I made mine out of cattle panels and greenhouse plastic film. At the time I lived in upstate NY in zone 4b. To build it I started out by building the kneewalls. Kneewalls are just that. Walls the height of your knees. I had 4 x 4's in the corners and these went down 3 ft into the ground and had concrete poured around them. They anchored the GH as well as supported the structure.
Next I bought 4 cattle panels. I'm adding a jpg from a store sight to help those of you who've never seen them visualize them. The panels are 60" tall x 16' long. They run about $18. each I attached these to the kneewalls so they formed a vaulted ceiling for the GH. I used plumbers metal straps screwed into the kneewall to hold them down and then used zip ties to attach them to each other. Once all 4 were up the next step was to frame out the end walls and cover with plywood. The far end had an opening for a window. The near end was framed for a door. After this came the plastic. I purchased this from a greenhouse supplier. I had to throw it over the top of the GH and this wasn't easy cause it stood 7 ft high. So I attached twine and pieces of brick to the twine. Threw this over and then used the twine to pull the film over the top of the GH. Once it was in place I had to scramble to fasten it down before the wind undid my work. I stapled it to the sides pulling tauntly as I went along. Then I took long 2 x 2's and rolled the excess film on each side and screwed through the whole thing into the knee wall. At the ends I pulled the film over them and stapled to the plywood then reinforced this by taking strips of wood and screwing through them into the plywood. At this point it was all somewhat weather tight so I moved to the inside. I dug a small trench and hole for the electric wire to run out and then wired it to a junction box. From the box I ran wires to 4 outlets. Two at each end of the GH on opposite sides to each other. The wire from the junction box went back to an outside outlet that had in a former life run a pool pump. This was on a breaker all by itself so no overload.
Back inside I put down lanscape fabric to deter weeds followed by builders sand and topped it all with gravel.
Next came installing the window and then the door.
Now because of my cold climate I needed to insulate. The north side of the GH doesn't allow much light so I covered the entire side with rigid foam insulation. I also used this for the remaining kneewalls. Over the kneewalls I put lightweight plywood.
Then came the bubblewrap all over the inside walls. Zip ties held it up and attached to the panels. On the walls my staple gone did the job.
On the north wall I added a layer of mylar which insulated and reflects light. You can get mylar where they sell camping supplies for about $3. They're like an aluminum blanket that keep you warm.
At this point my GH was almost ready for plants. I had some barrels which I painted black and after placing them where they would be holding wire shelves I filled them with water. I'm told they would retain heat during the day and give it off at night. I was never really sure they did much to heat the GH and don't plan to use them when I build my new one.
For heat I used a variety of things. Electric 1500 watt heater ($15. Walmart) when temps were in the 40's and 50's, once it dropped below that I used a kerosene heater (might be a problem for anyone growing tomatoes) and a propane blue flame instald in a corner. The door was a regular kitchen metal door with the top half double pane insulated glass.
I used cheap $10. fans One at each end of the GH facing in opposite directions to have good air circulation. Then came the shelving. I bought Closet Maid plastic coated shelves and put them over the barrels. Where they needed more support I built long rectangles of wood to hold them and act like legs.
Then came the plants.
The rest is history. For under $700. I had a greenhouse that was 7 h x 8' w x 17' long. I had it for three years and it survived windstorms of 70MPH winds.
I had a florecent fixture for light but mostly so I could work in there late into the evening and if I needed to check things after dark.
Problems:
the ceiling often collected water from air moisture and had to be helped out manually
the propane heater had a habit of going out when it was coldest and in the middle of the night. I had to add a vent for it to get more air.
I feel the barrels ate up more space and did not contribute enough heat to justify the space they used.
MollyD
