We have taken a short break from the house this month to build a small hoop house for ourselves. The main purpose of this 12×28 structure is to give us a place to start seedlings for the farm. However, we also built two 2-foot wide raised beds to grow winter vegetables for us to eat. We drew a lot of our design from Alberta Home Gardening (1, 2), but made a few changes. The main change was to build each hoop out of a single piece of PVC, since the hoop house we were borrowing last year broke at the joints. We tried building a caterpillar tunnel without any joints.
If the first version of the PVC caterpillar looks too weak, well, it was. The day after we finished we had a wind storm with gusts between 40-50mph and two of the hoops broke. We doubled the hoops and added purlins. We’ve had windy days since then and the reinforced hoop house stood up just fine. That was a HUGE relief. Here are step-by-step photos in case you want to build something like this.
1) We laid out the edge of the beds, staked them down, and put in rebar to slip the PVC over.
2) We put a 2-foot leg on each end of each hoop to give us more growing room at the edges, then put the hoop over the rebar and used metal straps to attach the hoop to the frame. (We didn’t want a joint at the top where it would be weak, but there is a lot less stress on the joints at the sides.) Each hoop is made of a 20-ft section of 1″ PVC. 3) Designing the end walls was a challenge for us. We based the end wall design on the design from Alberta Home Gardening (1, 2) and we are pleased with how sturdy the end wall is. The solid end wall does cast shade, so we’ll have to see if that is a problem or not. We used a hoop to trace the shape onto the plywood and used pipe insulation on the edges of the wood to protect the plastic.
4) We bought energy-efficient IR/AC (Infrared/Anti-Condensation) plastic from Farm Tek. The IR/AC plastic is only marginally more expensive than standard plastic and can have a big impact. It was breezy, almost too much to get the plastic on, but we did. We attached the plastic to the end walls using plywood laths.
5) We created the “caterpillar” by pulling 3/16″ polyester rope back and forth in an “X” pattern. It took two ropes, each running the length of the hoop house. We used eye bolts at each hoop to pull the rope through.
So here is Version 1 of our hoop house. It may not have been strong enough, but dang, the caterpillar tunnels look neat and nice. Sadly, it wasn’t rigid enough. With 40-50mpg gusts of wind, the hoops bent all the way down to the ground and broke where they were strapped to the frame.
Lesson Learned: A much more rigid, stronger material is needed for a caterpillar-style hoop house without any purlins connecting the hoops. 6) In order to reinforce the hoop house we added two purlins running the length of the hoop house. We also doubled up every hoop. (We’re not sure if the purlins would have been enough on their own, but we couldn’t take any risks with the wind wreaking more havoc.) We added rebar for the extra hoops and connected each hoop pair with several zip ties. The purlins end in Ts which are strapped to the end walls. The purlins are attached to the hoops with 2″ drywall screws and zip ties.
7) We built doors out of simple frames and ends of plastic. 8) Once the doors were on, we began filling the beds. The beds were sheet mulched with cardboard and newspaper, then filled with layers of leaf mold, top soil, and compost. Mr. Bingley loved having piles of earthy black piles lying around the farm in the winter sun. Now the hoop house is finished. It has survived strong winds at least once since we reinforced it and done well. We will build tables and a heat mat to start our seedlings (we’ll post about that soon). For now, we are excited to have completed this, look forward to starting a bounty of spring flowers and veggies, and can’t wait to eat out of our two new beds, and are eager to get back to working on our house.