When considering a vinyl fence some things that can vary greatly from company to company are as follows….
The profile (boards, rails & posts) thickness and additives that go into the mixture to make them are the biggest differences in pricing from company to company. Most professional fence companies sell products that meet or exceed ASTM F-964-94. But not all fence companies are professional fence companies.
Posts: The average post wall thickness is from .135 to .150, some companies are selling posts with a wall thickness as thin as .120. Our practice as a company is to use .135 wall thickness on fences up to 4 1/2′ to 8′ high. Minimum depth in the ground for vinyl posts is as follows: 24″ for fences up to 3 1/2′ high, 30″ in the ground for fences 4′ to 4 1/2′ high, 36″ for fences 5′ high and 6′ high and 40″ for fences 7′ high to 8′ high. All posts should be st with concrete with at least 6″ of dirt backfill over the top to help prevent frost heave.
Rails: The horizontal pieces that hold up the fencing. A privacy fence should have rails with a minimum outside dimension of 1 1/2″ x 5 1/2″, at least 2 internal webs and an aluminum insert that runs the full length of the section. The rails should have a minimum wall thickness of .090. Some companies are usinf rails as thin as .050 with out inserts which allows the fence to sag and bow in the wind.
Boards: For privacy fence the boards should be tongue and grove (interlocking) and protrude far enough into the cross rails to prevent them from coming out of the rails. They should have a minimum wall thickness of .050. A board thinner than this is in great danger of bowing in a high wind (a high wind is considered to be any gust or sustained wind over 30 mph) and coming out of the fence rails possibly causing damage or injuries. Some companies are using boards with a wall thickness as think as .030. Never should the infill or the boards in your fence be 1 solid piece on material like some of the offerings from the box stores. (see Expansion/Contraction)
Additives: All vinyl fences should have the following additives correctly added to the mixtures that make up the vinyl for the vinyl fences. Impact Modifiers for cold weather and TitaniumDioxide for the U.V protection. If you do not have the proper amount of Impact Modifiers for cold weather you will break boards or out holes in them with any object in a temperature below 32 degrees. If you do not have the proper amount of Titanium Dioxide your fence will start to chalk and degrade after the first couple of months (just like those white chairs from drug stores).
Hardware: All hardware attached to a vinyl fence should be at a minimum made from nylon but preferably powder coated stainless steel. This is so it does not rust or corrode and stain your new fence. All of the hinge posts should have an aluminum I-beam (or insert) that goes inside the post to attach the hinges to. An I-beam inside the latch post is not strictly needed but it can be added for an extra charge if you wish.
Expansions/Contraction: Your new vinyl fence will expand and contract with the weather this is a normal process. During this process the boards on your fence will actually slide in the rails on your privacy fence by as much as 1/4″. With fuse bonded sections this process actually breaks the bond between the boards and rails over a short period of time. With a solid 1 piece infill the process will actually crack the infill panel.
Gates: Gates should be of sturdy construction and come pre-made from the supplier. There are 2 types of pre-made gates the first one is a pocketed type, with a 4″ upright post on each side of the gate (this is the only style we use). The second is the welded style gate; our experience with this style is that the welds tend to fail on a regular basis which means the gates have to be replaced. Never should your gate be made with an adapter kit, this turns a section of fence into your gate.
Box Stores: Box Stores sell a vinyl panel that is fuse-bonded or glued together that attaches to the posts with brackets. All professional fence companies consider this product to be something other than fencing.