How Deep to Dig Fence Post Holes

Fences are fantastic for fixing up a boring yard, creating a private space from peering neighbors or keeping animals in – or out – of your favorite spaces. A good fence can last for decades, and building a sturdy, durable fence starts at the foundation. Erecting a solid fence is a fairly fast project once the foundation is firmly in place.

Wooden fence on green garden
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How Deep to Dig Fence Post Holes

What Makes a Good Hole

Digging a hole seems like the easiest part of the process. Even a kid can get a good-sized hole going in a small amount of time. But the hole is a pretty important part. Too big, and you can jeopardize the structure's ability to hold up to strong winds. A hole that is too small is simply an annoyance as you have to drag everything out and start digging all over again. The post holes you dig for your fence need to be evenly spaced from top to bottom. When you begin to dig a hole, they tend to be larger on top where the shovel uses the ground for leverage to scoop out the earth.

Foundation Issues

Since we tend to build with a bigger top than bottom, we create v-shaped holes. V-shaped holes just won't do if you fill the hole with concrete. Frost will heave the concrete toward the sky, making room for soil and water to rest beneath the footing and causing your fence to lean and eventually fall over. Dig the holes but only fill them up halfway with concrete. This will keep them from the hands of frost pulling them up and getting a good grip on the lip of v-shaped concrete blocks.

Depth Considerations

A beautiful fence starts with a well-made hole. To dig a good post hole, you need to go down a third and up to half of the height of the post height above ground. If your post is 6-feet tall, you will dig down at least 2 feet. For the width, you need to make the hole three times the width of the post you intend to use. You need to dig a 12-inch wide hole for a 4-foot wood post. Gates require a hole with a depth of 36 to 40 inches in the ground and with a diameter of at least 12 inches.

Safety and Tips

Before you go around digging on your property, give a buzz to the 811 call center in your state to ensure you won't be knocking out any power, shoveling into sewage or water lines or taking down cable before the big game. Always wear safety goggles when digging as well as a long-sleeved shirt, pants and gloves because digging brings up a lot of loose objects that can be sharp and go flying when hit from above.