If you've done much moving of your portable farm building, you may have found weaknesses developing after several of such moves. Moving any building- portable or otherwise- develops severe vibration and racking stresses in the building. This eems to be one of the most important factors limiting the years of service of your portable buildings.
Morford, V. J.
"Make Portable Buildings Last Longer,"
Iowa Farm Science: Vol. 6
, Article 4.
Available at: https://lib.dr.iastate.edu/farmscience/vol6/iss6/4