This Greenhouse is a 17ft by 12ft. 
It is made from old *METAL* doors that were removed from homes being remodeled or demolished. 

All doors were either paid to remove and install new doors, ~* I’m a Home Improvement contractor* ~
Some old doors were given to us for free. 

The doors are screwed together using old recycled free boards and NEW screws. Support boards go on interior and are screwed at the seams of the doors where they join together.  Pics will be posted. to view. 

Then a support board runs from side to side joining each side together to keep from racking and moving. Currently, it is just the doors lying on the ground. It is not perfectly level and square. 
        ** IF YOU LIVE IN A WINDY CLIMATE. ** 
    You should use T-posts and shove them into the ground on the corners. Before installing the second layer of doors, help ensure they are securely attached to the ground. 
         **THIS IS NOT A DESIGN TO LAST FOREVER* 

  Why wouldn’t it last a long time? 

  Well, let’s answer that with, we are using recycled materials that are already aged. Most of the door ages are unknown. All but 2 are metal doors.  So with this said, keep in mind that in YOUR design and with my design, it is a project that will require maintenance over time. 

  You might have to replace a door. But with this design. you can replace 1 door no matter its location by undoing screws and replace the door, and then install the screws into the new doors. Even where the cattle panels meet the top. as they are U nailed to the top boards. which are only screwed to the doors. 🙂 Yeah, great design. I was thinking ahead in case a door rusted out. 
will insert pics. 

     As can be seen at the top, where I did the window. It was a box framed to fix the window I currently have not in the greenhouse during the hot seasons. I have a metal screen stapled with trim boards. For now, I just put the window in the frame with two little screws to help hold it in during cold seasons. No, it’s not air-tight yet. tiny gap around the window frame. And for the other end of the greenhouse, I am going to do the window and screen the same design, depending on the air flow direction, will have a solar fan. So during the day, the fan will run on free energy, we don’t keep much in it during the hot summer days here in North Middle Tennessee, as it gets too hot, and most plants do not like that heat. I am working on a PVC pipe design to maybe roll the top off during the summer months and have some tropical fruit trees and an aquaponics fish pond in there. Then use a Jean paine, mixed with a rocket mass stove design to help heat the greenhouse a little during the winter months on them really cold days..  

The glass has been spray-painted white. just a mist coat so the sun is not magnified so much through the glass.  I found it was too hot, and with the white mist painted windows, it’s been great all year round so far. 

That project will be updated at a later time. 

Here are the Greenhouse tarps I am using for the top.  ** Affiliate links below **
   

    More to come on the greenhouse project. Like adding shelving, gutter hydroponics system, catfish aquaponics, tropical fruits, Jean Paine composting heater, rocket mass stove, many projects ahead for the greenhouse.