Hoop greenhouses are known as high tunnels in gardening publications. The hoop house is an inexpensive structure that may be either temporary or permanent. The structure may be made of materials that you find in a hardware store such as PVC pipe and construction plastic, or you can purchase high-quality ultraviolet-resistant PVC. Depending on the quality of materials that you use in your greenhouse, the structure may last a single season or up to four years before you need to replace or rebuild the greenhouse.
Lay out the foundation of your greenhouse with a measuring tape and rope. Hammer stakes into the corners of the marked foundation. Stretch string between the corners to mark the location of the frame's walls.
Place recycled railroad ties onto the ground around the perimeter of the greenhouse, so the outer edge of each tie aligns with the string that marks the edge of the greenhouse. The ties should touch one another at the corners to form abutting joints.
Determine how many ribs you would like to have in your greenhouse. Divide the total number of struts based on the total length of the greenhouse. Then add another strut for the greenhouse wall. Many greenhouse builders prefer to place a framework strut every 4 feet along a greenhouse. For a 24-foot greenhouse that is 12-feet wide, there would be 7 struts.
Mark the location where your struts will anchor to the foundation timbers in chalk. For example, a 24-foot greenhouse will have marks at either end of the wall timbers and at 4-foot intervals down the length of the timbers.
Attach a pipe anchor clamp to the timber at each point where the ribs of the greenhouse frame will connect to the timber. Do not tighten the clamp all the way.
Slip the end of a 12-foot PVC pipe into each clamp along one side of the greenhouse. Flex the pipe into a U-shape and slip the other end of the pipe into the clamps along the other side of the greenhouse frame.
Tighten down the pipe clamp.
Climb a ladder on one wall of the greenhouse. Tie a 24-foot piece of 9-gauge wire to the topmost point in the arch of the rib. Run this wire over the top of the greenhouse. Secure the wire to the topmost point in the arch of the rib on the other end of the greenhouse.