State and city officials are cheering a financing milestone in the redevelopment of the Mary Ellen McCormack public housing complex in South Boston, a project that features the replacement of all 1,016 public housing units currently on site and the addition of more than 2,200 new, mixed-income rental homes.

The Boston Housing Authority and developer WinnCompanies announced Thursday they have secured financing for the first piece of the project, a new 112,000-square-foot building with 94 modern apartments for low-income families currently living at the Mary Ellen McCormack. All systems in Building A will be electric and it will feature a geothermal system with ground source pumps for heating and cooling.

The $62 million building will have 37 one-bedroom units, 44 two-bedroom units, 12 three-bedroom units and one four-bedroom unit, Winn said. A task force of tenants was involved in design decisions, the developer said, and all current residents at the McCormack have a right to return to new apartments once complete.

"This undertaking at Mary Ellen McCormack represents an important investment in affordable housing and, equally important, an investment in our residents and our families," South Boston Rep. David Biele said. "I am grateful for the partnership and collaboration between Boston Housing Authority residents, WinnCompanies, elected officials and government agencies to preserve and enhance affordable housing in the South Boston community while addressing needs in the neighborhood and around Mary Ellen McCormack as identified by residents."

The work on Building A, expected to be complete in the fall of 2026, will run alongside $8 million in infrastructure improvements, BHA and Winn said. That includes a new Veterans Park with an accessible "tot lot" and splash pad, a two-way separated bike lane, reconfigured public streets and intersections, pedestrian enhancements, new trees and planting areas, and pedestrian zones.

The complete redevelopment of the McCormack, which opened in 1938 and is one of the largest public housing developments in New England, will feature eight new residential buildings to comprise a 3,300-unit mixed-income and mixed-use community, more than 70,000 square feet of retail, a new park, freshened street-level infrastructure and a new community center. The full project is expected to take shape over the next two decades, though the residential portions are expected to be complete in about a decade, Winn said.

At a time when the state wants to encourage housing production, especially of affordable homes, Thursday's announcement that BHA and Winn secured financing for the first part of the McCormack project detailed just how many moving pieces must come together to make a project of that scale possible.

"Funding for the construction of Building A is being provided in the form of a construction loan from the Bank of America; federal Low Income Housing Tax Credit and Energy Tax Credit equity from Bank of America, a tax-exempt bridge loan and tax-exempt first mortgage loan from MassHousing; a subordinate loan from the Affordable Housing Trust Fund maintained by the Massachusetts Executive Office of Housing & Livable Communities; a subordinate loan from the BHA; and state Low Income Housing Tax Credit equity from Bank of America with a loan from BlueHub Capital," the release said.