Pergolas can be built in a variety of ways and with different materials. Most often, pergolas are wide open structures, with four support beams and no walls and roof. Their primary purpose is to create a decorative focal point. They are not used to shelter out the sun and unwanted elements. The traditional pergola consists of a lattice roof; however, with the ever-changing styles, wood has become popular. Vinyl can offer a universal design and is less expensive. Steel will hold up in harsh weather and will last the longest. If a solid roof is required, gabled or pitched is recommended. This provides for the natural runoff of water.