One of the reasons for Marc Fleisher's phenomenal success, agents say, is what he calls his symbiotic relationship with half a dozen Washington area builders.

Twenty-five percent to 30 percent of Fleisher's business is new construction, he said.

The mutually beneficial relationship often goes like this: Fleisher will be the agent selling a custom builder the land on which to build. The builder will then turn around and give him the contract to sell the houses when they're built.

And the more he works with builders, the more builders search him out, Fleisher said.

"Success breeds success," he said. "They see how successful I am with one builder [and] they call me. You have to have a track record."

But Fleisher said he has to limit his new-homes business to remain loyal to the handful of builders he works with. So, he actually turns away work.

"By ethics, I limit myself to about six builders," he said. "Otherwise you get into a competitive situation." Fleisher said that although builders may give him 10 houses to sell, they'll often want to cut a deal on the commission. He may make less on each house, but is assured several houses to sell.

Fleisher, the Washington area's No. 1 agent in dollar volume, said he works with more builders than any other Washington area real estate agent.

"He works a lot with builders," said Suzanne Goldstein, his closest competitor in terms of real estate sales. "That's one of the reasons he does so well."

Fleisher said he sells a lot of new houses because "I like the people. I like the product. New homes are some of the best value in the market." He said he does mostly upper-end infill projects: "Anything from one to 10 houses."

Builders he has worked with include Bloom Builders, Crescendo Homes, Gibson & Associates, Meridian Homes, Sandy Spring Builders and Zuckerman Brothers.

Fleisher spends a lot of his time meeting with builders. In fact, his final appointment two Mondays ago was with a builder who wanted his advice on where the driveway of a project should be, what would look better and ultimately sell for more.

"How does the driveway on the side affect the marketability?" he asked. Fleisher first suggested putting the driveway on the side so as not to mar the streetscape of the new houses. After an hour, he came around to the builder's point of view: that the driveway should go in the middle.

"Builders ask me anything from how to price their homes, what square footage is necessary for a certain neighborhood and what the layout should be to whether the garage should be in the basement or on the side of the front elevation," Fleisher said. "They even ask what appliances, what degree of crown moldings they need to get the price they want.

"I'm always meeting with builders. You don't bite the hand that feeds you."