In this video, Ask This Old House landscape contractor Roger Cook repairs a decayed fence post.
1. Use a reciprocating saw to separate the rotted post from the fence. Cut through the post directly above and below each of the three horizontal fence rails.
2. To expose the fence rails, use the straight claw of a framing hammer to chop out the wood in between the reciprocating saw cuts.
3. Move to the back of the fence and extract any nails or screws that are securing the rails to the rotted post.
4. Remove one section of fence, then pull out the rotted post.
5. If the next post is rotted, repeat the previous four steps.
6. Use a manual posthole digger to clean out and excavate the old fence-post holes. Be sure to remove any remnants of the old rotted post.
7. Stretch two taut nylon strings across the fence line. Position one line at the tops of the posts, and another line to represent the face of the posts.
8. Drop a new fence post into the hole and check it for plumb with a 4-foot level.
9. Slide the ends of the three horizontal fence rails into the holes in the post.
10. Repeat the previous two steps to install a second post, if necessary.
11. Set the fence panels in between the new posts.
12. Check each fence post for plumb, then backfill the postholes with pack, which is a mixture of ¾-inch stone and stone dust.
13. Add about 6 inches of pack, then tamp it down with a long 2x4. Add another 6 inches and compact again. Repeat until the postholes are completely filled with compacted pack.
14. Secure the new posts to the fence rails with 3-inch (10d) galvanized nails.
15. Remove the two nylon strings.