The general rule of thumb when setting a post is that the depth of the post's hole needs to be one-third to one-half of the actual above-ground height of the post.
How Deep Should a Fence Post Be? For an average fence post, about 6 to 8 feet tall, prepare to dig a post hole about 2 feet deep. To install a fence post, you'll need a shovel or post digger, a 6-foot level, soil, and gravel or crushed stone.
As a general rule of thumb, you'll need to place at least 1/3 the height of the post in the ground. For example, a 6-foot tall fence will need at least 2 feet of post in the ground. Consider the frost line in your area.
The general rule of thumb when setting a post is that the depth of the post's hole needs to be one-third to one-half of the actual above-ground height of the post. So, a six-foot-high finished post ideally needs to be buried three feet into the ground.
In general, holes should be at least 3 feet deep for posts that extend 8 feet or more above ground level. Posts that extend 6 feet above ground level should have holes at least 2 1/2 feet deep.
The depth of the hole should be 1/3-1/2 the post height above ground (i.e., a 6-foot tall fence would require a hole depth of at least 2 feet). Add about 6 inches of QUIKRETE All-Purpose Gravel into the bottom of the hole.
1 – 4 bags of concrete per fence post are typically what's needed. This depends on the type of soil, fence design, height, post size and bag weight. In general the depth of the post's hole needs to be 1/3 to 1/2 of the above ground height of the post.
Most fence post holes will need between 1 - 4 bags of concrete to securely hold the post in place. The best way to determine the size of the hole is: Diameter of the hole is 3 times the width of the fence post. Depth of the hole is one-third to half the above ground height of the fence post.
Concrete provides a strong foundation for wooden fence posts, but can rot them more quickly. Setting them in dirt, with or without gravel or crushed rock depending on your soil type, can help the posts last longer before going rotten. You can also use metal fence post anchors to prolong their life.
The best concrete mix for fence posts I've found is Quikrete Fast Setting Concrete Mix in a 50 lb bag. It's 4000 psi, easy to work with, sets up fast, and doesn't need to be mixed. Just pour it in the hole and soak with water.
Fast-setting concrete is ideal for setting posts because there's no mixing—you simply pour the dry concrete from the bag right into the hole, then add water.
Most fence posts can be spaced 8 to 12 feet apart. While this is a general criteria, it doesn't cover all scenarios. For instance, high tensile fence can have larger spacing, requiring line posts every 15 to 20 feet for field fence styles, and as much as 20-30 feet for high tensile barbed and smooth wire.
The diameter of your post hole should be three times the diameter of your post. So, if you're planning on using a four-inch round or 4x4-inch square post, your post hole will need to be 12 inches in diameter. For a six-foot-high fence post, we would need a hole that's 36 inches deep and 12 inches in diameter.
FOOTINGS: - Poured concrete footings should be a minimum of 8” wider than the posts (4x4 post – 12” min. width, 6x6 post – 14” min. width), a two level deck or deck with roof – 24”x24”.
A 10-foot-tall six-by-six Douglas fir or southern pine post can support an area of 256 square feet under a load of 50 pounds per square foot, which is more than seven times as much as a comparable four-by-four post.
There's no question about it — the fastest and easiest way to dig post holes is to use a gas-powered earth auger. Fill the tank with gas, position the auger on the ground, fire it up, hold on tight and watch the soil come streaming out of the hole.
Therefore, the 4x4 post will likely fit into a hole drilled by a 6" diameter auger. However, this leaves less than 1/2" at the widest part for cement or dirt to be packed in to secure the post. For this reason, an 8"-10" auger would work much better and provide the necessary fill space for cement or tamping.
1 cubic yard = 27 cubic feet
In order to have enough concrete for one cubic foot, you'll require 2.2 bags of 60-lb concrete. Since bags are only sold in whole (not half, or quarter) quantities, you'll need to purchase three (3) 60-lb. bags for one cubic foot.
Fence posts should be set six to eight feet apart on a 6 foot wood fence. Do not go beyond eight feet or the fence may not be stable enough.
Calculate the post lengths
If you're setting wooden or concrete posts in concrete you'll need 8ft (2.4m) posts for a 6ft (1.828m) fence – i.e. your posts are 2ft (0.6m) longer than the fence height. Use 4in x 4in posts for fences of 5ft and over and 3in x 3in posts for anything under 5ft.
Concrete that is not moist-cured at all dries too rapidly, and reaches less than half its potential design strength. It will also have a greater number of shrinkage cracks.
With Fast-Setting Concrete there is no mixing or tools required – You simply pour the dry mix right from the bag into the hole, then add water. Fast-Setting Concrete sets in about 20 minutes so you can quickly move onto the next step of your outdoor project.