When Dave Sarti heads for the backyard of a nondescript blue house in Seattle's Central District, it isn't to do some grilling or gardening. It's to go home. A few years ago, Sarti bought a piece of the blue house's lot and built a little house for himself. A skinny red house. The cube-shaped dwelling is 800 square feet and cost $180,000 to erect. To Sarti's way of thinking, he is living large--in close proximity to downtown at a reasonable price.

The notion of wedging small houses into available small spaces is not unique to Seattle. Urban planners in a number of cities are keen on the idea, which represents an antidote to huge houses on large lots that gobble up land and contribute to sprawl. Indeed, not everyone wants to live in a McMansion. Smaller places are perfect for empty nesters, older couples looking to downsize and single professionals trying to buy their first piece of property. Diminutive dwellings can provide affordable quarters in urban areas where land prices have soared.

In the 1990s, Seattle undertook a demonstration project that permitted people to build small houses in single-family areas that normally wouldn't allow them. That led to some new carriage houses, cottage housing and mother-in-law flats--all types of small, detached residences on little lots. Despite showing that these could be "great projects," Diane Sugimura, director of the Department of Planning and Development, says many citizens "fear it will start becoming two houses on every lot. But that won't happen because most people don't want a second house on their lot."

Not everyone is afraid of density. Residents in Southeast Seattle, for example, pushed for the opportunity to build small. But not all skinny houses are created equal. Seattle has had its share of ugly ones. "We were getting these three-story, birdhouse-looking things," says Sugimura. So the city changed its height standards to prevent the precarious, aviary look.

In Portland, Oregon, which actively promotes infill housing as a result of its Urban Growth Boundary, many small homes being built by developers barely met minimum building code and design standards. "These were completely out of character, dimension and aesthetics in the neighborhoods where they were built," says city commissioner Randy Leonard. So in 2004, the Bureau of Development Services sponsored an international design competition that selected 49 single-family, detached-home plans as suitable for narrow lots. Two have been approved as "permit-ready."

Most recently, the skinny-house debate has flared up in Boise, Idaho, where landowners have been splitting off 25-foot portions that used to be side- or backyards and selling them to people who want to build on them. Some residents on these blocks, however, are complaining about how they might affect property values. "The concern is that it changes the character of the neighborhood," says city planning director Hal Simmons. "They're taller, use more of the site and look different from the other houses."

The city is split over the issue. On the one hand, infill houses in developed areas bring new investment to neighborhoods that were somewhat neglected. Families and professionals settling in tend to bring back or strengthen both public and private services. Broken sidewalks get repaired. But past construction practices were poor and the units didn't look good. They had vinyl siding and minimum window openings. "They were bare-bones boxes," Simmons says. They ended up becoming cheap rentals, defeating the city's desire to achieve affordable housing.

Borrowing from Portland's documents, Boise put in place emergency standards on height, size and architectural details so that neighbors would find them more acceptable. In the past year, the city has approved about 150 of these houses. Builders are required to use quality materials that complement the look of the neighborhood. Open space is required in the backyard. And unless the houses are next to a two-story house, they can only be one-and-a-half stories high. If builders want to construct two-story homes, they can build a basement with windows or a second story within the volume of the roof by using dormers.