My father is a structural engineer and he designed our greenhouse to meet code. The cost of the lumber, nails, concrete, bench materials and other permanent parts cost only a few hundred dollars. The shade cloth and plastic covering is replaced as needed and the cost is ongoing. Our side walls are only covered in plastic during the winter, in summer itís just shade cloth - except for the north wall and the roof, which are covered in plastic year round. We got indirectly hit by two hurricanes. Our greenhouse was exposed to 100mph winds twice in a two week period. No damage. Not even torn plastic or shade cloth. Mind you, trees were being uprooted, the roof came off part of the airport, and our little greenhouse didnít even feel it.
Thereís never enough room. No sooner do we build the greenhouse do we fill it up and now it needs to be expanded. If anyone out there wants to build their own greenhouse, build it WAY larger than you think youíll need.