Installing Fence Posts in Concrete

Before Installation

Some localities require a permit to put up a fence, so check with your local building code office first. You also need to know where the boundaries of your yard are. If there are any underground utilities in the yard, mark their locations so you don't dig into them. The utility company will come out to the property and mark the area with a bright-colored spray paint.

Chain-Link Fence Posts

When installing a chain-link fence, there are two types of posts. The corner, end and gate posts are called terminal posts. The posts between them are called line posts. Because the terminal posts have to take the pressure and pull of the fencing fabric, they are set slightly different than the line posts. Once the locations for the posts have been marked, dig the holes for the terminal posts. The holes should be 8 inches around and about 30 inches deep. They should be wider at the bottom of the hole than at the top. This serves as an anchor in the dirt. Mark the poles with a crayon to show ground level. The measurement for the mark is the height of the fencing fabric plus 2 inches. The posts are then centered into the hole with the crayon mark being at ground level and the posts checked for plumb. Concrete is then poured into the hole to over the ground just slightly. The concrete is then finished with a trowel to slope down to keep water away from the post. The posts, once installed, should be checked for plumb and level again. Once the concrete starts to set, it is too late to adjust the posts.

The line posts are done in the same fashion, except the holes are 6 inches wide and 18 to 24 inches deep. By setting a string on the terminal posts at the 4-foot level, the height and level of the line posts can easily be determined.

Vinyl and Wood Fence Posts

Vinyl and wood fence posts are set using sloped holes approximately 10 inches in diameter, with the bottom being larger than the top. The depth of the terminal posts should be equal to about one-third of the post. Line posts do not have to be set quite so deep; they can be as much as 6 inches higher. The holes should be dug 6 inches deeper than the length of pole that is being buried for the purpose of filling with 6 inches of gravel. The gravel will keep water draining away from the post. Once the holes are dug and the gravel is placed in the hole, it can be filled with concrete. For a vinyl fence, quick-setting concrete can be used. The posts should be tapped into place slowly so the concrete can fill the inside as it moves down all the way to the gravel.

Wood fence posts should go into the hole first and then the concrete. The plumb and level should be checked with each post before the concrete starts to set. A string can be hung between the terminal posts to make sure the line posts are correctly put in line. Once the concrete starts setting on each post, it can be topped off and sloped away from the post to keep water draining away. Wood posts should be made using treated lumber, or the sections that goes underground can be soaked in a preservative overnight before they are installed.