Casting and pouring solid concrete footings. Footings form the very base of the foundation assembly; if the foundation walls are the “legs,” the footings are the “feet.”
Of course, it’s critical that footings be strong and stable. Footings can be placed on compacted backfill, but it’s better to pour them on undisturbed natural ground. Concrete is very resistant to compression but has a weakness to tension (twisting or bending), so footings in earthquake-prone regions like ours incorporate a large amount of reinforcement steel (aka “rebar”).
Footings in cold climates need to be protected from frost, which can easily exert enough pressure to break concrete. In Alaska this means burying footings deep underground or designing a “warm” foundation assembly that allows some building heat to reach the footings and elevate the temperature of the surrounding soil. Code in Anchorage requires a “warm” perimeter footing be buried at least 42 inches below the surface. Because snow is such a good insulator, it can be surprisingly beneficial to allow snow to pile up against the side of a building during cold stretches, insulating the ground and keeping the footings cozy.
Photos taken September 24, 2019. Posted November 3, 2019.