Wright house. Wrong place?

This week a four-bedroom prairie-style house designed by Frank Lloyd Wright and built in 1915 is scheduled to be auctioned off in Chicago. The owner of the building, called the Emil Bach house after its original owner, is putting it up for auction after failing to attract a buyer with an asking price of $1.9 million. The bidding starts at $750,000.

"We've had a lot of interest," says John DeMato, a senior broker at Inland Real Estate Auctions Inc., the company running the auction.

Perhaps the only thing more remarkable than a Frank Lloyd Wright house on the auction block is that the house survives to be sold at all. The Bach house occupies prime real estate only a block from Lake Michigan in a neighborhood where developers have been grabbing up property to build high-rise apartments and condominiums.

But a historical preservation easement more than two decades old forbids whoever owns the home to demolish or even to change it without permission of the Landmarks Preservation Council of Illinois. This protection, experts say, has probably saved it from destruction.

"There's no question in my mind that this building would have been torn down if it wasn't for the landmark easement," says Ronald Scherubel, executive director of the Frank Lloyd Wright Building Conservancy in Chicago. "Developers would love to get their hands on a building like this and put up another condominium or apartment building."

Between 1886 and his death in 1959, Frank Lloyd Wright, the most venerated and, to many people, the greatest American architect, designed more than 500 buildings, most of them houses. About 80 percent of them survive.

Yet, despite a widespread recognition of their cultural value, relatively few of them enjoy the protection that the Bach house has. Indeed, as many as a quarter of Wright's houses may be at risk, says John Payne, a former president of the Wright Building Conservancy and the owner of a Wright house in Glen Ridge, N.J.

"It's a very serious situation," says Mr. Payne. "They're at risk for a whole variety of reasons, not just bad faith. You've got houses poorly adapted to modern needs. You've got houses in changing neighborhoods. They're too fancy for a neighborhood that was once a fancy neighborhood but no longer is."

A half-century after his death, Wright's popularity remains high. His efforts to create a democratic and distinctively American style of architecture continue to excite the imagination of Americans.

Tourists descend on Wright houses as on European cathedrals. Publishers issue field guides to his buildings that come complete with maps and GPS coordinates. Wright's designs can be found on mouse pads, needlework kits, and refrigerator magnets.

Still, the vulnerability of some of his houses became evident last November when the owner of an obscure Wright-designed summer house in Grand Beach, Mich., tore down the house to clear the lakeside lot for a newer and larger house. The Carr summer residence, as it was called, was dilapidated, termite-infested, and uninhabited. And yet to many Wright enthusiasts, tearing down even a minor Wright house seemed almost sacrilegious.

"You wouldn't throw out a Picasso painting just because it wasn't one of his greatest works," says Mr. Scherubel. "So from the perspective of Frank Lloyd Wright houses, even a small cottage is important because it's part of an entire body of work of a great artist."

The demolition of the Carr residence stung especially because it ended a run of nearly three decades without the loss of a Wright building. Although more than 100 of Wright's buildings fell in his lifetime and in the decade and a half after his death, none were known to have been lost since 1974, as both interest in historical preservation and Wright's reputation have risen. In the meantime, millions of dollars were lavished on prominent Wright buildings to restore the architect's original design.

And yet the variety and sheer abundance of Wright's work poses a challenge for preservationists. He designed houses in scores of communities across the country, working for clients ranging from wealthy businessmen to middle-class professionals.

Experts say most of his houses are in good hands today. The Robie house in Chicago, for example, was almost torn down in 1941 and 1957, but today is undergoing an $8 million restoration. The American Institute of Architects has declared it one of the most important buildings in America.

In contrast, the Wynant House in Gary, Ind., a more modest two-story house built in 1916-1917, has teetered on the brink of ruin for more than a decade. A graduate student named Christopher Meyers discovered it 10 years ago in a decaying urban neighborhood not far from the city's famed steel mills. The house is one of Wright's early attempts at affordable housing. But like many houses in Gary, it had been abandoned. A fire had collapsed the second floor into the basement, a hole in the roof let in the rain, and the whole structure was leaning.

Since then Mr. Meyers and others have fought to save the house. They say it represents an early realization of Wright's conviction that even middle-class families ought to be able to live in beautifully designed houses.

"I really believe it's an important tier of Frank Lloyd Wright's work that's been underrecognized," says Meyers.

