Hello. I am planning to turn my crawlspace into a basement. (A full description is here: http://www.houserepairtalk.com/f39/new-amateur-project-11441/) My 5 existing masonry columns do not go deep enough. Since I need to replace them, the engineer I hired said to go with 4" steel columns. However, I am not sure where I can buy them. I see the adjustable columns all over the place but not the fixed length columns with weldable endplates. It looks like this is something I need to get from a building supply store that caters to professional builders. Is that right? Thanks in advance for the help.