Casting on an existing plinth to make it higher?

[Klicka]

I have a post that stands on a pier. The post is secured with a post base. The post supports a gable balcony.

The problem is that the post base is so close to the ground. The post is rotting. Is it possible to raise the pier by casting about 10 cm extra on the old pier? Is it ok to cast in the old post base (as reinforcement) or should I try to cut it off and maybe drill in other reinforcement?

 

[KnockOnWood]

I think it would be much easier to switch to a pressure-treated post.
Like this one for example:

https://www.byggmax.se/95x95-impregnerad-stolpe-grön-p08795095

 

[Klicka]

This is what it looks like. I have dug out the foundation today. I would prefer to raise the foundation because the post base is way too low.

I was thinking if I could just put a form tube around the existing foundation and cast.

 

[Avemo]

It should be quite well prepared. If the old stolpsko remains as reinforcement, it is unlikely to come loose easily. You might want to remove some of the sheet metal to facilitate filling with concrete under the sko.