Fabrics are an excellent option for a deck covering. A canopy can be retractable so you need to bring it out only when needed. However, a retractable option is not the only way to use fabric; you may prefer a style that acts as a covering on a permanent basis. When choosing fabric, you will need to purchase a material that can stand up to the heat of the sun and retain its color. Outdoor fabric is offered in many styles, including patterns, solids and stripes. Outdoor fabrics are purchased by the yard and range in cost from as low as $8.00 a yard to well over $20.00 a yard as of 2011.
A wood covering is an attractive option for a deck covering. For filtered sun, a trellis style with overlapping lengths of narrow wood boards allows some sun in but keeps exposure to a minimum. Plants can be trained to grow up into a trellis, adding even more shading. The wood should be treated to handle the effects of harsh weather and direct sun. A solid wood covering can be built if the function of the covering is to keep sun completely off the deck.
Some homeowners use their deck as an addition to indoor living space. If this is the space you are working on, metal roofing would be a good choice. A metal roof will protect you from the elements, does not have to be sealed and, unlike wood, metal is waterproof.
As an alternative to building onto the deck, consider using nature for your covering. Plants can be trained to grow over areas and act as a sun filter. While this will not protect you from all the elements, it will keep rain, snow and sun to a minimum. Bougainvillea, grape vines or potato vine are a few suggestions for plants that grow well as coverings. More maintenance is involved with this option than the others because, unlike the other choices, this covering will grow. In the fall you should trim down some of the summer growth to help keep its shape.