But the fact that the house is in Gary has frightened off most buyers, and no one has been willing to spend the sums needed to save it, much less to restore it.

Several owners have tried but failed, including a nonprofit organization from Olympia, Wash., that hoped to rent it out to tourists.

"One of the challenges with preservation is how buildings have fared over time," says Sidney Robinson, a professor of architecture at the University of Illinois at Chicago. "It is usually the case that more modest ones have been altered or changed or let go. So they have become vulnerable. They aren't what they once were. That makes preservation doubly difficult."

The opposite problem has endangered even more Wright houses. In wealthier neighborhoods, rising property values and the current demand for larger and larger houses can imperil Wright's more economical designs. Not only do many feel cramped by today's standards, they often lack amenities that modern families expect, such as multiple bathrooms, walk-in closets, and large bedrooms. For most homeowners, no amount of architectural loveliness can compensate for serious practical shortcomings.

"Architecture has this other element," says James O'Gorman, an architectural historian. "It's not just something that enhances life, it serves life. And buildings can run out of usefulness."

On its website, the Frank Lloyd Wright Building Conservancy lists the Wright houses that are for sale, trying to match them with preservation-minded buyers.

The conservancy also works with lawyers, restoration architects, Wright scholars, and an informal network of Wright enthusiasts to keep track of Wright buildings.

Increasingly, it must contend with savvy owners who try to make deals away from public scrutiny.

"People know it's in their interest, if they want to tear down a Wright house, that they do it as quietly as they can," says John Thorpe, a member of the conservancy and a preservation architect who has worked on many Wright houses.

Even before the Carr cottage was demolished, there were several close calls. The Glasner house in Glencoe, a wealthy Chicago suburb, was nearly demolished two years ago to make room for a larger house. The owner at the time called it a "million-dollar house in a $5 million neighborhood." But preservationists rallied, and after a long search, found a wealthy buyer who was willing to save the house.

Sometimes it seems almost impossible to give away a Wright house. Seven years ago the Historical Landmarks Foundation of Indiana advertised the Wynant house for just $55,000. Hundreds of people called, but almost everyone wanted to move the house out of Gary, which the foundation forbade.

Sometimes, though, moving a Wright house is the only way to save it. Last year the Wright Building Conservancy acquired a small house in Lisle, Ill., that stood in the way of a developer's ambitions. The conservancy gave it to a high school teacher and Wright fan who trucked it home to Johnstown, Pa., where it sits today, awaiting reassembly.

Preservationists say the biggest challenge is making sure Wright houses are maintained well enough that demolition never becomes an attractive option. They also try to encourage owners to stay true to Wright's design.

When Mr. Thorpe the architect began working on Wright houses in the early 1970s, "Previous owners always didn't know what they had or value it," he says. Today most people not only know what they have but are willing to pay to maintain and refurbish it. "On one house I'm on my third owner," he says. "Each one has done a little more than the previous owner did."

Maintaining a Wright house can seem a full-time occupation - and cost far more than occasional trips to Home Depot.

Two years ago Linda Chambers bought a Wright house in Okemos, Mich., that had been saved from foreclosure and probable destruction. It was in bad shape. The electrical and plumbing systems were antiquated, the roof leaked, and the boiler didn't work. Ms. Chambers, an artist who works in glass, has been working on the house ever since. She asked experts beforehand to estimate the cost of repairs and modernization, but says the actual cost has turned out to be "about three times" the estimates. And she's not done yet.

Any buildings 50 or more years old are going to need attention. But Wright also experimented with new materials and methods, sometimes stretching their limits. His low-pitched roofs are famously leaky. The wide overhangs of his prairie-style houses can droop. Wright embedded hot-water pipes in concrete floors to heat his later houses. Today, these pipes rust and are impossible to replace without recourse to a jackhammer.

The reality is that few victories in historical preservation are permanent. Preservationists concede that despite the sometimes heroic efforts of homeowners and Wright fans to protect his houses, change, decay, and even loss are probably inevitable.

"There's a constant turnover," says Payne, the owner of a Wright house in New Jersey. "That is the real preservation hurdle for us. It's not like rescuing a painting by Leonardo and getting it safely into a museum and it's taken care of. As long as these houses are occupied by families in dynamic neighborhoods that are changing, even if you have a home in the best possible ownership today, there's no saying that it's going to be that way in 20 or 30 years."