My first experience with decks was the two we didn't have. My dad built a house with two doors that opened into space. One was supposed to lead to a deck that wrapped around the back of the house with a view of the ocean and a barbeque next to an outdoor table. This door opened ten feet off the ground and we kept it bolted shut. The second door was intended to lead into a glassed-in porch full of potted herbs we could pick year round. We hung a curtain over the window in that door and rarely thought of it.

Perhaps because of this constant childhood tease, I particularly admire well-built decks and I often dream about how good they can be: far from the madding crowd, close enough to get a new book if I need one, or refill my glass from my very own fridge, or play host in a setting more personal than any restaurant.

"These places are about refuge from this chaotic world in which we function," says Robert George, who has been creating outdoor living spaces for 20 years. "If you have the means to create these spaces, why not have them be the epitome of simplicity and beauty?"

The deck has become what the front porch once was: the American homes' most common outdoor living space. By one estimate, decks or deck-like structures are found in 85 percent of single-family homes in the US. But homes have featured outdoor space for ages. Putnam County architect Robert Brown Butler looks to ancient times, when the Greek "ambulatory" and Roman atrium provided practical and economical living space that took advantage of the Mediterranean climate. The deck is almost certainly an evolution of the terrace, a flat platform usually of raised earth extending from a home, often with vertical or sloping sides. A wooden deck mimics the effect; elevated aboveground, a deck can stand above hilly terrain and be joined directly to the house at any height to be at floor level - and doesn't require moving earth.

Another clue to the deck's popularity is found in the shift in American society. Homes once sat close to the roadways to facilitate social encounters, but today we have set-back ordinances that require homes to be sited 40 to 60 feet from the road. Architectural technology professor Stacey Moegenburg points to the car as the catalyst: "Once automobiles became ubiquitous, the social interaction on the street side of the house was altered, at least in suburbia and exurbia." Furthermore, she says, as the garage moved from the rear of the property to the front of the house as a status symbol, "the garage usurped the territory traditionally used for porches. Outdoor living spaces were gladly moved to the rear, and more private, side of the house."

In the 1940s and '50s, as the single-family homes came to represent the American dream and a new emphasis was placed on leisure, the amenity of outdoor living space - chiefly the deck, which was economical and easy to build - became something no home could do without.

But slapping an expanse of wood onto an existing house is not always a home improvement. Integrating the deck with the home and into the landscape is key. In fact, creating harmonious transitional space between indoors and out has long interested architects, including Frank Lloyd Wright, for whom residential outdoor spaces were essential. His most famous home, Fallingwater, in western Pennsylvania, features decks cantilevered over a waterfall.

Design and materials are critical to the success of a deck. And then there is maintenance: wooden decks need sweeping, washing, sanding, and sealing. Left untended through wet winters and humid summers, wood mildews, splits, and rots. Abandoned into disrepair, the once proud deck becomes nothing more than exterior storage space for bicycles, tools, and recycling bins.

Robert George says that 90 percent of decks are underused. He refers to those homes in which a guest walks out of the back door onto a deck, then turns around and walks right back in again. There are many reasons for failure: the deck is too big, too small, too squared off, a poor use of space. Ninety percent may be an overstatement, but it underscores the importance of good design.