Originally Posted by RocLok
Looking at your other post, it looks like you have a lot more than steel VS concrete going on. If the old foundation was built on dirt that you are removing, that is not good. First thing is to make sure to shore up any areas that you are modifying.
Due to the fact that you are risking the loss of your house completely you will definitely need to talk to an engineer and figure out how to hold your house in the air after you remove it's support. Look at it this way, it may cost you a few thousand dollars to have an engineer help you, or it could cost you your house, your possessions hopefully that is all if you do not support it correctly.
Thanks for the reply. I'm actually not modifying my existing foundation. I'm digging the crawlspace deeper while staying away from the existing footings a safe distance so as not to undermine the footings. I did have an engineer look at it, and he said I need to stay clear of the 45 deg. slope from the bottom edge of the footing. In most places, I'm staying away even further than that just to be safe.
He also told me to duplicate the existing column footing dimensions when I install the steel posts. However, I'm wondering whether the narrower steel columns require a deeper footing than the wider masonry.