Two weeks ago, board member Andres Perez held a teach-in on how to wrest “control” of vacant apartments. He called it “homesteading.”

“The best time to enter a building is in the late hours,” he advised a group of about 20, who gathered in front of the half-empty East New York housing complex Arlington Village.

“You make sure you have your proper tools. You remove the chains and padlock, and then you go in.”

He then led them through the next steps — including filling out a change-of-address form at the post office and setting up utilities. After that, “nine out of 10 times the courts will allow you to be able to have control of the property,” he said.