Property boundary lines are the imaginary borders of a piece of land. They are important because they allow a person to determine what property belongs to them both physically and on their deed documents.

They are also helpful for when there is a dispute between neighbors regarding whether one of the parties is infringing on the other party’s land.

For example, if Neighbor A wants to remove a tree that they believe is on their land, but it actually is within Neighbor B’s boundary lines who wants to keep the tree, then Neighbor B can raise a legal challenge against Neighbor A to stop removal.

In general, there are four basic boundary lines found on residential property lots. These are land, water, air, and subsurface. Each type of boundary line has a different set of rules to follow that describe how a person can determine them.

How are Land Boundary Lines Determined?

Land boundary lines are the type of property boundary lines that most people think of when there is a dispute. Normally, land boundary lines are defined by the deed to the property.

There are certain instances that arise, however, where there may have been an error with the deed or naturally occurring circumstances that led to the boundary line disappearing (e.g., mudslides slightly moving a fence that held the original land boundary lines).

In such a case, the deed may be challenged and can be superseded by the following actions:

  • Agreed-to Boundary Line: When there is uncertainty as to the true boundary line and no reasonable way to determine where it lies, the parties may agree to set a new boundary line; 
  • Acquiescence: This occurs when a party implies consent by remaining silent about the actual boundary line. For example, if a person grows their garden onto their neighbor’s property, but the neighbor does not object to this action, then they have implied consent to the neighbor possibly owning up to that line of the property;
  • Estoppel: Estoppel can be used where a prior legal decision determines the outcome of a current property dispute. For instance, if a prior case already defined the proper land boundary lines, then the current dispute can follow the lines described in that case; and
  • Adverse Possession: The laws of adverse possession enable a person to obtain title to land by simply using it for the period of time specified by both state and federal laws.

How are Water Boundary Lines Determined?

There are two common law rules that address the issue of water boundary lines that may have moved over time. They include the following:

  • Accretion: This occurs when the location of a water boundary line moves slowly due to the gradual buildup of soil. It is then said that the property line has shifted due to accretion. This usually means that the landowner has acquired an increase in land and has a right to the additional boundaries created.
    • For example, if a house was originally closer to the shoreline of an ocean or lake, but over time there was a gradual increase of sand buildup because of the waves that moved the house farther away from the water, then the land in front of the house can be considered an accretion of property. 
  • Avulsion: In contrast, avulsion is a sudden change in the location of a water boundary. This can happen when there is a storm that floods the property and removes parts of the soil that were originally considered part of the land. If this occurs, then the initial property line is deemed not to have moved.

How are Air Boundary Lines Determined?

It has become increasingly accepted that a landowner only owns the portion of airspace that is reasonably necessary for the use of or enjoyment of their land. The airspace above the land is usually not included in the description of air boundary lines.

How are Subsurface Rights Established?

The traditional rule was that the ownership of land included ownership of everything underneath the land surface all the way down to the center of the earth. Now, as an exception to this rule, the surface owner does not necessarily own everything below the land.

This usually means that any subsurface materials, such as oil and gas, may not belong to the surface owner. Depending on the laws of the state, some state statutes assert that oil belongs to the first person to capture it through a process known as extraction.

Should I Contact an Attorney About My Boundary Line Dispute?

If you are uncertain as to your property’s true boundary lines, are attempting to recognize a new boundary line, or are involved in a dispute over current boundary lines, hiring a property attorney for legal advice could prove to be very beneficial to your case.

A local property attorney will be able to understand the complexities of title ownership and boundary line disputes. They also will know which laws apply in your particular jurisdiction and the best way to resolve your issues.

Not all legal actions necessarily need to end up in court, but whether they do or are instead settled using a method of alternative dispute resolution, a qualified property attorney will be able to provide assistance regardless.