In addition to railing and fencing, vinyl manufacturers sometimes make or sell porch posts or porch columns. Here’s an overview of posts, columns, and what exactly goes into making them.
What’s the difference between posts and columns?
Generally, posts are used in conjunction with railing and are designed to have the appearance of turned wood. Posts are slimmer than thicker vinyl porch columns. Columns are smooth and can be used with railing or standing alone.
Posts usually come in a variety of styles to pair with railing and match the look of a home. Railing is fastened to porch posts in the same way you’d fasten it to a standard railing post.
Vinyl columns also come in several styles, but typically with fewer choices than posts. To fasten railing to columns, installers use a wedge. One end is designed to rest against the round column and the other end looks like a traditional bracket that holds the railing.
How are they made?
Vinyl products are usually made through an extrusion process, where powdered resin is heated and then pushed through an extrusion die to create a shape. Porch posts and porch columns are extruded as long tubes of vinyl and cooled. Then, the vinyl tube is reheated to soften it and placed in a blow mold, where air blowing through it gives it the shape of the mold and cools it immediately, hardening it into its final shape.
To see a demonstration, you can check out the Superior company video featuring a blow molding process (around the 1:00m mark). 
Can they support a porch roof?
A vinyl post alone does not have the strength to support a roof. They are essentially plastic, after all. The good news is, adding an interior aluminum support channel makes it possible for a post or column to support a roof or overhang. Superior’s vinyl posts with aluminum channels can support up to 26,000 pounds depending on the style. Superior columns can support up to 18,000 pounds.
Vinyl posts without these interior aluminum supports can be used decoratively but should not be used for any substantial weight bearing.
Why should I use vinyl instead of wood?
Wooden porch railing and posts have some advantages in both cost and appearance, but vinyl is easier to maintain, easier to keep clean, and homeowners can be surprised by how impressive it appears when installed.
