This is the greenhouse that my husband constructed for me. It is built on 4x4s with 2x4s for the framing. Our only mistake was in using one layer of panels; we should have used at least 3. Also, although we had a ventilation fan, we didn't get it installed before we moved. I used a radiator-style space heater for heat. There is a 3' wide walkway down the center and shelves made from wire mesh on the sides.