Dan Cohen AUTHOR McLean, Va.-based Elm Street Development has purchased seven adjacent parcels across the street from the former Walter Reed Army Medical Center in northwest Washington to build housing.Elm Street paid $7.0 million for the lots, representing a significant amount of appreciation due to the District of Columbia’s selection of a master developer to convert 67 acres of the medical campus into a mixed-used development calling for retail, housing, a hotel and conference center, and “innovation core.” The previous owners acquired the parcels several years earlier for only $2.1 million, reported the Washington Business Journal.“That was the main driver, Walter Reed,” said Karen McJunkin, a regional partner at Elm Street. “We like the corridor as well. But for the product we’re planning, I think that the buyer in the District is very savvy and follows what’s ahead, and will buy, we hope, based on what’s to come,” she said.Elm Street and its partner, Craftmark Homes, plan to build two-over-two style housing, sometimes referred to as stacked townhouses. The previous owners had been planning to build a 100-unit condominium. Elm Street expects to complete its first row of homes by early next year, according to the story.