Pressure-treated lumber is infused with a chemical preservative that extends the life of the wood. The lumber is rated by the retention of the chemical product in pounds per cubic foot. The higher the rating numbers, the better the decay resistance. Posts made of pressure-treated wood are often used as the structural basis for wood fences, with the post secured in concrete. Pressure-treated wood placed into concrete needs a minimum rating number of 0.40 or greater.
Things You'll Need
- Posthole diggers
- 24-inch level
- 1-by-4-inch wood, 6 feet long (for bracing)
- 16p nails
- 1-by-4-inch stakes, 2 feet long
- Concrete mix
Dig a posthole to set the pressure treated wood into concrete. Use the 1/3-rule to determine how deep to dig the hole. The 1/3-rule states that 1/3rd of the post is buried relative to the overall length of the pole. For example, a 6-foot pole is buried 2-feet below the surface. Once the correct 1/3-rule depth has been calculated, dig the hole 6 inches deeper than is needed for the overall height of the pressure-treated wood post.
Fill the lower 6 inches of the posthole with gravel. This keeps water from collecting near the bottom of the post and being wicked up inside the treated wood. Set the treated post into the hole on top of the gravel.
Attach two pieces of bracing wood to the post. Position the braces three to four feet from the ground amd 90 degrees apart. Secure the braces to the post by driving two 16p nails halfway through the braces.
Pound the wooden stakes into the ground approximately four feet from the post and in line with the braces.
Level the post on both sides, 90 degrees apart, using the 24-inch level. Secure the braces to the wooden stakes with nails when the post is level. The braces will hold the post level while setting the concrete.
Mix the concrete according to the label directions. Fill the hole around the treated post with the mixed concrete. Extend the concrete one to two inches above the hole, then slope it away from the post so water will drain from the wood.
Let the concrete cure for 24 hours. Remove the braces and wooden stakes.
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