Originally Posted by
Mendip
By columns do you mean the reinforced concrete poles/posts that form the framework of the house?
If so, I don't think exactly matching with the pile size matters too much.
When we built a house, 9m deep friction piles were first installed, which were then tied in to the foundation reinforced concrete footings that were approximately 1m cube (maybe a bit less). The reinforced concrete columns were tied into and built up from these concrete footings. I can't see that it matters if piles and columns are exactly the same size. Sorry about my terminology if wrong.
By memory, the metal friction piles were H-shaped and required in case of heave/subsidence (we are on clay soil). I would say that the concrete columns built up from the foundations were similar in size, but probably a bit larger than the metal piles. If in doubt, I would go for the 22 x 22 if the price isn't too much more.