Would it rot even with concrete under and around it, and protected with a painted trim? My impression is that the existing post has only rotted because it was left unprotected at the bottom, and its been in place for 30 years. The extension is raised so water doesn't tend to sit around the base. I'd bow to your judgement on this.
Thanks. Makes sense. Just a bit nervous about steel as I don't really know what I am doing with that, or how it would interact with what is already there, and how it connects to the doors etc. Will need to do a bit of research.
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