The fence belongs to someone... you need to check your survey.
Surveys do not show ownership. Only location.
That's not to say you can't go in on a new fence together with a neighbor, but they have no obligation to do so..
just as you wouldn't have to maintain or replace a fence that isn't technically on your property.
An "encroachment" is the property (fences, patios) of one, on the land of another. Again, location does not absolve ownership. But, If the fence existed when you moved in, before any current homeowners moved in, who knows what rights transferred to whom.
Also every town or municipality has rules that govern where exactly a fence should be placed. For instance in our town...a fence is generally placed 6 inches "in" to your property. A property line..is
an imaginary line. Not imaginary, invisible but it can be determined.
just as much yours as your neighbors.
only if the legal descriptions of each parcel describe a contiguous line. Sometimes there are gaps and sometimes there are
overlaps!!! Therefore, it's safer to place your fence a few inches into your own property. Also fences in our town are supposed to have the "good" side ( if it's not a two sided fence) to your neighbor. Considered a "good neighbor" policy. Yet in the county my mom lives in you can put the fence anyway you like. You may not be a good neighbor though!
All this aside, we have "gone in on" a fence with my neighbor that bordered both our properties. We put in a new PVC fence with a lattice top to replace an old wood one. This benefited both of us, as it was nice to look at from both sides, and we split the cost.