What kind of concrete should I use for fence posts?

Asked By: Greta Fortea | Last Updated: 7th March, 2020
Category: home and garden home appliances
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Fast-setting concrete is ideal for installing fence posts since it doesn't need to be mixed in a bucket or a wheelbarrow. Once you've finished digging your post holes, add about three to four inches of gravel into the bottom and compact it using a post or a 2x4.

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Also know, should fence posts be set in concrete?

Setting Fence Posts in Concrete Concrete is the most secure material for setting fence posts, especially if you have sandy soil. Gravel may be okay with dense, clay-heavy soil, but in looser soil, concrete is the only thing that will truly keep your fence posts stuck in place.

Also Know, is 2 feet deep enough for fence posts? The minimum depth that you should dig your fence post holes for panel sections is 2 feet. A general formula is to dig the holes one-third to one-half of the post's aboveground height. The deeper you dig the holes, the more stability your fence has, but you must also purchase longer posts.

Likewise, how much concrete do I need for fence posts?

Also 1-1/2 bags per hole is about right for a 4x4 fence post. Also remember, the depth of the post hole should be one-half of the above-ground post height. (Example: For a 6' above ground post, use a post with an overall height of 9 feet and place 3 feet in the ground).

How do you keep fence posts from rotting in concrete?

Caulk around the fence post base Apply high-quality exterior acrylic caulk, or silicone specifically designed to adhere to concrete, at the base of the post. If your cedar wooden fence posts are rotting at the bottom, you need to replace them. The rot probably developed because the posts were installed improperly.

25 Related Question Answers Found

How do I keep my fence post from rotting?

  1. Set the wooden fence posts in a cool, dry area with plenty of air circulation so the wood can dry.
  2. Brush the bottom third or bottom half of the fence post with waterborne copper naphthenate, a wood preservative that is free of arsenic and chromium.

How do you reinforce a fence post?

Method. To begin reinforcing the post, dig a few inches of soil away from it around the perimeter. Fill the hole with approximately 6 inches of gravel. Top the gravel with rapid-set cement mix powder to fill the hole to 3 inches below the surface of the soil.

Will wooden posts rot in concrete?

A: Actually, your point is well taken. Simply setting the posts in concrete does create a condition that will accelerate rot in the bottom of the posts. With pressure-treated posts, the rot will be slow. Concrete should be poured around the post - no concrete under the post.

How much of a gate post should be in the ground?


The more concrete, the better. Rule of thumb is that 1/3 of the post should be in the ground. A 6' fence should be sunk into the ground 3', so you'd need 9' posts. As Shirlock states, even that won't likely support an 8' wide gate.

How do you backfill a fence post?

Use a mix of crushed gravel and soil to backfill the hole around your new post - compacting the soil every 4-6 inches as you go.

  1. Dig your hole to a depth appropriate for the height of the post.
  2. Place a pre-cast concrete biscuit (block).
  3. Place your post in the hole and backfill with dirt.

How big of a hole do I need for a 4x4 post?

Dig an 8"-diameter hole at least 6" deeper than your area's frost line for each 4x4 post, using a power auger, hand auger, or post-hole digger. A 6x6 post requires a 10"-diameter hole. Shovel a 6" layer of gravel into the hole to provide drainage.

How do I calculate how many fence posts I need?

Calculate the number of posts you need. This depends on the post spacing, which in most cases is 8 feet. Divide each section by the post spacing to get the number of posts in that section, then add the posts in all sections. A 200-foot fence with equal sides needs six posts spaced by 8 feet per side, for a total of 24.

Can you build a fence without sinking posts?

If you need a temporary fence or a border that you can move as needed, a quick way is to use concrete blocks. Attach a bracket to a concrete block that is heavy enough to hold the wood or other material you plan to use to build the fence. The posts can be mounted to the brackets and the fence finished from there.

Should you put gravel under fence post?


Gravel also allows water drainage around the fence posts, making the posts less susceptible to frost heaves. Dig the holes the same way as you would to set posts in concrete. When setting fence posts in gravel, you should bury at least one-third of the fence post. Use crushed gravel to set the posts.

How long does it take for concrete to dry for fence posts?

Typically, you can apply some weight to the posts after 4 hours, but it's a good idea to wait at least 24 hours before resuming fence construction. Standard concrete mixes may take up to two hours to set and should cure for 24 to 48 hours before any forces are applied to the posts.

How deep should a 16 foot post be in the ground?

In general, holes should be at least 3 feet deep for posts that extend 8 feet or more above ground level. Posts that extend 6 feet above ground level should have holes at least 2 1/2 feet deep.

How long do pressure treated fence posts last?

Most treatment companies claim that when treated, most lumber will last more than 20 years. This holds true for pine and spruce, while cedar may last up to 40 years.

How deep should steel fence posts be set?

The standard rule of thumb is to bury at least a third of the length of the fence post in the ground (half is better), but local building codes may require a minimum depth, such as 30 inches, so check with your local building authority before you start.

How long should a fence post be?


The normal in ground length is 2 ft, so you buy 8 ft posts for a 6 ft fence. The normal wood fence has the boards on only one side of the posts so in your case you will have to decide who gets the more finished side and who has to view the posts, or you could put boards on both sides.

What size fence post do I need for a 4ft fence?

Hole Sizes for Fence Posts and Posts
Post size Height of post above ground Hole size (width x depth)
1.2m (4′) 23cm (9”) x 40cm (18”)
1.8m (6′) 23cm (9”) x 60cm (24”)
100mm (4”) 90cm (3′) 30cm (12”) x 30cm (12”)
1.2m (4′) 30cm (12”) x 45cm (18”)

What size fence post do I need for a 6ft fence?

If you're setting wooden or concrete posts in concrete you'll need 8ft (2.4m) posts for a 6ft (1.828m) fence – i.e. your posts are 2ft (0.6m) longer than the fence height. Use 4in x 4in posts for fences of 5ft and over and 3in x 3in posts for anything under 5ft.