Post Hole Concrete Calculator

Post Holes Below the Frost Line

In Grayson County, the frost depth is approximately 12–18 inches. Any post that supports a structure — deck, fence, carport — must be set below frost depth to prevent heaving. UIR sets all structural posts to a minimum of 24–36 inches depending on the structure, providing a safety margin above the local frost depth requirement.

Concrete Mixing Options

For post holes, two products work well: standard ready-mix concrete (mix with water and pour) and fast-setting concrete (pour dry into the hole, add water, done in 20–40 minutes). Fast-setting products like Quikrete Fast-Setting Concrete are ideal for fence posts and light structures where you don't want to brace posts while the concrete sets overnight. For load-bearing deck posts and structural applications, UIR uses standard 3,000–4,000 PSI concrete mixed to the correct water-to-cement ratio for maximum strength.

Setting Posts Correctly

The post bottom should be cut flat. Place 3–4 inches of gravel at the bottom of the hole for drainage before setting the post. Brace the post plumb in two directions before pouring concrete. The concrete crown should slope away from the post at grade to prevent water pooling — a leading cause of post rot at the base. For deck posts, UIR uses post bases anchored to concrete piers rather than direct burial, which dramatically extends post life by keeping the wood above grade.

Contact UIR for any post-set or structural work in Grayson County.