The benefits of team building have been proven time and time again. If they had not then there is no way that team building activities would still be as successful and widely used as they are. If your work is not using these forms of team building already then you should start immediately.
For many companies, the sheer number of departments they have and the nature of their work makes it impossible for members from all the different departments to interact with each other. It is hard to encourage the work-family bond when there are individuals within your company who do not even know the names of half the people in entire departments. That is why it is so important to get people from all departments to interact with each other on a regular basis.
One very effective way to accomplish this is to regularly get a couple of people from different departments to consult or work on a project together. You could easily get some HR employees in charge of immigration advertising to work with some people from the marketing department and you might get some really creative and inspired ideas for promoting a more diverse workforce. Even if you do not quite get the bonding benefit that you were hoping for you can still at least get a well-done project out of it.
If you are looking for an easy and cheap method of team building other than going on workplace retreats then revamping the work area might be the best way to go. The standard four-wall offices and cubicles are achieving the exact opposite of what you want because they are promoting isolation which can make your employees feel cut off and lonely.
Instead, you might want to choose to knock down some of those walls and go for a more open concept. By having a roomy open-floor environment with several desks or even just couches laid out, it allows your employees to feel more like they are members of a work-family.
This is a great situation for everyone because not only do your employees win but so do the people that you are helping. Maybe once a month or even just once a year you decide to make a volunteer day where everyone meets at a prearranged location and helps out a specific charity. This is helping your employees because it is getting them out of the typical office environment and interacting with each other in a more casual way. You can even go one step further and make deciding on the volunteer activity a fun team building event by having the entire office vote on which charity you help each time.