I have built piers on different jobs. Steel framing is far superior to any kind of wood because steel is stronger and welds do not move like bolts, screws, or nails. Because of the strength of steel vs. wood you can span larger areas with fewer supports and bracing, consequently fewer materials are needed. Deck the steel frame work with wood and you have a structure that will be around a very long time.
Nick Jones
www.soilmovers.com