The largest Sunshine Greenhouse - 8' wide and standing almost 10' tall there is plenty of room for growing (and more). These kit comes in either 8' long, 12' long or 16' long sizes. You can also add 4' long extension kits if you have more room to work with.
Mt. Hood kits are 6' wide and 8'4" tall at the peak. Narrow enough to fit in a limited space it comes in 6'x4', 6'x8' and 6'x12' lengths.
The lean-to structure is designed to attach to a smooth vertical wall. Exterior dimensions are 4' 3'' wide by 8' long and 7' 3-1/2" high, sloping to 5' 6-1/2". The lean-to has two doors, one at each end. No automatic ventilation is built in.