If the images in this entry have the feel of time-lapse photography it’s because the story of the greenhouse began late last fall and the project was not completed until late April. Such is the way some things go.
We conceived the greenhouse as a dual-use structure, giving us a warm place in which we might extend the growing season but also serving as a space for working on other projects out of the weather. The design was adapted from a shed that is used on the Maine coast for boat storage (called a bow-roof shed).
We opted to build on a 16’ x 12’ footprint. I set the stakes that secure the greenhouse to the ground during the first week of December (before the earth froze solid and put the project off even more!).
Our original plan had been to complete the greenhouse by the end of December but the snows just kept piling up and the winter temperatures rarely warmed beyond the teens. (The photo above was shot a week after Thanksgiving.) Finally, by late-February (below), we had some warm (relative) days and set out to cut and bend the arches.
The frame is made primarily out of 1x3 strapping screwed to four-inch lengths of 2x3 blocking. We used the sill of the greenhouse as a level plane on which to bend the bows – ten of them in all. The bending can be a bit frustrating due to the amount of breakage involved. With each bow there was a long anxious moment as I bent the wood around the form and secured it in place. In all, we experienced a breakage rate of about 25 percent. (Five of the 16-foot lengths of 1x3 snapped while being forced into the curved shape.) We gave up on some days when it felt like the wood was snapping due to the cold, but more likely it was just the pattern of grain and knots in the strapping that led to the failure.
By the end of February we had the ten bows bent and erected the first of the gothic arches. The plywood gussets at the peak hold the bows securely to the 2x4 ridge beam. Once the ten ribs of the frame were in place the project was put on hold again, this time for maple sugarin’ season.
The sap flow finally gave way to budding trees and we boiled our last batch of syrup on April 14th. Time to frame in the ends of the greenhouse, creating openings for the door and vent windows near the peak.
As is the tradition with timber framers over the centuries, we “topped off” the frame with the bough of a tree (called a “whetting bush”). The custom is to use an evergreen species and place it at the highest point in the frame.
Sourcing the greenhouse film to “skin” our greenhouse proved to be a bit of a challenge. For whatever reason, suppliers seemed eager to charge outrageous prices for shipping something that is really not much more than a large sheet of polyethylene plastic. Granted, it has UV protection and anti-condensate layers built in but the 720 square feet of the film that we needed doesn’t weigh more than 20 lbs. We eventually found a source within 50 miles (New London, NH) and drove to pick it up. When I had the film in hand the $100 - $180 shipping fee that other online sources had quoted seemed even more ridiculous! Now all we needed was a wind-free day on which we could pull the film over the frame and secure it in place.
Soon after completion the greenhouse/shed became an indispensable “how did we ever live without it” addition to our Tunbridge land. One final step remains – the addition of automatic vent openers that respond to temperature and open or close the vents at a prescribed level of warmth.