I built a vent door for the low tunnel today!
The door frame was made from 4 2"x4" scraps and a 1/2" PVC pipe from Home Depot. The door was made from 4 warped deck railing balusters and metal hardware to hold it together. It was all inspired by my friend Brit's design. The door opens using a auto-vent opener. The auto-vent opener has a compressed gas cylinder that expands and opens the door when the temperature reaches a certain point. Everything is covered in plastic dropcloth.
Total cost of the project was about $100. The biggest expenses are the auto-vent opener and the plastic film.
- Two eight foot 2x4s (using treated lumber could create some concern about arsenic)
- One eight foot 1x1 (square deck balusters work well for this)
- 4 L brackets
- 2 hinges
- 1 autovent opener
- plastic film (greenhouse film is more resistant to the degrading effects of UV light)
|4. Finish the door frame: Measure the distance between the top board and bottom board and cut two 2x4s to that measured length. These will be the vertical parts of the frame for the door. Screw and glue the parts together.|
|5. Build the door: Use hardware to create a squared door that will properly fit into the frame. Attach the door to the frame with hinges. Staple greenhouse plastic over the door and around the edges of the frame, making sure you do not restrict movement of the door with the plastic.|
|View of the inside of the low tunnel. I transplanted the kale, spinach, and lettuce on 2/17/2013. They are planted in a square-foot-garden configuration.|
|Spinach, kale, and lettuce seedlings growing in the low tunnel. There is snow on the outside of the plastic.|