If you’re going to build a hoop greenhouse, using PVC pipe is an easy, low cost alternative to greenhouses that are built from wood or other materials. PVC, or polyvinyl chloride can be purchased from your local hardware stores or home builders like Lowes and Home Depot. PVC is light, strong and inexpensive and easy to work with for beginners.
Follow these simple steps to build a hoop greenhouse and you will end up with a nice, sturdy, and inexpensive hoop greenhouse.
1. Build a ground frame: To build a hoop greenhouse start by building a four- sided ground frame from rot-resistant wood. Place 2 x 6’s on their edges for houses 14-18 feet wide. For smaller houses use 2 x 4’s.As long as opposite sides are equal length your corners will be 90 degree angles. To prevent the frame from slippage drive in temporary stakes on the outsides of the frame.
2. Drive ground pipes: These pipes are 18 – 36 inch long stakes pounded with a sledgehammer into the ground. Put one at each corner and another every 3 feet. Each pair of ground pipes will support hoop pipes. All ground pipes should be the same height.
3. Raise the hoop pipes: These pipes create the arch of your hoop house. One 10 foot pipe and one 20 foot pipe is required for each hoop on an 18 foot wide design. To make the purlins you have to cut a 20 foot pipe in half then join each half to another 20 foot pipe. When purchasing pipe make sure you get factory flared ends one on each side of each pipe. One straight end fits into the flared end of its partner making the pipe long enough to span the width of your structure. The pipes will fit together pretty solidly but you should still use PVC cement just to make sure everything stays put.
4. Install the purlins: Even though you have your hoops up they are not strong enough without the purlins. These are the horizontal pipes that link the hoops together. Place the purlin pipes in the inside of the hoops and secured with the smooth heads of a ¼ inch in diameter by a 4 inch set of carriage bolts; you need these all facing up.
5. Add and anchor plastic: Apply protective tape along the edges of the frame before you install the poly to prevent premature deterioration of the poly. Use the best grade of greenhouse plastic you can find. Plastic from the hardware store looks nice but it will degrade in sunlight and tear in a couple of years. The best plastic to use is 6ml UV-protected greenhouse plastic. This plastic should last you 4-5 years or more. It will also give you a better thermal performance.
6. Build end walls: For best framing results use 2 x 3 or 2 x 4 lumber for your end walls. Notched pipe saddles secure the end frames to the PVC structure. You can use wooden battens to secure the plastic along the edges of the end wall frames but wiggle wire channels and spring strips that secure the main edges of the plastic will work better.
Follow those easy steps to build a hoop greenhouse and you will end up with a nice quality greenhouse that should last a good 4-5 years without needing any significant maintenance.
The first and immediate advantage of a hoop style greenhouse is the low cost of the PVC and other materials. You can easily build one for under a $100. Hoop greenhouses using plastic rather than glass extend your growing time by 3-4 months. That longer growing season means you can grow a much greater variety of plants. Most growers recoup the cost of building in a single season especially if they build a hoop greenhouse on their own.