This depends mainly on how well the posts were installed and what type of wood was used to build the gate in the first place. Softwoods have a life expectancy of up to 15 years but can last slightly longer with regular maintenance and waterproofing treatments. By contrast, hardwoods can last up to 30 years with little care, so you may avoid costly replacements by spending a little more upfront.

To choose where to add a fence gate, know where fence gates shouldn’t go. For example, you should avoid placing gates over low spots on the ground where water can collect and form muddy puddles. Many ranchers install gates at the corner of a fence. Certain gate placements may also be required depending on the type of gate latch you use.

A fence gate can sag for several reasons. The issue often stems from the hardware, such as damaged or bent hinges, or loose screws that can no longer support the gate's weight. The gate frame itself might also have come out of square due to failing supports. Alternatively, the problem may not be the gate but the supporting fence post, which could be leaning or out of place. In many cases, fixing a sagging gate is as simple as tightening the hinge screws or upgrading to more robust hinges.

Who pays for a new fence between neighbors depends on its location relative to the property line. If you build the fence entirely on your property, you are solely responsible for the costs of installation, maintenance, and repair. If the fence is built directly on the property line, both neighbors are typically responsible for the costs. In this case, it is essential to consult with your neighbor beforehand to agree on a plan for payment. While you should always inform your neighbor of your plans in advance, you generally cannot force them to contribute financially unless there are specific local laws, such as in California, where both parties might be responsible for costs unless a different agreement exists. It's a good idea to get a property line survey to know the exact boundaries before building.