Brandon Henry, Greystar managing director, expects the deal to build at the site to close before year-end. (Jeffrey MacMillan/Capital Business)

Hopes for high-rise housing development in Tysons Corner — a key part of Fairfax County’s plan for the area — got a boost recently when the developer behind the county’s demonstration project reached a tentative deal with a home builder to construct a 25-story, 404-unit apartment building near one of the planned Silver Line stations.

The Georgelas Group, selected to be Fairfax County’s partner on a 28-acre demonstration project near the coming Tysons West Metrorail station, plans to name Greystar, the nation’s largest manager of apartment units, to build the project’s first apartment tower. The tower would be a striking change to the Tysons landscape.

To be built, both the apartment project and the rest of the Georgelas proposal require zoning approval from Fairfax County, which has not yet considered the plans.

In the deal, Georgelas would sell land at the intersection of Leesburg Pike and Spring Hill Road to Greystar, a South Carolina firm with offices in Tysons, and Greystar would build the tower. Both a developer and manager of apartments, Greystar manages more than 187,000 units, considered tops in the country. The Tysons development would be its third in the area, after others in Woodbridge and St. Mary’s County.

Brandon B. Henry, a managing director at Greystar, said the company had been looking at sites in Tysons since opening an office there in 2008. He said he expected the Georgelas deal to close near the end of the year, but he did not disclose the purchase price.

“The fact that you can hear it and you do see it, it’s real. It’s not like the Metro’s coming, the Metro’s not,” he said. “The Metro is coming and it’s going to be a big deal.”

Henry said the Georgelas plan offered advantages because it was likely to be the neighborhood’s first high-rise housing development.

“I’ve looked at other sites around Tysons and I think what drew me to the area was not just the fact that Georgelas was going to be the first to go to rezoning, but [also] you’re in front of the wave of supply,” he said.

Aaron Georgelas, Georgelas Group partner, said Greystar had “been a great partner in working through this process.” He and Henry both cautioned that the plans were contingent on zoning and other approvals from the county.

A 25-story apartment tower beside an Exxon station, a McDonald’s and much shorter office buildings would be a dramatic addition to Tysons, and it would begin to bring the density to the area that planners and members of the county council had been seeking.

“In concept, let me just say that this is consistent with what we are hoping to see in Tysons and with what the new plan called for . . . more residential and especially more residential close to and within walking distance of the stations,” said Fairfax County Board Chairman Sharon Bulova (D).

Bulova added that she was particularly pleased that Georgelas and Greystar were prepared to meet the county’s requirement that 20 percent of the units be “workforce units,” meaning offered below market rate to those who cannot afford top rents.

Henry said a mixed-income building was part of Greystar’s vision. “We are going to appeal to the entire cross section of Tysons and I am excited about that,” he said.

Despite the strengths of the Washington-area apartment market, there are still doubts about whether builders of high-rise towers in Tysons will be able to successfully charge enough in rent to offset the larger construction costs of taller buildings. But Henry said the success of Reston Town Center showed that people in Fairfax County wanted more options for urban living.

“At the end of the day it’s a choice of where people want to live, and Reston’s a good example of that,” he said. “If you want to live in a garden apartment in Tysons, you can do that too.”