Although technically not considered rooms, most outdoor spaces added to homes are room-size or larger and have the same basic elements-and some of the same features and amenities-as regular room additions. All require a proper foundation and solid floor construction, and many involve some type of cover plus a sturdy structure to support it. In short, an outdoor living room has everything that indoor rooms have except solid exterior walls. Therefore, they require a similar amount of planning, labor and expense to do a good job of boosting your home's livability and value.
The simplest open-air "room" is a single-level deck or terrace with no cover. However, it's also the most limited in terms of livability because it provides the least protection from the elements. Adding a cover, such as a trellis or awning, boosts livability considerably but also introduces extra structural and aesthetic considerations. A full-fledged open porch, complete with posts, railings and a pitched roof, offers a sense of enclosure and protection similar to an indoor room. Adding screen panels heightens this sense of enclosure-and allows you to enjoy the space without having to arm yourself with flyswatters and bug spray.
When planning an outdoor living room for your deck, patio or yard, taking climate conditions into account seems obvious. Yet it's easy to get carried away by the romance of a porch or deck design and end up with an outdoor room that's uncomfortable or uninviting much of the time and, therefore, a poor investment. For instance, if you live in a temperate climate where it's too hot to sit for long periods of time in full sun but too chilly to sit in deep shade, neither an open deck nor a solid-roof porch is likely to be a sensible option for your outdoor living room. Instead, you probably should aim for a structure that provides dappled or tempered shade, such as a trellis or some type of translucent canopy. If you live in a cool climate or a heavily shaded neighborhood and are planning to add a porch, you may want your outdoor living room to include skylights or a trellis section in the roof design to avoid creating a space that feels cold or oppressively dark. And if your climate changes from day to day or season to season, consider a hybrid design-part open deck, part trellis-covered deck, and part covered porch. For more on designing a porch, go to Porch Pointers.
Other factors to keep in mind as you picture your home's perfect outdoor room are function and maintenance. Will you need space to seat several people, or just one or two? Will you want an area for dining as well as for seating? Will you need space in the addition to store furniture and accessories when they're not in use? One mistake often made with porches and decks is designing the space too narrow for a comfortable seating arrangement. (A minimum depth for porch seating plus a traffic lane is approximately 7 feet.) Another common mistake is including details or materials that require labor-intensive maintenance. Gingerbread, fretwork, lattice, spindles and other trimmings that add great charm to decks, porches and patios can also be big headaches, unless you choose the right materials and finishes. Fortunately, painted wood is no longer the only option for such decorative elements in outdoor rooms (paint is an extremely high-maintenance finish for exterior surfaces); you can instead get them in stained or naturally weathered wood, or in molded plastic versions that require no painting or staining.