Dig the footer trench 24 inches wide and 16 inches deep. Remove the soil by loosening it with a pick ax and shoveling it out with a shovel. Measure the width and depth of the footer trench regularly to ensure that it is consistent. Lay a 4-foot level along the bottom of the footer trench to level the soil.
Install horizontal rebar in the bottom of the footer trench. Place two runs of rebar along the footer trench on rebar chairs. Cut 24-inch rebar and place them across the horizontal rebar 24 inches apart along the trench. Tie the cross bars to the horizontal rebar using tie wire.
Cut rebar into 24-inch lengths. Drive the rebar vertically into the footer bottom using a hammer. Begin at one corner, driving the first rebar down so that it extends 12 inches from the bottom of the footer trench. Place the next rebar 24 inches away and along the footer, and drive it down until it is level with the previous rebar. Use the 4-foot hand level to reference each piece with the previous one. These rebars are reference points for concrete heights in the footer trench.
Pour concrete to the top of the vertical rebars, using a hard rake to spread the cement around in the footer trench. Pack the concrete with the hard rake, locating the tops of the rebar pins with the rake teeth. Complete the footer by smoothing the concrete with a concrete trowel, allowing the concrete to dry for 48 hours before placing weight on the surface.