In general, you can categorize the types of vinyl siding trim by their function and shape. J- channel, F- trim, H- mold and corner post are some of the most basic and common types, but you may also be interested in door surround, crown molding and undersill.
All types of vinyl siding trim are meant to surround a window or other opening, hide the edges of the panels and color-coordinate with the rest of the house.
Identifying vinyl trim is relatively easy, especially for the "alphabet" profiles. J-channel is in the form of a squared-off letter J, F-channel trim is shaped like a letter F and H-mold resembles a letter H.
Outside corner post, or OSCP, is easily identified because it looks as if it would "hug" the corner of a wall and appears as a solid post. Inside corner post, or ISCP, fits where two walls meet and face each other, so one of the nailing hems is placed at the opposite angle from its cousin's.
Just as there are many different sizes of panels to choose from, vinyl siding trim comes in many choices. J-channel, for instance, must have a large enough gap to accept the end of a panel, but not so large that empty space is visible. Therefore, it is offered by most companies in sizes from a half inch up to 1 1/2 inches, in 1/8-inch increments. Corner post ranges from 1 3/4 inches wide to 4 inches or more.
Width is not the end of it, though. Most corner post is 10 feet long, but some products are made for a specific purpose and packaged shorter or longer. Vinyl trim lengths vary from the 6-foot, 6-inch corner post for sheds to the 20-foot-long window and door surround. Some manufacturers will even allow you to order custom lengths to suit your project.
Most vinyl siding manufacturers offer color choices that match the panels in their trim profiles. This offers the homeowner or contractor an almost limitless range of options to choose from when designing the overall color scheme of the house. If you want green siding and red trim, you can do that. A quick walk-through of Anytown, U.S.A., will reveal a gross overrepresentation of white trim; if it's done tastefully, bold color combinations can make the difference between a nice-looking house and a stunning home that stands out from the rest.
Last, but not least, vinyl manufacturers offer a wide variety of embossing patterns to mimic different wood grains or even stone. The pebble emboss pattern (sometimes called smooth or stone) mimics the texture of hewn and smoothed granite or sandstone. Wood grain patterns range from Soft Maple to Deep Oak to Cedar, depending on the homeowner's preference. You can even get some trim profiles with a brushed aluminum look to them.