Steel pilings can be installed by cutting holes in your floor and then digging down beside the interior grade beams.  Of course, this is terribly messy, and can destroy expensive tile and wood floors. An alternative is to dig tunnels under your home and install the pilings from the tunnels.  This is the advantage of the short section steel pilings.  If tunnels are used to install interior pilings, you can stay in your home while the work is being done and your floors will not have holes cut in them!