I posted the failure on Facebook. Some of my friends consoled me. Others offered suggestions. I was already thinking about building a sturdier cross piece, something like a light structural beam, and many of my friends offered similar suggestions. Then my son, Boston, suggested a different approach:
"I think a compression member is asking for trouble. Why not a thick, strong rope under tension instead of a beam? Keep the 4x4 posts at the gable ends for compression, and turnbuckle the beam rope on the ground. Less weight over your head if it fails, too."
As soon as I read his post I knew he was on the right track.
I drilled 1/2" holes at the top of each 4x4 post and ran 50' of 1/2" twisted nylon rope from post to post. The rope has a 600 lbs working load. I intended to put 200 lbs of tension on the rope to keep it flat. That would leave 400 lbs for snow load.
I drilled 1/2" holes at the top of each 4x4 post and ran 50' of 1/2" twisted nylon rope from post to post. The rope has a 600 lbs working load. I intended to put 200 lbs of tension on the rope to keep it flat. That would leave 400 lbs for snow load.
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| Sighting down the rope from the front post, 14 feet off the ground |
I staked the ends of the rope to the ground using two, 2 1/2' x 3/4" pipes at each end, and rigged a sort of block-and-tackle on the rope using four D-rings. I pulled the rope taut.
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| Block-and-tackle made from D-rings |
The block-and-tackle worked well and I was able to get the rope pretty flat, which in turn keeps the rain fly smooth and stationary.
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| Rope in place, anchored, and pulled taut |
I draped the rain fly over the rope and staked it down.
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| The finished rain fly |
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