# How to set a fence post in concrete?

Fence post work is governed by mix, exposure, and local requirements. Typical thickness is a hole one-third of the post height and three times the post width and typical strength is 3,000 psi (21 MPa), or a fast-setting post mix. Every figure on this page carries the source it came from, and jurisdiction-specific requirements are set by your local building department.

## Short version

## Does the answer change by state?

People search this question with a state attached — concrete for fence, concrete among them — and the underlying material behaves the same everywhere. What changes is exposure and jurisdiction: freeze-thaw cycles decide whether air entrainment is required, deicing salt raises the exposure class, and frost depth, permits and the adopted code edition are all set locally.

Requirements are set by your local building department, not by any national table. See the state pages for cost bands, exposure classes and the authority that governs your address.

## Common mistakes

- **Skipping the cure** — concrete hardens by hydration, and drying it out early costs strength permanently
- **Ignoring exposure class** — freeze-thaw and deicing salt require air entrainment under ACI 318
- **Treating a jurisdiction-specific requirement as universal** — frost depth, permits and code editions are set locally