You can tell when it is getting to the time when you need to replace your existing patio door when you notice gaps between the two doors or between the doors and the frame. These gaps mean your door has lost its energy efficiency and air can easily pass through your door. If these gaps are large enough, snow and rain may also be able to seep through and cause damage to your walls and flooring.

If your door is difficult to operate is also another sign that you should be looking to replace your patio door. The doors should glide easily across its tracks, if it requires significant force to open or close your door, it means that your tracks are either worn or damaged or that the door rollers are damaged.