Actually, I like the second approach. But it would require welding on a base plate to the existing columns, then bolting the plate to the new concrete with expanding anchor bolts.

In both approaches, there should be some tie-in of the new concrete into the existing footings. Just resting new columns on top of the old ones does nothing to resist lateral forces.

Hmm. Not sure that would be within my diy skills. If I hire someone I want to make sure they are doing the job right. How would be best to tie the new concrete in? When looking at the posts I do not see any concrete but it could be there as there is black plastic covering the dirt of the crawlspace. I should be at the house tomorrow and can look.
What questions should I ask any contractors to ensure they are going to do the job correctly?

Typically, rebar would be epoxied into holes drilled in the pads; then you install forms for the new column pours. (Properly sized Sonotubes would be easiest to use.) You can mix the concrete yourself; the bagged products can be used, but be sure to follow directions to obtain sufficient strength.

When I've needed as little a yard, I've called ready mix companies, then met the mix truck where they're pouring a foundation. They turn the spout on the truck and fill my plastic lined utility trailer.

But this only works if you're not far from your site and can move quickly. Otherwise, you'll end up with a solid block of concrete in your trailer!

It's like many home construction jobs: a combination of hard dusty work in cramped areas but that still requires precision and foresight.

Note: you can pick up the steel plates at a steel fabricator. And since the pads will be under water at times, I'd use epoxy coated rebar to tie the new concrete to the old.

This post was edited by worthy on Mon, Apr 7, 14 at 0:27