A Southborough developer is preparing to submit an application for a 160-unit residential development in Shrewsbury under Chapter 40B, the state’s affordable housing law.

Capital Group Properties has an agreement to buy 8.5 acres of land at Route 9 and Walnut Street, which is currently occupied by a single-family home. The development would include four residential buildings, a clubhouse and parking lot.

During a June 24 meeting, Shrewsbury selectmen asked Capital Group Properties to add an unspecified amount of commercial development to the project, said Kristen Las, Shrewsbury’s principal planner and economic development coordinator. Currently, 87 percent of the town’s tax base is paid by residential properties, although the town has adopted three overlay mixed-use zones in an attempt to broaden its commercial tax base, Las said.

A formal application is expected to be submitted to the town after the developers submit a project eligibility request with MassHousing, Las said.

Capital Group Properties owns and develops offices, shopping centers and residential properties in the MetroWest and Route 495 area.