Footings are the roughly one-foot thick slabs of concrete on which the foundation walls of the house rest. They are designed to be large enough to distribute the weight of the house onto the excavated soil surface such that the soil does not collapse from the load. As a practical matter they tend to be 20-72 inches wide depending on what part of the house they support. They usually need to be 24-48 inches below the ground surface (depending on region) to be below the frost line.
Placing the footings is a pretty remarkable thing to watch. A crew of 8 (Stone Construction) arrived at 7am and they left around 6pm. With another two hours of work the next morning to strip the forms and pack up, I had completed footings.
This not a fussy construction task. They take a trailer full of lumber and hammer it together in the rough shape they’re after. They pump the forms full of concrete, and then trowel the top surface to a snapped line, which defines the top surface of the footing. The foundation walls are then built on top of these troweled surfaces. The photos tell the story.