Most homes have either I-beams (steel) or wood beams....those built after WWII generally have I-beams, sometimes supported just on the outside perimeter blocks or sometimes also on interior posts. The purpose for using them is to eliminate the need for interior posts in a basement. However, I don't believe they have any affect whatsoever on water intrusion, and they ARE part of the structural integrity of the home. I'm no construction manager or general contractor, but have rehabbed 4 homes of varying age with my husband. If the home has an I-beam (steel) and there's some sort of structural problem, your best bet would be to get a structural inspection by a certified structural engineer or ask the seller to have one done.