Hello, My husband and I are tearing out our old plaster walls and replacing them with drywall. We know we need to insulate our exterior walls and those that face the unheated attic; what about interior walls? We'd heard somewhere that insulating interior walls can help with soundproofing.
Is this true? Are there any reasons NOT to insulate interior walls? If it *is* a good idea, what R-factor should you use?