Carl, What is the proper way to build a concrete slab foundation for a garage when you are building in an area where the ground freezes? The garage will be attached to the house if that makes any difference.
No, it makes no difference that the garage is attached to the house when considering the correct way to build the garage. The footings for the garage need to be below the frost line. Your local building inspection department can tell you how deep you need to go to get below the frost line.
After the footings are in, concrete walls are poured onto the footings to the height desired for the garage concrete slab floor. Then the floor is poured.
Image courtesy of ConcreteNetwork.com
In summary:T-shaped foundations are used in areas where the ground freezes.
First, the footing is placed.
Second, the walls are constructed and poured.
Lastly, the slab is placed.
You might want to read my article, Concrete Slab Foundation.
Carl Heldmann, byoh.com