How to Build a Fence Frame

I recently had to rebuild a bunch of fences on a new rental property. As you may already know, the hardest part is digging the holes and building the frame. This article explains step by step how to quickly and correctly build a fence frame.

1. Run string from one end of new fence to the other end near the ground

In order for the fence to be straight, we need to make a straight line from both ends. Since we haven’t dug holes yet, we put the string near the ground so we can mark where we want the holes for the fence posts to go.

2. Mark post hole locations

Depending on the existence of neighboring fences, we may or may not need posts at the ends. Mark where the post holes will go. Each fence panel between posts will be 8′ long. For marking the locations, you can you use a wood stake, metal stake, flag stake, or spray paint. I prefer using flag stakes.

3. Dig fence post holes

Post type

Normally people use 8′ long 4×4 pressure treated wood for fence posts. If you do that, then the horizontal 2x4s (rails) will have to be toenailed into it or secured using metal brackets.

Toenailing 2×4 rail to fence post
Fence rail bracket

Either way, that’s a lot of work, especially if you later decide to make adjustments. Also, the wood can rot and weaken over time. For these reasons, I just spend the extra money and buy steel fence posts.

The Postmaster 1-3/4 in. x 3-1/2 in. x 7-1/2 ft. Galvanized Steel Fence Post is $30 at Home Depot. These posts have holes along them for securing the rails.

Post hole diameter

The post hole diameter should be about 3 times the width of the post. Since the steel posts are 3.5″ wide, then the hole should be about 10.5″ in diameter.

Post hole depth

The post hole depth should be 1/3 to 1/2 the post height above the ground. Since we want our fence to be the standard 6′ tall, and the steel posts are 7.5′ long, we’ll make our holes 2.5′ deep.

Top of fence

The height of the fence post and the top rail above ground will be 5′. Therefore, the top one foot of the 6′ tall vertical fence boards will be above the top rail. The problem with this is that top one foot portion of the fence boards can warp.

To fix this, you can screw a horizontal piece of wood (2×3 or 2×4) at or near the top of the fence boards on the side where the fence rails are.

Soak the ground

Before digging holes. you’ll want to soak the ground, preferably overnight. This will make it much easier come time to dig. The deeper you dig, the harder the soil. One way to soak the hole locations is placing a tube for concrete where each hole would be. These tubes are 4 ‘ long so you can cut them in half.

To secure the tubes, you can dig a small hole first using a hand digger.

Or, you can just use a jack hammer with spade bit to make a circle the diameter of the tube. The tube would then be inserted into the circle.

With the tube in place, you can fill it with water and let it drain slowly directly where you want to dig holes.

Digging tool

To dig holes, the easiest and cleanest way is to use a gas-powered earth auger. You can rent one from the Home Depot ($55 for 4 hours). You can choose from a variety of auger bit diameters. Choose a 10″ or 12″ diameter auger bit.

When you are digging, if you can’t dig any deeper, then stop and pour water into the hole and let the water drain. You can then dig again.

You may run into roots and rocks while digging with the auger. In this case, you’ll need to cut the roots using a reciprocating saw or break up the rocks using a jack hammer.

4. Insert posts and secure rails

Now that you have 2.5′ deep holes, you can insert the steel posts in them and screw 3 horizontal pressure-treated 2×4 rails between the posts.

Picture showing 3 rails between posts

Since each hole diameter is about 10″ or 12″ in diameter, and each post is 3.5″ wide, you have room to move each post so that a standard 8′ long 2×4 will fit between each post. Screwing the 2x4s in place before pouring concrete helps ensure the posts are plumb.

5. Plumb and brace the posts

To ensure the fence is straight from one end to the other, tie a string at both the top and bottom of both end posts. Then adjust the position of each post in between and using a fence post level, check for plumb.

To hole the posts in place, brace them using stakes. I prefer hitting a 2′ long steel stake straight into the ground and then screwing piece of wood horizontally between the steel stake and the post. The steel stakes are pre-drilled. There should be two braces perpendicular to each other to hold the post plumb.

6. Pour concrete

Mixing concrete is a hassle and a mess. Instead of doing that, just use Quikrete 50 lb. Fast-Setting Concrete Mix which doesn’t require mixing.

Pour the dry concrete mix in the hole up to 3-4 inches below the ground. Then pour 1 gallon of water for every 50 lb of concrete mix. The mix will set hard in 20 to 40 minutes. If you are unsure if the concrete will completely mix with the water, you can divide the concrete and water in half and or a third and work progressively.

Wait about 4 hours continuing work on your fence.