Boundary lines are the imaginary borders of a piece of land. There are four basic boundary lines found on residential property lots: land, water, air, and sub-surface. Each type of boundary line has a set of rules that dictate how they are determined.

How Are Land Boundary Lines Determined?

Usually property boundaries are defined by the property's deed. There are cases, however, where the deed can be superseded, such as: 

  • Agreed Boundary Line - When there is uncertainty as to the true boundary line, and no reasonable way of determining it, the parties may agree to set a new boundary line
  • Acquiescence - The act of implying consent to boundary line by remaining silent
  • Estoppel - When a prior legal decision is determinative of a current property dispute
  • Adverse Possession - The laws of adverse possession allow a person to obtain title to land by simply using the land for a period of time specified by state and federal laws

How Are Water Boundary Lines Determined?

Two common law rules address the issue of water boundaries that may move over time. Accretion occurs when the location of a water boundary moves slowly due to gradual buildup of soil; a property line shifts with accretion. However, avulsion occurs if there is a sudden change in the location of such a water boundary, in which case the property line is deemed not to have moved.

How Are Air Boundary Lines Determined?

It is increasingly accepted that a landowner owns only the airspace that is reasonably necessary for the use or enjoyment of the land, not all the airspace above the land.

How Are Sub-Surface Rights Established?

The traditional rule was that the ownership of land included ownership of everything underneath the land surface down to the center of the earth. But as an exception the rule, the surface owner does not necessarily own any subsurface oil and gas. In some states oil belongs to the first person to capture it through extraction.

Should I Contact an Attorney About My Boundary Line Dispute?

If you are uncertain as to your property's boundary line, are attempting to recognize a new boundary line, or are in a dispute about a current boundary line, you may find the counsel of a real property attorney to be very helpful. Because of the complicated nature of this field of law, a real property lawyer can answer important questions and give advice on what is the best way to proceed with your case.