Buyers wait anxiously for months to move into new homes that in theory were built to their specifications. Isn't that the reason most people build, to get it just the way they want it so they can sit back and enjoy it?

Not necessarily. Many of them begin immediately to change their houses, spending thousands of dollars. Just about as many new buyers are already thinking about what they want in their next house, which they hope to buy within a few years.

A survey by Builder magazine and the Joint Center for Housing Studies at Harvard University found that although most home buyers say they're satisfied with the overall product and experience, the industry could do more for them. The national survey last year questioned people who bought homes in the previous two years and people who had remodeled extensively.

"One of our major findings is that customer service leaves a lot to be desired," said Builder editor Boyce Thompson. He said that although the researchers knew that customer satisfaction after construction long has been a problem for builders, they were surprised at some of the numbers.

For example, among those who had their homes built, about 33 percent of first-time buyers and about 25 percent of repeat buyers said they were unhappy with the level of service they received after construction, the "callbacks" to fix imperfections, large or small, that often appear in new homes.

"Builders ought to know that one-third of their customers are saying bad things about them at dinner parties," Thompson said. "This is not a good number in any industry."

On the other hand, only about 10 percent of the buyers expressed overall dissatisfaction when asked to factor in their impressions of service in such categories as purchasing and contracting, construction, financing and the general quality of homes.

Tom Stephani, who owns William Thomas Homes in Crystal Lake, Ill., and conducts seminars for builders on customer service, said he was not surprised at the dissatisfaction over callbacks.

"It rings completely true," Stephani said. "The callbacks, even if they are tiny, they aggravate things. They really drive a wedge between the buyer and the builder."

Recent buyers told the researchers that when they set out to buy homes, about 30 percent of them started with a preference for new construction and 30 percent preferred an existing house.

"There's a big group in the middle that could go either way, and it's in the builders' interest to scrutinize how that middle was swayed," said Sal Alfano, editor of Builder's sister publication, Remodeling, a trade journal that also participated in the research.

The study concluded that, at the most simplistic level, the big attraction of "new" is the promise of minimal maintenance, and the decision to buy existing houses is based on location.

The largest group of new-home buyers, 27 percent, said maintenance was the main factor in their decisions. Other reasons, in descending order, were that they thought a new home would be less expensive, the design would be exactly what they wanted and that they didn't want a fixer-upper. Only 12 percent of the buyers said they chose to buy new homes because their quality would be better than that of resale homes.

And the location question for many resale buyers apparently translates into a desire for a "mature" neighborhood, according to the researchers. Much of that maturity comes from trees and landscaping, they said.

Kermit Baker, director of the Harvard housing group, said that a surprising finding was how much money buyers of new homes spend on changing them within two years of purchase, and that much of it was spent on landscaping.

"The average first-time buyer of a new home is spending $3,500 in two years," Baker said. About 41 percent spend $5,000 or more. About 56 percent of repeat buyers of new homes spend more than $5,000 in the first two years.

"About $4 billion to $5 billion per year is spent by buyers of new homes on home improvements," Baker said.

A lot of buyers, 84 percent, put money into landscaping, according to the study. About 65 percent of the new buyers installed decks or patios.

Other frequent switches involved replacing the brand-new light fixtures (59 percent), changing the flooring in one or more rooms (41 percent) and replacing window treatments (53 percent). Eighty percent said they repainted at least one room within two years of moving into their new homes.

Thompson said the survey findings about landscaping reflect a couple of things that competitive builders ought to consider. If, as the study suggests, a driving consideration for resale-home buyers is their desire for mature landscaping, then builders ought to offer more elaborate landscaping to lure the resale buyer who might go either way.

Stephani said some projects would do well to offer larger trees, but sometimes it just isn't an economic option when the overall goal is just livable housing. People "fight to be able to afford the square footage, and they fill up their budgets with all the basics," he said. "The one thing that they can put off and do on their own is landscaping."

Stephani isn't surprised that buyers of new homes turn around and spend large sums on "dream homes."

"Absolutely, there is a ton of stuff to do, unless you are willing to pay the builder an unbelievable amount. It's a matter of paying all the different tradespeople to do specialized interiors and other stuff. Yes, people may be a little bit surprised that there is so much to do to make it a new home."

Another major conclusion of the study is that buyers of new homes and old seem to be constantly thinking about what they're going to buy next. That is a reflection less of dissatisfaction than of real estate wanderlust, Thompson said.

"Buyers are restless and want more space," he said.

"Nobody is happy with what they have," Alfano said. "What they're looking for is more space. They're looking for something better."

According to the survey, 11 percent of first-time buyers of new homes and 25 percent of those repeat buyers considered their purchases to be a "dream house" where they would live for the rest of their lives.

Across all categories of buyers of new and existing homes, one-third to one-half of them said they were happy with their residences "for now," but intend to move relatively soon. Among first-time buyers of both kinds of housing, about one-third expect to move within three years. Almost another third, in all categories, think they will be gone in five years.

And, even though the study was conducted last summer, at the height of media speculation about investors fleeing the stock market and diving into real estate, fewer than 8 percent of the buyers said they viewed their homes primarily as investments.

"I think everybody feels they want to be on this housing escalator," Stephani said. "When equity and their incomes increase, they can jump to the next one. We are in such a mobile society. Nobody feels like they are going to stay in their homes the rest of their lives."