Let's examine a common scenario that in which property owners worry that they are falling victim to adverse possession:
A few years ago, my neighbors built a wooden fence around their home. We've always had a great relationship. But my wife and I just realized that their fence was built three feet onto our property. The neighbors don't actually use those three feet, but now we can no longer access them. I've heard that the neighbors might now be able to claim ownership over that land through adverse possession. Can they really take our land like that?
To understand this issue, we'll need to look at:
The doctrine of adverse possession provides a means by which a trespasser, often a neighbor, can establish title to a piece of property. To acquire title to property by adverse possession, the law of most states says that the possession must be actual, notorious and open to the world, hostile to the interests of the true owner, exclusive, and continuous for the statutory period.
The precise statutory period during which the person must control the land varies from one state to another, but is often between seven and 20 years. A trespasser would need to go to court and prove each element of that claim.
In the sample situation above, neighbors have constructed their fence in the light of day, for anyone to see, and are occupying those three feet of land exclusively. This means that their use of the property probably meets the actual, hostile, open, and exclusive requirements. The fact that they're not literally, actively "using" the three feet of land would have no effect on the "actual" part of the analysis, since they've effectively taken control of the strip with the fence.
Their problem in their making a claim for adverse possession, however, is that they haven't yet met the required statutory period. No jurisdiction would grant adverse possession to someone after occupying a strip of land for only three years.
But even if the neighbors would lose a current court fight over title to the land (for the next several years, at least), the original landowners face a practical problem: Eventually, they'll want to sell the home, and every square foot of property will count. Sooner or later, the neighbor who built the fence over the line will meet the statutory requirement and be able to legally claim title. Even if the original owner doesn't particularly care about using that strip of land, there is a great deal of value on the line.
Sure, the original property owners could hire a lawyer and sue the neighbor for trespass, but this would likely destroy their cordial relationship.
A far better solution would be for them to have a conversation to see whether the neighbor would be open to exploring the cost or difficulty of simply moving the fence. They might be embarrassed to learn that they built the fence in the wrong place, and offer to move it at their expense.
If the cost of moving the fence is prohibitively expensive, and the original owners don't particularly care about using those three feet of land, there's another way to prevent the neighbor from being able to eventually claim adverse possession. It's by giving explicit permission to "borrow" that strip of land. Remember, for a trespasser to establish a legal claim of adverse possession, their possession must be hostile to the original owner's interests. If the possession is with permission then, by definition, it cannot be hostile.
One of the most common ways to establish that someone gave neighbors permission is to have them sign a simple rental agreement. For a nominal amount (say, $15 per year), they can keep their fence over the property line and use that three-foot strip. So, if in 20 years, the neighbors run to court to claim adverse possession, the original owners will be able to defeat their claim by introducing evidence of the rental agreement and annual payments. This shows that they cannot meet the hostility requirement to gain title.
Of course, it would be best to write that agreement with a limited term, so that it can readily be undone if and when the original owner sells the property, at which time the purchasers might be less interested in granting the neighbors such permission. Nolo's free sample rental agreement provides for this.