Setting Cedar Fence Posts That Won’t Rot

Updated: Feb. 07, 2024

Keep moisture and insects from destroying your cedar fence posts.

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Cedar has a reputation for durability, but unless a few guidelines are followed, cedar posts can fail in as few as five years. Three factors contribute to this early failure: poor drainage, low-quality wood and poor protection against insect damage. Here's how to install new cedar fence posts and avoid the problems that made your old posts rot.

Tools Required

  • Bucket
  • Caulk gun
  • Paintbrush
  • Posthole digger
  • Shovel
  • Trowel
  • Wheelbarrow

Materials Required

  • Acrylic caulk
  • Aggregate
  • Cement
  • Wood preservative

Project step-by-step (5)

Step 1

Pick the Right Posts

  • Wondering how to set fence posts that won’t rot? Step one is to select the kind of wood you’re going to use. The key to proper fencepost instillation is to use the right kind of wood. Don’t use posts that contain sapwood. Instead, use heartwood, because it’s denser and more insect-resistant. We recommend a sturdy cedar fence post.

Step 2

Treat the Post With Preservatives

  • When learning how to set fence posts correctly, you need to make sure you understand how to preserve the posts. Prior to installation, soak the bottom of the posts in a wood preservative containing copper napthanate, such as Cuprinol.
    • Note: Available at some paint stores and home centers, this wood treatment is specifically designed for in-ground applications.

Step 3

Insert Aggregate

  • Once you’ve dug your hole, place about 6 inches of aggregate in the bottom of the posthole to allow for drainage. This will minimize the amount of water that comes into contact with your cedar fence post.
    • Pro Tip: The bottom of the post should extend a few inches into the aggregate as shown.
Step 4

Pour in Concrete

  • After you’ve got your aggregate in, it’s time to pour in the concrete.
  • Concrete should be 2-3 inches above the soil level. This gives you the ability to shape the concrete around the fence post base a bit.
  • Trowel the top smooth and slope it so that water runs away from the post. You don’t want water to have an opportunity to pool around the base of the fence post, or else you’ll be right back where you started.
Step 5

Caulk Around the Fence Post Base