Once the wet concrete starts to set in the post hole, the window for correcting verticality closes quickly, as the notes at edmond fence installation solerarestaurant published for Edmond, OK, detail how gravity works against a fresh installation of a cedar privacy fence.
Achieving Plumb Tolerance
Standard tolerance for a vertical post is less than one degree of tilt. In Oklahoma, soil shifts can pull a post out of alignment if the concrete footing is not deep enough to reach below the frost line. To maintain this, we use a heavy grade spirit level or a plumb bob. If the post leans, you cannot simply push it back into place once the mix has reached its initial set. You must adjust the position while the slurry is still fluid. Even a slight deviation at the base becomes a significant lean at the top of a six foot picket or a heavy shadowbox section.
Mechanical Adjustment Methods
When the post is placed in the hole, we check the verticality on two adjacent faces. If the post is out of spec, use a pry bar to apply pressure to the base. For a heavy pressure treated pine rail system, the weight of the timber requires more leverage. If the tilt is toward the center of the hole, we add more wet mix to the bottom to tilt the base. If it leans away, we lift the post slightly with a jack to create a void at the bottom, then pack in more aggregate or concrete to tilt the footing itself. This mechanical shift ensures the post stays upright under the weight of the future gate hardware.
Checking the Gate Post
The gate post requires the highest level of precision. Any deviation in the vertical plane will cause the hinge to bind or the latch to misalign. We measure the plumb line from the top of the post down to the ground. If the post is not perfectly vertical, the gate will swing shut on its own or swing open unexpectedly. We often double-check the verticality after the concrete has undergone its first stage of curing to ensure no settling has occurred. A single degree of error on a gate post can ruin the operation of the entire latch mechanism.
Material Specific Considerations
Different materials behave differently during the setting process. A vinyl post is light and can be easily knocked out of plumb by wind during the pour. An aluminum or wrought iron post has more mass and requires a more robust concrete footing to resist lateral pressure. For any wood post, we ensure the base is set so that water does not pool against the grain, which helps prevent future tilting caused by rot or soil saturation.