Mon 14 Dec 2009
Hoop House Design 2.0
Posted by brooklinemama under food (growing, cooking, preserving) , garden structures , Winter Harvest[8] Comments
Last weekend we finally got the plastic on the hoop house, just in time too, before the first big snowstorm.
A couple of days after the storm something did not look right. Several of the “ribs” were no longer bent. A quick inspection revealed that the snow that had accumulated against the bottom had pressed against the ribs, making them bend in more, tightening the arch. This had put too much force on the pvc cross connectors on top, and several of these had broken.
The house still stood by virtue of the connectors still in place, the plastic covering (which did not tear even at those point where the loose ribs were poking into it), and the milder weather. Yesterday DH and I had a chance to go out and fix it.
The cross connectors can’t stand up to that kind of pressure because they are made of rigid pvc, which may get brittle in the freezing temperatures. Not being able to bend, they just break. So we reinforced each connector with a metal rod. The pressure of the arch is now on the metal rod inside the joint and on the much more bendable pvc of the ribs where the rod’s endpoints press on them.
Hopefully this will do the trick, but to prevent the pressure from building in the first place, we are also creating a cross brace on the most vulnerable side of the hoop house. This will at least give us some extra time to clear away the snow. (More on this later.)
I peeked underneath the row covers and everything is doing well, though the Russian kale looked a bit peekish – next year I will be following the Matron of Husbandry’s tips on winter hardy veggies. I also had the chance to harvest some of our first winter harvest:
Swiss chard, harvested mid-December. So good!
December 14th, 2009 at 10:31 pm
I still have carrots but I can’t pull them up now that the bed is frozen solid. Maybe tomorrow at mid-day? It’s supposed to get near 50′F.
December 16th, 2009 at 9:26 pm
Very interesting. I always say the best way to learn is by doing. I’ve been interested in a hoop house ever since I saw yours. Your experience will be very helpful to others of us. Swiss chard looks absolutely yummy!
December 18th, 2009 at 1:07 pm
The hoop house is an interesting experiment, interesting also as a collaboration between myself and DH, and we don’t always agree on its design. The door, for instance… we’ve tried one door system (it lasted all of half an hour in the rain), and are now pondering a replacement. Will update on that when I come back.
January 3rd, 2010 at 12:20 pm
[...] I am happy to report that the hoop house has withstood heaps of snow and gusts of wind, so our reinforcement of the top connectors seems to be [...]
January 18th, 2010 at 10:27 pm
[...] inside and prop the whole thing up while I cleared away the snow. We got away with only one of the connectors on top breaking and a couple of tears in the plastic cover. What do you think: [...]
February 26th, 2010 at 1:06 pm
[...] I walked out this morning to set things aright before the big snowstorm – we know how the house, even in its better days, performs under snow loads! – I found that it had jumped all of the anchors but one. It had jumped over all of the stakes and [...]
March 12th, 2010 at 9:53 am
[...] pvc pipes for the ribs, so they will be 1 piece across, so no breaking connectors (definitely the weak points in our first design). Rebars are pounded into the ground and the ribs [...]
May 12th, 2010 at 9:15 pm
[...] not hassle free. It simply wasn’t strong enough. Snow load was a problem, which we addressed with a small modification (version 2.0), and lots of timely shoveling. Then the winds came, and we had a couple of close [...]