Plat vs. Survey: Why the Difference Matters for Missouri Homebuyers

Understanding These Two Key Tools in St. Louis Real Estate

When you’re buying property in Missouri—especially in the St. Louis area—you’ll likely hear the terms plat and survey. They sound similar, which is why many homebuyers and even some agents use them interchangeably. But these two documents serve very different purposes, and knowing the distinction can save you time, stress, and unexpected expense during your real estate transaction.

What Is a Plat Map?

A plat map is a recorded map that outlines the boundaries and layout of a subdivision or town. It’s used to show how larger parcels of land have been divided into individual lots.

A plat typically includes:

• Lot and block numbers

• Streets and right-of-way areas

• Public easements

• Monuments or reference points

• The overall layout of a subdivision

Before land can be legally subdivided or sold as individual lots in Missouri, developers must submit a plat for review and approval by local government authorities such as county assessors and municipal planning departments.

Boundary Adjustment Plats

Beyond subdivision plats, Missouri property owners sometimes file boundary adjustment plats. These are required when:

• Two neighboring owners want to shift or redefine their shared boundary

• The property line needs updating to reflect an agreed-upon change

A licensed surveyor measures both parcels, and after the plat is signed by both property owners and approved by the local governing body, the new boundaries become official. Tax assessments are then based on the newly adjusted property lines.

What Is a Boundary Survey?

Unlike a plat, which shows many properties at once, a boundary survey focuses on one specific property and provides highly detailed, precise measurements.

A boundary survey typically identifies:

• Exact property lines and dimensions

• Locations of structures (home, garage, shed, etc.)

• Encroachments (such as a neighbor’s fence crossing the line)

• Easements or shared access areas

• Compliance with municipal setback requirements

This level of detail is extremely valuable for buyers who plan to:

• Add a home addition

• Build a garage or pool

• Install a fence

• Confirm the accuracy of an existing boundary

In most Missouri real estate transactions, a boundary survey is required when the buyer wants survey coverage on their title insurance policy. A plat alone does not offer enough detail for that coverage.

Plat vs. Survey: The Key Differences

• A plat shows the big picture—multiple lots within a subdivision.

• A survey shows one lot in detail—its exact boundaries and any improvements.

• A plat is used for subdividing or adjusting multiple properties.

• A survey is used for confirming boundaries, spotting issues, and supporting title insurance coverage.

Both are important—but for different reasons.

Need Help Understanding Plats, Surveys, or Survey Coverage?

Buying property in the St. Louis area doesn’t have to be confusing. At Investors Title Company, we help Missouri buyers, sellers, and agents understand the documents that matter most—so every closing is smooth, accurate, and protected.

Have questions about plats, surveys, or title insurance? Contact our team today. We’re here to help you close with confidence.