How to Replace Rotted Deck Posts

D eck posts are the silent sentinels of your outdoor space, bearing the weight of every barbecue, party, and quiet morning coffee. When rot takes hold at the base—usually due to prolonged ground contact or trapped moisture—it isn't just an eyesore; it is a structural failure waiting to happen. Ignoring a compromised post can lead to uneven decking, sagging rails, and a complete collapse if the beam shifts. Performing this repair is a test of patience and physics rather than sheer strength. The goal is to isolate the post from the load it carries, remove the damaged wood, and reset a new, rot-resistant post on a solid base. When done well, the new post will stand perfectly plumb, tied securely to the beam above and the footing below, ready to support the structure for another decade or more.

  1. Expose the damaged post. Remove any lattice, trim, or decorative skirts surrounding the deck base to expose the post. Clear away dirt, mulch, or gravel from around the footing to ensure you have a clean surface to work on.
  2. Jack up the beam carefully. Place a hydraulic jack on a flat, stable block of wood positioned safely next to the rotted post. Use a secondary 4x4 or 6x6 support post to transfer the weight from the beam to the jack, lifting it just enough—about 1/8 inch—to take the pressure off the existing post.
  3. Extract the rotten wood. Unbolt the post from the top beam and the base bracket using a socket wrench or impact driver. Once disconnected, pull the rotted post out, using a pry bar if it is stuck in the bracket.
  4. Check the foundation first. Check the concrete pier or footing for cracks or levelness. If the concrete is crumbling, you will need to patch it with high-strength concrete filler or replace it entirely before moving forward.
  5. Install the new post plumb. Measure the distance from the footing bracket to the underside of the beam exactly, then cut a pressure-treated post to size. Place the new post into the bracket and secure it using hot-dipped galvanized carriage bolts.
  6. Lower the beam back down. Slowly release the hydraulic jack to return the beam's weight onto the new post. Reattach any decorative trim or lattice you removed earlier.