I believe the need, or not, for footers is climate/soil dependent. With good soil (solid, well drained) you'd likely be fine w/out any footers if the garage is detached. I believe the shallow footers (thicker slab at edges) are for structural strength, not frost reasons. Just keep them "warm" or dry as a bone if you do get frost. I built a 14x44 addition onto my house 25 years ago, SOG, no footers. It is attached to the upper floor of my daylight basement house and it has not moved one iota... yet. However, the ground is pretty solid and the grade drops off noticeably so the water runs away from the house. AKdiesel: I think it is funny that you said "permafrost"! We need to remember that some lucky folks live where they have a moving frost line instead of permafrost. I sometimes mention to people about how easy it is to push over medium sized trees, forgetting that they have tap roots; way tougher than our trees.