An easement is the right to use or limit use of part or all of someone else's property for a specific purpose. Easements can be for an underground electrical or sewer line, egress to someone else's property for a driveway, to prohibit the property owner from doing something like building a structure that would block a view, or any number of other purposes. Whether an easement affects the value of the property will depend on its extent and purpose.
Purposes for easements are innumerable. Common easements include airspace accommodating a roof gutter, eave overhang, underground utility lines, and access paths. Some written easements are quantitatively defined, such as a utility line path 2 feet in circumference 3 feet below grade. Others are described only by purpose: A path to access adjacent property. A negative easement is a right to prevent the property owner from undertaking a specific action. An example is a heritage easement that prevents a property owner from demolishing an historic building.
Types of Easements
Easements are often classified into one of two categories: in appurtenant or in gross. An easement in appurtenant benefits a specific, usually adjacent, property. An example is a driveway leading through one property to get to another. An easement in gross benefits an individual or groups of individuals who do not own another property that benefits. An example would be a boat ramp on someone's property used by many people to gain access to a public lake. Easements are often recorded, but do not have to be. A prescriptive easement is one that developed by use over a long period of time that was not prevented by the land owner. An example would be a large land owner who knows a small swath of his land is being used as a path to a lake or as a shortcut to a road but does nothing to stop the use. After some period of time (the time varies from state to state), the users of this path develop the prescriptive easement, which cannot then be taken away by the property owner. Prescriptive easements are often not recorded.
The value of an easement depends on its location, purpose and use. If a neighbor's gutter overhangs your property by one inch in an area in which you would not be able to build due to zoning or building prohibitions, its value is likely to be negligible. But if an easement is described on your deed as a 20-foot-wide path through the center of your property -- preventing you from ever building on the lot -- its value would be significant. An easement can be appraised, just like any other aspect of a property. Easements can be bought and sold. Some state and local governments have created programs that allow property owners to donate easements for open space and cultural resources, allowing the owner to claim a charitable contribution or claim a tax credit.
Some mortgage promissory notes prevent a property owner from selling or donating an easement without prior approval from the mortgage lender. This is because lenders are worried that an easement might affect the value of the property to the extent that the remaining equity would be insufficient to support the loan.