Project Guide: Setting Posts Below Grade

Setting Posts Below Grade

After you’ve laid out the location of the support posts for your deck, playset, or other outdoor structure, you’re ready to begin creating the foundations for the posts. This project guide demonstrates one way to correctly set the posts in a concrete footing.

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Steps 1 - 4 of 4

Step One

Dig postholes.

Use a posthole digger or power auger to dig holes at the marked spots. Dig at least 6 inches deeper than half the exposed height of the posts. For example, a post that’s 8 feet tall needs to sit in a hole that’s 4 feet 6 inches deep. Shovel in 4 inches of gravel, tamp it, pour in a 6-inch layer of concrete, and let it dry.

Step Two

Align the posts.

Retie the mason’s lines and slide them on the crosspieces to mark the outside edges of the posts. Set each post into its hole, plumb it with a fence post level or regular level, and brace it with 1×4s and 2×4 stakes.

Step Three

Mix concrete.

Mix bagged concrete in a wheelbarrow. Start by making a crater in the dry ingredients. Pour in about half the water recommended by the manufacturer. Mix with a mason’s hoe, then slowly add the remaining water until the concrete has the consistency of oatmeal.

Step Four

Fill the holes with concrete.

Pour the concrete and work a 2×4 up and down in it to remove air pockets. Slope the top of the concrete so water drains away from the posts. Let the concrete cure for two to three days.

Steps 1 - 4 of 4

	Tools
	Tape measure Spade
	Saber saw Hammer 3-pound sledgehammer Level
	Wheelbarrow Clamps Posthole digger Mason's hoe Work gloves Dust mask
	Not available online
	· Plumb bob · Safety goggles