It’s what every growing family needs.

Sarah Jessica Parker and Matthew Broderick, who have three kids, quietly bought another home on Long Island’s East End — expanding their oceanfront compound to three buildings, The Post has learned.

They bought their first two homes in Amagansett for $4.6 million and $2 million. The latest, purchased in 2008, cost $5.8 million.

The couple, whose twin girls were born to a surrogate in June, may soon be spending more time in the area. Broderick is shooting an NBC pilot about an author hired to run a Hamptons newspaper.