Mark Sapperstein of the firm 28 Walker is already a prolific developer in Locust Point, having built office space, retail space and hundreds of housing units. Now he wants to add 120 new homes there.

The Baltimore developer said he has purchased a warehouse property directly across the street from Under Armour’s old headquarters at the Tide Point campus. Sapperstein said he plans to tear down the warehouse and build a townhome community. He declined to disclose a sales price, and the transaction is not yet publicly available in land records.

The property at 1450 Beason St., known as the “Cheer Building,” was controlled by Cross Street Partners, a Baltimore-based real estate company that had been leasing it to Under Armour. Under Armour used that building partly for office space.

The sports apparel company recently opened its new headquarters at Baltimore Peninsula, a mega-development spearheaded by Under Armour CEO Kevin Plank.

Sapperstein said he will be speaking with residents at a Locust Point community meeting next week to discuss his plans for the warehouse property. Both the warehouse and the buildings on the Tide Point campus were once part of a Procter & Gamble factory that made soap.

Right now, Sapperstein said that he envisions building 120 townhomes on a grid pattern, but that plans could depend on community feedback and road alignments. If all goes well, Sapperstein said, he would like to start the project this fall.

The new homes are expected to be three stories tall, but Sapperstein said it’s too early to know what their price point might be.

Sapperstein and 28 Walker are behind another ongoing South Baltimore residential development: Locke Landing at Baltimore Peninsula. The former factory site is being transformed into a community of townhomes and apartment buildings.

Property records show that some of the newly built homes there are selling for more than $800,000.