When you buy a house, you will inevitably receive what will seem like a mountain of paperwork pertaining to your new digs. One of the documents your title company office might include is a plat map, and it’s chock-full of information about your neighborhood and county.

So what is this map, and why is this information useful to you as a homeowner?

A plat map, also known as a “plat,” shows you how a tract of land is divided into lots in your county. It is drawn to scale and records the land’s size, boundary locations, nearby streets, flood zones, and any easements or rights of way.

A plat map is required if a piece of land is to be subdivided into lots for building homes or if the land is to be made into a public-access location, like a park. This map is also typically included in the paperwork you get when you buy a home.

“Plat maps are drawn by a civil engineer when a development is first created, and approved by the county planning department,” says Casey Fleming, author of “The Loan Guide: How to Get the Best Possible Mortgage.”

“They are used in real estate transactions as part of the title search and insurance. Title records are searched to make sure the seller has the right to convey the property described and the buyer is buying exactly what they think they are buying.”

Plat vs. plot

These words may look and sound alike, but they cannot be used interchangeably. A plat is a map of a land area, usually on the scale of a neighborhood or county township, and a plot is a piece of land used for a single purpose (such as a park or a home).

Essentially, a plat map records the collection of plots that make up a neighborhood.

Not all property is platted

If your deed uses subdivision lot numbers to describe your land, then it’s been platted. But if your deed uses geographical references—also called “metes and bounds”—to describe the size and shape of your property, then it hasn’t been platted.

How to read a this map

One of the first things you’ll notice is that there are lots of numbers on the map. The street number for each lot is listed, and in the middle of each property is a “parcel number” that’s assigned by the county assessor’s office and typically appears in large, bold, underlined type.

Another number is the “builder’s lot number” assigned to the property by the original developer. Along the property lines are numbers that indicate the lot dimensions.

Why you’ll want to read a plat map

Plat maps indicate the east, west, north, and south orientation of the area. That information is helpful if, for example, you want to build a house with the kitchen facing east for morning light, or if you want broad southern exposure for a solar power array.

It’s important to study the plat carefully to look for any easements that exist on the property. If a portion of your land is legally designated as an easement, people could be entitled to use it based on the type of easement it is.

A typical scenario might involve a right of way that your city has established for a future roadway.

This type of easement might influence whether or not you buy the property. You probably wouldn’t want to wake up one morning to the sound of a bulldozer legally cutting through your backyard!

Plat maps are especially useful to help visualize odd-shaped lots, their proximity to neighbors, and how you can use the land.

Have your land surveyed

Plats aren’t necessarily perfect. In fact, they often state that the lot dimensions on the map are “approximate.”

For strict establishment of your boundary lines, you’ll need to have a survey completed by licensed professionals. A typical residential lot survey costs $300 to $1,000; difficult terrain, with creeks or steep hillsides, will add to the cost.

“The reason you get a survey is because a lot of improvements may have taken place on some of these plats,” says Jason Shepherd, co-founder of Atlas Real Estate Group. “You would want a survey to make sure that the parcel and the (new) house sit on the plat where you want it to be and, most importantly, where it is legal.”

It’s a good idea for prospective buyers to check out the lot dimensions and make sure they match the lot size listed by the real estate agent.