When you are on your first greenhouse mission, what you should do is to build a cheap greenhouse rather than one which requires substantial investment. Although building a greenhouse with inexpensive material like PVC and polyethylene needs you to have only very basic hands-on skill, you would still find it a challenge to meet all the requirements unique to your weather.
You can build a cheap greenhouse with PVC pipes for framework and some lumber for support at the base, the end walls and the doors. The lumber you use should be treated or painted. Schedule 40 one-inch PVC pipes can be used to make the ribs and the central ridge on the roof. Use the same PVC pipe to make purlins that run the horizontal length of the greenhouse on both sides. The height of the purlins should be at the half way mark between the central ridge line of the roof and the ground directly below.
To make the base, simply mark out the area and pound in rebars at the corners. Now, pound a three foot rebar every four feet along the length of the structure. You should end up with paired rebar pieces on both sides of the greenhouse length. Attach the PVC pipes meant for ribs. You can use 25 foot PVC lengths to make the ribs for a 14 foot wide greenhouse. The number of ribs will depend on the length of your greenhouse.
Now, slide the PVC pipes over the rebars at opposite ends. Check that the rebars are securely held in the ground, are straight and properly aligned before you slide the PVC pipe onto them. Place suitable lumber along the outside of the ribs all along the length to get a surface to attach the ribs to. Use tie wraps or fence staples to secure the ribs in place.
To fix the purlins to the ribs align the PVC to the ribs, drill apposing holes and use tie wraps to secure together. For the central ridge you should drill holes and secure the PVC pipes in place in a similar way to keep the ribs from shifting.
For the side wall, use lumber to make the support for the door frame by fixing a horizontal beam across the two ends of the outermost rib. Drill through the wood and the pipe and tie with tie wrap. The height of the beam should be the same as the height of the door. Place vertical wooden pieces to provide the support frame for the door. The top of each vertical piece should be nailed or screwed to the horizontal beam while the bottom portion should be driven into the ground to at least half to one foot. Make the door to fit snugly into the support frame so that no gusts of wind may inflate the greenhouse.
Now, attach the polyethylene film with tie wraps or staples over the structure. Secure at the base by pushing it under the lumber at the base. Congratulations! Can you think of an easier way to build a cheap greenhouse?
