River Valley Remodelings Blog
Currently any detached structure under 600 square feet does NOT need footings, or a foundation 42" below grade for frost protection. A two car garage typically measures 24 feet X 24 feet which is 576 square feet. To me putting up a building of that size in New England without a proper foundation on footings below frost line is foolish.
I have seen concrete move up and down as much as 6 inches in prolonged cold snaps in Connecticut. This much movement can damage a garage, crack the slab, and open the door to future problems.
If I build a garage, I expect to be there 100 years from now. Current codes call for all kinds of harware so your garage or building cant be destroyed by up lift ( winds trying to lift the building from its foundation). So why not protect it from heaving?