Since vinyl privacy fence panels are usually sold in 8-meter lengths, the poles should be soldered and 8 feet apart in the middle. If you install shadowbox panels, which are heavier than regular privacy fence panels, additional support may be needed for secure installation. Provide additional support by attaching a block of wood to the post so that it abuts the bottom of the best rails, distributing the weight of the panels over a larger area and several screws. Although this step is not necessary to install traditional panels, it provides additional support for any heavy fence panel.
Hammer a nail near the bottom of an installed corner fence post at the desired level of the bottom of the fence. Let the head of the nail protrude into the wood so you can tie a string to it. Tie the end of a string around the nail. Extend the string to the next corner post, which holds the string taut. Ask an assistant to hang a line level on the string, roughly in the middle, and to allow you to raise or lower the string at the other corner post until the string is level.
Select the entry to specify the string position. Hammer a nail into the post, through the mark. Tie the string to the nail in other corner posts so that the string is taut. Trim the end tag of the string and remove the line level. The level string will be your reference for installing all the fence panels between the corners posts, making sure the rails are level. Measure and cut a 6-inch long piece of 2-by-4 plank for each fence post.