We are residing our house because of hail damage, so I needed to remove the railings on the front porch. When I got to the corner support post, I found that they used standard 2 x 4’s nailed together with cedar trim boards nailed to the 2 x 4’s.

It looks like the porch was poured in two sessions. First the base. When this had set they installed the corner post and the siding on the house then poured another 4 inches on top of the base. I now have a support post that is rotting out at the bottom where the 2 x 4’s are in the cement and I have siding behind the concrete on the front of the house.

Question: Can I just cut off the bottom 4 feet of the support post and install a 4 x 4 treated post and fasten the two together with metal plates or do I need to remove the whole support post and install a new treated post?

What are my options regarding the siding? Do I need to remove the concrete along the house to expose the siding or is it ok to just cut the siding flush with the concrete and install the new siding around the porch floor?

I would probably support the porch, cut off the post where the wood is still solid, box around the post hole and fill with cement raising the new cement above the porch floor so the water will not get to the wood again and also install an anchor bracket. Once that all sets up replace the end of the post and anchor into the anchor bracket.