Last Updated: July 28, 2016 There has always been a debate of whether or not a corrugated steel bunker is superior to a steel, square underground bunker. For many years, it was thought that the rounded, ribbed piping was the best for manufacturing large underground bunkers; however, as engineering has developed innovative ideas of creating stronger structures, it felt only natural to take those developments to a higher, or in this case, a lower, underground level.A corrugated pipe, when placed underground, has one point of pressure to which any dirt that is thrown on top must bear the brunt of. You’ll rarely, if ever, see a supporting beam or walls that help support the curved walls of the steel cylinder to keep it from collapsing under the weight of the earth above. However, in our Off The Grid… affordable underground bunkers, we have structural angle and channel reinforcements, as well as a tubular exoskeleton for extra support. The weight of the world is literally spread over the entire unit, unlike the rounded pipe bunkers of old where the top pressure point is expected to withstand the weight.