Footing sizes are related to column sizes and soil condition. The softer the ground the wider the footing should be. It is a common mistake to construct a column with footing that can weigh up to 10,000 lbs on a 3'x3' foundation in unstable ground. A small footprint will concentrate the weight with the end result of sinking or tilting. When encountering clay or soft ground it may be a good choice to install a grade beam between columns.

It has been become normal practice to for many designers and architects to specify a 3'x3'x3' footing. This will work well only in very stable stable soil conditions. We have found that most footing are better off being 18" deep with a much larger footprint. This has the effect of spreading the load and also helping prevent tilting toward the gate. Offsetting the footing so that more area is concentrated under the hanging direction of the gate can be an enhancement.

Soil with a large clay content can seem stable in the summer. During the winter the clay softens and the column will typically start tilting towards the direction of the gate in the closed position. If you are in doubt of of your soil condition you should consult with a soils engineer.