I work at an agency where this is understood. It's headphones on all day. Socialising happens at lunch and if you don't want to join in you can have your lunch early or late. Socialising also happens after work and you can go home if you don't want to join in.

Part of the reason this happens is because every task is estimated and timed. Over time the estimates have become fairly accurate so you can't get away with dossing the whole day.