Additions can add value to your home. There are different types of additions, the one where you imagine putting on some additional parts to the outside of a house creating more inner space. And the other form of additions is to convert a space in your existing home and add bedrooms or family rooms. You might have an empty basement and you can create a rec room (recreational room). This room might include a large party area with a bar and a basement washroom.
Here in Mississauga additions are quite common. Many people expand their living spaces to either accommodate more family members or just have some extra room.