Manufacturers’ prices do not always include delivery fees, and there can be other costs, including site preparation, foundation work and installation of electric, water and sewer services. “You have to go into this with open eyes,” said Jay Shafer, owner of the Tumbleweed Tiny House Company. “Zoning laws, land covenants, building permits, restrictions and codes vary within states and across the country, and these impact what has to be done at the site, and how.”

Image Scott and Lisa McGlassons 700-square-foot weeHouse from Alchemy Architects in northern Minnesota. Credit... T.C. Worley for The New York TImes

For $90,000 in 2004, Scott McGlasson, 40, owner of Woodsport, a custom furniture design studio in Minneapolis, and his wife, Lisa, a human resources coordinator, bought a 700-square-foot weeHouse by Alchemy Architects. It has plumbing, tall glass doors, Andersen windows, laminate flooring, recessed lighting and Ikea cabinets. It is comfortable and attractive. “But people confuse prefab with inexpensive,” Mr. McGlasson said. “On a middle-class budget, this was doable, but not easy.” They bought the land — a small lot on Lake Pequaywan in northern Minnesota — in 2002 for $80,000. It already had a septic system, a well and access to utilities.

One rectangular module serves as the main floor; above it is an additional square module that serves as a second bedroom, which must be entered from outdoors via a ship’s ladder. Guests love it because it’s separate from the rest of the house. “And because they can lock out our three kids,” Mr. McGlasson said.

Still, it’s hard to resist doing the math. Five people sharing about 700 square feet has to present challenges — especially when three of those people are still growing. To make the most efficient use of the space, Mr. McGlasson designed and built much of the furniture, some with birch from the surrounding forest. He also added a free-standing sauna and a deck for outdoor living. “But when friends come, we’re pretty packed in,” he said. The trade-off is that when the time comes to leave, they just sweep it out and go. “We’re here to swim, fish, hike and cook,” Mr. McGlasson said. “If we wanted all the conveniences of home, we’d be there.”

Living tiny, however, does not require deprivation, thanks to modern technology. Gregory Johnson, president of the Small House Society, who lives in a 140-square-foot house in Iowa, noted that people once needed “a stereo system, countless LPs or CDs, photo albums and a small library of books.” Now, everything can take up no more space than a laptop or an iPod.

Stephanie Arado, a Minnesota Orchestra violinist, said that it took living in a tiny house to learn how little space she really needed. For about $45,000, she bought a 392-square-foot weeHouse with no electricity and no bathroom as the solution to a siting problem on her 32 acres in western Wisconsin. Ms. Arado, who has two children, planned to use the tiny house as a springboard to building something bigger.

But four years have passed, and she now has no intention of supersizing. “Something happened,” Ms. Arado said. “I started to see the beauty in how it works.” There is a queen-size bed for her and a bunk for her two children. When friends visit, sleeping pads and cots are pulled out. “The glass walls make the house feel much bigger than it is,” she said. “People are surprised to hear it’s only 14 feet wide.”