What's the Deal With PVC Trim?
The PVC (polyvinyl chloride) trim we're talking about is also referred to as cellular PVC. It's PVC all the way through. Don't confuse it with high-density rigid polyurethane or PVC-coated products. While they too are highly durable and low maintenance, their installation techniques are different. PVC is a form of plastic that's used in a hundred different ways, including for plumbing pipes.
The trim comes in various thicknesses and widths, but it's most often sold in common sizes similar to other wood trim products. Some companies offer material that has an embossed wood grain side and a smooth side. There are dozens of profiles to choose from: bead board, skirt board, tongue and groove, quarter round, brick molding, coves, crowns, just to name a few. You can even get it in sheets like plywood.
The home center near you might stock only 8-ft. boards in a few of the most popular widths, so you'll likely have to special-order longer lengths and the specialty profiles and moldings. The price is the biggest downside to PVC—it's expensive.