How to Pour a Concrete Post

Concrete posts will last a lifetime. The procedure is identical to pouring concrete columns and pillars, except that the scale is much reduced. The finished product will be an 8-inch square post that stands 6 feet high.

Things You'll Need

• Garden sprayer
• 1 gallon bond breaker
• 4 3/8 by 68-inch rebar
• 28 3/8 by 6-inch rebar
• Tie wire
• Lineman's pliers
• Framing square
• 12 2 by 4 by 12-inch lumber
• 4 1/8 by 8 1/2 by 72-inch plywood
• 6d smooth-shank nails
• Hammer
• 4 3/4 by 72-inch chamfer strips
• 4d-finish Nails
• 16d double-head nails
• 4 2 by 4 by 96-inch lumber
• 4 2-foot forming stakes
• 1 1/2 cubic yards concrete
• Concrete vibrator
• Concrete finishing trowel

Instructions

Build a Concrete Post

1. Fill the garden sprayer with bond breaker, and pump the handle to achieve a pressurized flow. Spray each board evenly with the sprayer. Allow the compound to dry for at least 2 hours in direct sunlight. Repeat the process two more times to ensure all interior form surfaces are well-coated.

2. Build the rebar rack by tying two long pieces of rebar at top and bottom with 6-inch rebar shafts. The ends of the short pieces should extend 1 inch beyond the long pieces they are tied to. Tie additional 6-inch pieces every 12 inches along the length of the rebar. Use 7 6-inch pieces, one at each end and the rest spaced every 12 inches along the length. Repeat this process for the other two long pieces of rebar.

3. Form a square rebar frame by tying the two sides you have already made together with the remaining 6-inch pieces of rebar, in the same manner as in the previous step. Use the framing square to set the corners so that the sides connect into an equal-sided square. Stand the rebar frame up on the foundation where the post will be poured.

4. Center two of the the plywood strips on the 12-inch pieces of 2 by 4. Nail through the plywood with 6d nails, into the edge, or narrow sides of the 3 by 4 material. Place one 2 by 4 at each end, and one in the middle. Use two nails per board, evenly spaced across the width of the plywood. Use finish nails to tack chamfer strips along the length of the plywood. On one side, the strips will be flush with the edge, and on the other side the chamfer strip will be inset 1/8 inch. Nail the strips every 12 inches along the length of the form.

5. On sides of the foundation, stand up the two sides you have just prepared. Place the remaining pieces of plywood so that the concrete side of the plywood butts up against the chamfer strip on both sides. Using three of the 2-by-4 pieces and duplex nails, nail through the wood and into the 2-by-4 pieces already attached to the plywood form sides. Be careful to keep the joints at a 90 degree angle. Repeat the process for the final piece of plywood. Check the square of the form, and make sure that all sides are equal and the rebar cage is centered inside the form.

6. Attach one 8-foot 2x4 brace at a 45-degree angle to each side of the post you are pouring, and nail them to stakes to keep them in place. When you pour the concrete, these braces will hold the form in place. If your form is not stable, you may need additional braces and stakes.

7. Pour the concrete slowly, using the vibrator continuously. Place the vibrating head inside the form, and vibrate around the rebar as you pour. The concrete must be well vibrated to fill all voids. Finish the top of the post with a flat or domed top. Allow the concrete to cure for at least four days before removing the form.

Tips & Warnings

• You cannot use too much bracing. The number listed here is the bare minimum that will work, but some installations may require twice as many. The formula for calculating concrete is L(ength) times W(idth) times H(eight) divided by 36. Use inches for the calculation, and the result is the cubic yardage you will need to order. When the form is removed, apply Portland Cement to fill any voids or bubbles.

References

• All About Nails
• Concrete Bond Breaker

Resources

• Concrete Supplies