Thank you Bryan for your recent inquiry with The Home Depot for 5-1/4 in. x 5-1/4 in. x 8 ft. Porch Column, White. This item is not available at the moment. You can however, visit your local store to see if a special order can be placed for you. We appreciate your business and look forward to serving you in the future.
Not knowing what kind of environment your posts are exposed to, I really don’t have a clue why your post rotted. If you painted it when you installed it, there must be something specific to that one post if the other is ok.
No, it doesn't come in 9 ft.
Yes, I purchased a fiberglass post seat that incorporated venting passages and a mean of anchoring the post down to my concrete slab. It took less than 1 hour to install.