Fence Post Depth Code

Building codes and ordinances in your area may stipulate a legal depth and diameter for fence post holes.

Fence post depth code. If your post is 6 feet tall you will dig down at least 2 feet. The depth of your post hole plays a key role in the strength of your posts. That also means that you d need to use an 8 foot post. Gates require a hole with a depth of 36 to 40 inches in the ground and with a diameter of at least 12 inches.

Frost line by zip code. For example a 6 foot tall fence will need at least 2 feet of post in the ground. The maximum frost line depth is 100 inches as seen near the tip of minnesota north dakota and alaska all the way to zero inches in florida southern arizona and southern california. If you re setting a post into soft ground or in an area that receives high winds it s always a good idea to bury your posts a little deeper and add more concrete.

Keep the height of your fence in mind when digging your post holes. If not conventional rules of thumb offer a reliable guide. Others leave that up to the builder. For a structure it is important since any cracks caused by heaving will destroy the servicablity and appearance of the structure.

You need to dig a 12 inch wide hole for a 4 foot wood post. The code frost depth is meaningless for a fence. The depth of the post hole needs to be 1 3 to 1 2 the height of your fence. It s a lot harder to push over a post that s buried deeply so always keep that in mind.

As a general rule of thumb you ll need to place at least 1 3 the height of the post in the ground. Some cities say posts must be set in concrete. For a fence a little heaving is not easy to notice and does not destroy the servicability of the fence. Common construction requirements include post size spacing and depth.

Check your frost line by zip code or address using this map from the national weather service. For example if you are building a fence that s 6 feet tall you will need a hole that is at least 2 feet deep. For example a 6 foot tall wood fence may need 4 x 4 or larger posts spaced no more than 6 feet apart and buried in the ground at least 2 feet deep. If the map isn t accurate enough for you.