The grand finale!
We used a Poly Keder called SolaWrap to cover the greenhouse rather than standard polyethylene film. SolaWrap is a film cladding system that has been used in Europe for a number of years but was not available in the U.S. until 2013. It is engineered to both insulate and diffuse sunlight, retaining up to 95 percent of heat radiation while providing an R-value of 1.7. The Keder locking mechanism is water and air tight and is strong enough to withstand our extreme weather conditions. We were also attracted by SolaWrap's long lifespan of 20-25 years or more.
Our greenhouse was constructed by Vine Ripe Greenhouse construction (https://www.vineripe.net/). We provided most of our own labor, which helped reduce costs and turned out to be a great learning opportunity.