How to Set Posts in Concrete

Posts set in concrete provide sturdy support.
Posts set in concrete provide sturdy support. (Image: Jupiterimages/ Images)

With installations such as porches, decks and fences, the structure itself is only as stable as the posts holding it up. For this reason, many builders set the support posts in the ground, with concrete poured in around them. This provides a stable footing that withstands weathering, wind and the weight of the construction. Quick-setting concrete gives you a moderately easy way to get quality results.

Things You'll Need

  • Shovel
  • Hand tamper
  • Gravel
  • Level
  • Braces
  • Concrete mix
  • 5-gallon bucket or wheelbarrow
  • Hoe (optional)

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Measure the portion of each post that will be above ground. Divide the measurement by 3 and add 6 inches. Dig a hole that is this deep and is three times the diameter of the post. For example, if you have a 6-inch-diameter post that will sit 6 feet above the ground, the hole will be 18 inches wide and 2 feet, 6 inches deep.

Dig the bottom of each posthole about 1/2 to 3/4 inches wider than the top; this will provide a more adequate base and prevent the posts from sinking in. Tamp the bottom and sides of the holes with the hand tamper to make them completely flat.

Fill the bottom 6 inches of each hole with gravel to help water to drain away and prevent your posts from rotting or rusting. Tamp down the gravel to make surface flat.

Set each post on top of the gravel in the hole. Place a level along the post to check that it's standing completely straight. Adjust the post if necessary. Attach braces to each post and the surrounding soil to hold it firmly upright.

Mix quick-setting concrete and water in a 5-gallon bucket or wheelbarrow, according to ratios specified in the product's directions. Stir the ingredients with your shovel until you achieve the proper consistency.

Pour the concrete into each posthole until it fills all but the top 1/2 inch.

Slope the concrete surface gently away from each post, using a shovel or a hoe, to allow water to run off. Pooled water can cause rust or rot.

Set the level against two sides of each post to check that it is completely plumb (vertical). Adjust the braces as necessary so that they hold the post completely upright as the concrete dries. Allow the concrete to dry for a full 24 hours before removing the braces or adding any weight to the posts.

Tips & Warnings

  • If you purchase a post kit from a hardware store or home-improvement retailer, it should come with braces to hold the post in the hole. If you are installing several posts, such as for a deck or fence, you can make braces out of 2-by-4-inch lumber.
  • Concrete products are extremely caustic. Always wear protective clothing, gloves and goggles when working with concrete.


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