Fence Installation: Advice for Posthole Placement and Alignment, Depth, and Tools

The initial step of fence installation, digging the holes for the fence posts, may seem simple, but it’s extremely important as it serves as the foundation of your entire fence. In order to prevent a collapsed fence installation it’s important to keep the following in mind:

Posthole Placement and Alignment

Linear alignment is one of the most important components of posthole placement. For a fence installation with posts that are all the same size, you can place a post at each corner, and then incorporate additional posts 8-10 feet on center. To mark the locations of the posts, you can use stakes and tie a line to each corner stake.

If you are using posts that are different sizes, you will first need to find the location of the first corner post and draw a circle on the ground with the same diameter as the post. Then go to the opposite horizontal or vertical corner of the fence and repeat that process. Then stretch a line between the outer edges of the two corner posts and repeat with the remaining corner posts. Starting with the smallest post, mark the positions of the posts in order of size. Remember that as the sizes of the posts increase, you will need to counterbalance the marks so the outer edges of the posts line up evenly with each other.

If your corner posts are a different size than the in-line t-posts on your fence installation use a different color paint to mark each post’s location on the ground. This will come in handy when you need to remember to use a different-sized posthole digger for each posthole.

Posthole Depth

Depending on where you live, the depth at which you dig your postholes can change. 48 inches, (4 feet) below the frost line is an ideal depth and if you don’t go below that line, freezing weather may cause structural damage to your fence in the long term. Ask a neighbor or city planner if you are unsure about where your frost line is.

If you live in an area that doesn’t freeze, all you have to do is dig the posthole 4 feet deep. Use a spirit level to make sure the bottoms of the postholes are level so your fence installation will be plumb and aligned correctly.

Tools for Digging Postholes

A posthole digger and an auger are the two main tools for digging postholes. The posthole digger is a manual tool that resembles two small opposing shovels that are connected by a fulcrum. Separate the shovels by spreading the handles and then place the digger in the ground and close the handles together to make the tool grab some dirt. Then remove the digger from the ground, empty the contents, and repeat. This tool is ideal for smaller postholes that don’t need to be too deep.

The auger is better for bigger posthole projects. This tool is like a big drill and comes in a variety of sizes. If neither of these tools appeals to you, you can always get in contact with a cedar fencing contractor and have them take care of the measuring, spacing, posthole digging and heavy lifting for you.

Aside from the postholes, the most important component of a fence installation is safety! Your safety and the safety of your family and neighbors is what you should focus on before starting the installation process. Before your digging project, call a local utility company to find out if there are any underground gas, water, or electric lines along your fence line.