Well this last weekend saw some pretty strong sustained winds with gusts of over 80km/hr. While most things around the farm seemed to go unharmed and almost nothing but the cat's water dish blew away (it was later recovered), we did end up experiencing one small problem:
Both of our hoop houses where we keep our winter greens and rutabaga warm enough to survive winter suffered damage to the plastic from the wind (oddly enough these two houses have had survived harsher winds over the winter). House 3 above (we only have 2, but the end panels are recycled) suffered the worst damage with the plastic ripping right off the east side for the entire length of the house. House 4 suffered less damage with just some tearing on the bottom near the front as can be seen above. There are also some other smaller tears on house 4 along the top where it rubbed on some exposed steel in the wind.
If you enlarge this picture you can see why we had the problem. Despite being U-bolted to the arches the wooden frame ended up sliding up the arches which relaxed the plastic allowing to flap in the wind, which slid the wood up even higher. Closer inspection has also revealed that the arches seemed to be pushed further into the soil then we had which also slackened the plastic.
In this photo you can see the end wall of house 4 bent in on an angle as it bent the rebar which was holding the top straight. In the next photo you can see an arch I found while taking photos that came out of its rebar anchor....the only one I found but it gives you an idea of the power of the wind.
While disappointing the houses did get nearly to the end of our winter CSA. This next week is warm so we shouldn't have a problem with finishing the season. Hopefully we can fix up house 4 enough to get an early spring crop in there, but the plastic on both houses, which should have lasted 4 years, will need to be replaced this year after only a single season of use. In the end I chalk it up to a learning experience and hopefully we will be able to build a better, stronger hoop house for next winter.