Unlike a standard cripple wall which uses platform framing, balloon framing does not have a top plate to which the plywood can be nailed. In our video on cripple wall retrofits we talk a lot about top plates. Split level homes such as the one shown above, which were common in the thirties and forties, also often have balloon framing because the main lower floor is nailed to the side of the garage wall. In other words, first they built the garage with the room above it and then nailed the floor of the main house to the side of it. We also find it in many homes built before 1920.
These split level homes actually require two retrofits, one is to attach the main floor where the living room and kitchen are to its foundation. The other is to attach the living area above the garage to its separate foundation. The lower floor is relatively cheap. The upper floor, called a soft story, is quite expensive.
Balloon framing comes in many configurations and requires very specialized retrofit techniques that cannot be found in any of the available retrofit guidelines. Below are some images that show the difference between common cripple wall framing and balloon framing. Notice how the image on the right does not have a top plate.