The most important tips for installing vinyl fence posts are to measure the distance between posts accurately, and to sink the posts at the right depth. Unlike wood or even metal posts, they cannot be cut or shimmed if the distances are measured inaccurately. Vinyl posts are prefabricated, meaning they come in specific dimensions right from the factory, so if a post is set too high, one cannot simply cut off the top like he or she could on a wood fence. Since vinyl fences expand and contract with the weather, the vinyl fence posts must be set at the correct distance from each other to prevent cracking or buckling.
The distance between vinyl fence posts needs to be carefully measured. Vinyl fence panels will flex as the weather changes, and if the posts are too close together, the panels can warp or crack. If they are too far apart, the panels may work loose and fall out. If the builder has purchased a kit, instructions are often included to specify the tolerances within which the posts must be placed. If no instructions are included, be sure to consult a professional or research installation methods.
Like other types of posts, vinyl fence posts should be secured in the ground with concrete. It is vital that the hole be dug below the frost line. This will prevent the posts from being pushed out of the ground once frost settles in. Concrete should be poured into the hole with the post in place, and the hole should be wider at its bottom than at its top. This prevents any upward motion during frost heaves. It may be a wise idea to make sure the top of the poured concrete has an arch to it to prevent water from pooling on top. Pooled water can seep into concrete, causing cracks later on down the line.
Vinyl fence posts are often sold without a top so the customer can customize the posts to his or her liking. Post caps range from the very simple to the elaborately decorative, and some post caps even have lights in them. Choose a post cap that fits the aesthetic of the yard, and remember that choosing a cap with a light inside means running wires to an electrical outlet. This adds time and effort to the installation process, but if the fence runs along a walkway or driveway, lights may be worth the extra time and effort.