Stage 4 – Preparing the PVC columns and arches
Stage 4 comprises the preparation of the 4-inch PVC pipes to be used as the greenhouse columns and the 2-inch PVC pipes for the greenhouse roof.
The 4-inch PVC columns are filled with an iron trellis (Photo 33), but an 8 mm iron bar can also be used in places subject to strong winds. The iron trellis or bar is meant to reinforce the interior of the column, which will be filled with concrete. Cut the 4-inch PVC pipes and the iron mesh and/or bar to the same measurement, i.e., 3.70 meters each. The greenhouse requires 32 PVC pipes and iron trellises and/or bars. After measuring the pipes and trellises, cut them (Photos 33 and 36). Next, place the cut iron trellises and/or bars inside each one of the 4-inch PVC pipes (Photos 34 and 35).
Then, cut the 2-inch PVC pipes that will be used to make the top structure of the greenhouse, the roof arches. Cut the 2-inch pipes to the measure of 5.20 m long (Photo 37). For the roof we will need 16 two-inch PVC pipes. Then cut sixteen 8 mm iron bars to the measure of 5.30 m long (Photo 40) that will be used to reinforce the internal structure of the curved roof arch. Please note that the connecting extremity of the 2-inch PVC pipe must be cut off (Photo 38) to allow for the two extremities to receive 45-degree couplers (Photo 41). Next, bend the 8 mm iron bar already placed inside the 2 inch PVC bars to 45 degrees (Photo 43). Connect the 45 degree couplers to the two extremities of the 2 inch PVC pipe with the 8 mm bar inside (Photos 43, 44, 45 and 46).
After connecting the two 45-degree PVC couplers at the ends of the arches, proceed with the bending of the arches to the right curvature (Photos 47 and 48). After checking the curvature, fasten the arch with wire (Photo 49). After tying all the arches with wire (Photos 50, 51 and 52), they should all have the same curvature to allow for a uniform coverage of the agricultural greenhouse, with the 8 mm iron bar inside the bent arch (Photo 53).
The curvature angle should be enough to keep rainwater from being retained on the greenhouse roof.
Materials required for this stage: iron cutting saw, PVC cutting saw, wire, and piece of iron pipe (for bending the 8 mm bars that go inside the arches to make 45-degree angles)