Image courtesy of Boston Planning and Development Agency

Beacon Communities has closed on its acquisition of the YW Boston property in Back Bay for a planned 307-unit affordable housing conversion.

The Boston-based developer paid $51.5 million to buy the property from the YWCA of Boston Inc. The project, approved by the Boston Planning and Redevelopment Agency in April, will convert the 163,800-square-foot hotel and roominghouse into income-restricted apartments while retaining office space and the Lyric Stage Company of Boston theater.

The project adds 92 housing units for a total of 210 apartments, all of which will be reserved for households earning a maximum 60 percent of area median income.

The property includes the 66-room Hotel 140, 56 apartments, 63 single-room occupancy units, office and retail space, the Lyric Stage of Boston theater and an annex of the Snowden International School.

The plans include building renovations and new offices for the YW Boston while retaining the school, theater and offices for the residential services provider Pine Street Inn and Beacon Residential Management.