Measure and Set the First Post
Watch video of this step.
To begin the fence, measure the area where you’d like to build it. Our fence will be 48 feet long. Place stakes in the ground at about a foot or two beyond where you want the end posts (image 1 below).
Connect a taut string as a guide for the path of the fence. Near one end of the guide string, make a mark for the first outside post. The first post is placed where you want the fence to begin.
As a rule, set fence posts about 6 to 8 feet apart. A fence that is 48-feet long will have six to eight posts.
Use a post-hole digger to make a hole 8 inches wide and just over 2-feet deep (image 2).
Pour about 4 inches of gravel for the base, and then insert the 8-foot 4x4 post into the hole. Then pour dry concrete into the hole surrounding the post. Use a three-way level to make sure the post is standing straight. Tamp down the dry concrete (image 3).
In moderate climates, many contractors use this dry concrete technique, which draws natural moisture from the ground to harden or "set" the packed concrete around the post.
Another option is fast drying concrete mix. Once placed in the holes, it will take up to 48 to 72 hours to dry.