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