If you’re a purist and prefer natural materials for exterior applications, you can add another wood option to your list. Accoya is made from a process that increases wood’s acetyl molecules, making it more durable and dimensionally stable. The UV-resistant boards can be used for a variety of applications including siding and decking. Cost: $3.50 to $4.80 per linear foot. East Teak Fine Hardwoods. 214-751-8988. www.certifiedhardwoods.com.