Denzel Washington is back on Broadway in “A Raisin in the Sun,” which opened at the Barrymore Theater April 3. But the project was in the works long before that.

Washington and director Kenny Leon have been planning the actor’s return to the Main Stem ever since Leon directed “Fences,” the 2010 revival for which Washington won a Tony. “Denzel said, ‘Look man, I want to come back to the stage every three or four years,’ ” Leon recalled at the opening night shindig at Tribeca Rooftop. “So we made a commitment to do it again, and we did, and hopefully in another three or four years, we’ll be back doing it again.”

Washington attributes his dedication to the stage to his early days in New York at Fordham U. “I went to see great plays on Broadway and I said, ‘That’s what I want to do,’ ” he said. “Much more than Hollywood, quote-unquote, that was the goal for me, to get to Broadway.”

So what stage gig is next for him? “Tomorrow night!” he cracked. “That’s what’s next.”

Also taking it one show at a time is LaTanya Richardson Jackson, who was a last-minute replacement for Diahann Carroll. Of all the cast members, she had the least time to prepare for her major role in a 147-page play.

“I’m having fun up there, finally!” she laughs in relief. “Because let me tell you, in the beginning, I was a loony bird.”