After trying a lot of different housing options for the worms, I decided that the best option in my case is to use hoop style greenhouse buildings. Hoop houses, as they are often called, are semi-circular buildings made from curved semi-circle rafters and are usually covered by clear poly-ethylene film. Not only are these buildings strong, but they are also inexpensive compared to other structures; furthermore, the hoop house can be covered in poly during the winter and then covered with shade cloth for summer use.
The main structural components of the building are the rafters, also called hoops. These can be made of wood, steel, or even pvc pipe. I recommend the use of steel pipe covered in a rust proof coating. EMT conduit is widely available and relatively inexpensive. It is used to route electrical wires in buildings and can be purchased at electrical supply houses and at many well known home improvement stores. The other main structural components are the purlins. Purlins run the length of the hoop house and tie the rafters together. They are commonly between 1 and 5 purlins in a hoop house, but I would recommend at least 3. Purlins not only add extra rigidity to the building, but can be used as anchors for lights, fans, sprinklers, or hanging plants and other items on. The size and spacing of the purlins and rafters is going to depend largely upon the size of the building and the expected snow load. Also if you do intend to hang plants or other items off of the purlins to make sure they are plenty strong for that as well.
An average rafter spacing for commercially available hoop greenhouse is about 6′. I personally believe this to be to far apart and like to space the rafters no further than 4′ apart. Although this may add a little cost to the building, but I can sleep sound at night during heavy snow and freezing rain knowing that my greenhouse is plenty strong.
The hoop house is anchored to the ground using ground post. The ground post are simply pipes that are driven into the ground that the rafters will attach to. EMT conduit may be used for these as well. In my location the pipes were driven about 3′ deep, but the required depth will depend upon your soil.
This covers the basics of hoop houses, but soon I will be posting the details of an actual hoop house construction that is sure to keep some wiggler worms happy. Also I am looking forward to having a place to grow plants in the winter and having a good building for researching potting soils made with worm castings.
Thanks for reading,