Better to dig out the old post and put in a new one.
Casting a post in concrete will accelerate rotting, by
trapping water around the area where the post goes
into the concrete, and will be more work next time.

With the tops: You might just trim down the rotted
tops if there's room. You could also do a cap, like Nestork
said. Or you can leave them. It probably wouldn't hurt to
put a drain hole in, either. I'm guessing this is cedar
stockade fencing that's quite old. Eventually you'll have
to replace those posts but they take a long time to rot
out.



| Fixing wood fence posts, 2 questions
|
| I have a wood picket fence, 44" high, with about 35 fence posts, round,
| 4" in diameter iirc.
|
| I have two problems.
|
| 1) One is loose. It feels like it has broken off maybe 8" above the
| bottom end. How to fix it????
|
| I thought I would disconnect it from the fence, pull it out (which I
| think will be easy), take a replacement (easy to find), cut it to the
| same length as the piece that comes out**, put the post in plus some
| instacrete or sackcrete***, pour in some water, and let it harden.
|
| Is that okay? If the part of the first post every rots away, and the
| post sinks, I can replace it again.
|
| **Well actually I would put the new post in and use it like a pile
| driver to crush the old post stub as much as I can. Then extend a
| string from the posts to the left and right of this one, and mark this
| one so it's the same height as the other two.
| *** (the speedy stuff or the regular stuff both work, I hear)
|
|
| 2) Some of the posts are hollow in the top center, going down 2, 3 even
| maybe 4 inches. . Water sits on them and the wood rots or crumbles.
| Sometimes green plant life grows in the holes
|
| a) I thought I should drill a hole in the side so the water drains out.
| or
| b) I should fill the holes with something, something that looks like the
| original post if possible. . I had tried outdoor wood glue mixed with a
| lot of sawdust. but that broke up.
|
| Suggestions?
|
| Thanks.