of the plat, the full legal description (metes and bounds or lot and block reference) is written out. The recording data stamped on the plat after filing shows the instrument number, book, page, and date/time of recording. This is the official reference to find the document in county records.
Types of Surveys
- Boundary Survey — establishes or reestablishes property corners and lines. Most common for residential transactions and construction.
- Topographic Survey — measures existing surface elevations and features (trees, utilities, structures) without re-establishing boundaries. Used by civil engineers for site design.
- ALTA/NSPS Land Title Survey — the most comprehensive survey type, required for commercial real estate transactions. Follows national standards (American Land Title Association / National Society of Professional Surveyors) and addresses 25+ optional Table A items including utilities, easements, flood zones, zoning, and encroachments.
- Construction Layout Survey — sets stakes and offsets in the field to locate proposed improvements.
Common Questions
Can I build on an easement? Generally, no — for structures. The specific restrictions depend on the easement type and the easement instrument. Some drainage easements allow driveways and fencing but prohibit buildings. Always review the recorded easement document before designing improvements.
What does "more or less" mean in a legal description? This phrase (abbreviated M/L) acknowledges that the stated area is approximate. It protects both buyer and seller from minor discrepancies between the described area and what a precise survey would measure. However, the boundary bearings and distances control over the stated area.