Back in England we had built a concrete shed (which housed a gym, as well as storage for all our spare junk). After having moved to USA, getting married and having 2 kids, too many medical issues to list and now finally in the final steps of buying our own house, I'd like to have my own gym built again, but I'm unsure what would work best.
One made of cinder blocks costs more initially, but is structurally far more stable and won't require nearly as much upkeep. A wooden structure would cost less up front but probably won't hold the heat in as much as cinder blocks would (planning no electricity to said gym, probably just a propane tank heater for winters).
I'm not sure how a wooden structure differs from cinder block in terms of moisture getting within the building and its effect on iron/steel, or how warm/cold/humid it'll get through the year. Overall aesthetics of the interior & exterior aren't a real concern, so I'm not letting that be a driving force in my decision.
Any helpful advice would be appreciated.