This would be calculated by how much weight is above the footings.
Footing for chimneys should usually be double the width of the concrete block. For example, an 8-foot concrete block should have a 16-foot wide footing.
It most likely depends on your soil composition and the water table in your area.
There are some basic design principle that need to be applied when calculating the footing of a design in sandy soil. You should generally widen the footing for softer soil to allow more room for the bearing area. Since the cantilevered retaining wall is 4 foot then the footing should be 8 foot.
footing is footing and fooot foot foot foot
Isolated footing Transfers individual column loads directly to the soil. If a single spread footing interferes with another spread footing, the two can be combined to form a combined footing.
Combined footing
strip footing drawing and plan
It depends on what load is on the wall.
pad footing is the base of a column that transfers the load to the foundation.
That would depend on how big the addition was.
pad footing is the base of a column that transfers the load to the foundation.
Yes, a concrete patio step does in fact need to be on a footing. Without the proper footing foundation, the step will be uneven.