post depth

[Simpso]

Hi everyone I have a 2 m pressurised wooden post I want to sink into the ground and surround with cement.
Does anyone know how far into the ground I should go so the post is stable? I was thinking 400mm.
Also will surrounding in cement help with stopping the post rotting under the ground?
Thanks

 

[wrathkeg]

I would put about 600 mm in the ground for a 2 m post. Surrounding it with concrete might help prevent rot, but it will still rot eventually. You might want to soak the end of the post in wood preserver.