For a fence a little heaving is not easy to notice and does not destroy the servicability of the fence.
Fence post depth code.
If the map isn t accurate enough for you.
Check your frost line by zip code or address using this map from the national weather service.
Here are a four tips to help you find the correct fence post hole depth.
If not conventional rules of thumb offer a reliable guide.
For example a 6 foot tall fence will need at least 2 feet of post in the ground.
If your post is 6 feet tall you will dig down at least 2 feet.
Others leave that up to the builder.
That also means that you d need to use an 8 foot post.
You need to dig a 12 inch wide hole for a 4 foot wood post.
As a general rule of thumb you ll need to place at least 1 3 the height of the post in the ground.
For the width you need to make the hole three times the width of the post you intend to use.
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.
Frost line by zip code.
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.
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.
For a structure it is important since any cracks caused by heaving will destroy the servicablity and appearance of the structure.
Gates require a hole with a depth of 36 to 40 inches in the ground and with a diameter of at least 12 inches.
It s a lot harder to push over a post that s buried deeply so always keep that in mind.
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.
The depth of the post hole needs to be 1 3 to 1 2 the height of your fence.
That is why there is a specified depth for building footings.
Keep the height of your fence in mind when digging your post holes.
The code frost depth is meaningless for a fence.
The depth of your post hole plays a key role in the strength of your posts.