This idea was put forward by our first architect for consideration. The idea is to take the outline of the garage (original and new) on the east side and use this as a footprint to construct two new 'houses' to either side of the current house.
The roofs will be capped whether or not we build a second level on the garages because I'm not a fan of flat roofs. We're looking at about 9m length of wall to be built for each garage which would give us about 9sqm of space which isn't terribly efficient. It's a lot of wall compared to the space created.