Friday, April 17, 2009

hoophouse construction part 1 (of 5)

I've been looking for a hoophouse for a while; I've got an area that isn't very good pasture, and a greenhouse is a pretty versatile structure. You can brood birds in it, shelter breeding flocks, grown plants, all sorts of things. So when I saw a fellow about 100 miles away that was selling 30'x96' greenhouses for $1,000, I bought two.
Here's my trailer loaded with the frames, members, plastic and channel for the greenhouses. I figure the load is about 3,000lbs.
Here's the area that we're going to lay out the greenhouse on. The specs say 30'x96', but I'm a bit of a skeptic. So we place the corner posts, and then assemble one of the trusses to put it in place to make sure that it's really 30' and everything fits.

This little laser level allows me to check the level across the structure, from the top of each post to the top of the other. I can also check level front to back. To make sure that the structure is square, after the rough layout was done, I drove two of the corner posts and then used a piece of twine to do a diagonal measurement, and then drove the other two corners. After that, I measured again to ensure square. Square and plumb is important for best structural strength.

Here the first truss is set into place. Yes, it's 30' wide. This house was originally set up with 4' posts, driven 2' into the ground. That gave you a clearance of 9' to the bottom of the truss. My tractor is 9' tall, and I'd like to be able to drive my tractor into this structure to deliver materials, so I purchased 8' posts, and drove them 5' into the ground. This leaves 3' exposed, and gives me a height of 10' to the bottom of the truss -- so my tractor will fit.

The hoops on this particular house are spaced 4' apart. Here we've driven every other post, and mounted the first truss. This structure is bigger than it looks in the picture; I'm erected both of these hoophouses end-to-end, so I'll end up with 6,000 square feet under roof, approximately 30' wide and 200 feet long.

County regulations require a setback from the property lines of 25' for structures that might house animals, so I've set this structure 26' from both the side and and back property lines as a precautionary measure. When you take down the hoophouse you ruin the plastic; so this ensures that if there is an issue the setback won't be something they can bug me about. It's considered a temporary structure so there should not be an issue.
My land is river bottom, so there's no rocks to deal with. I used 8' posts driving 5' deep to provide both anchorage in the event of a flood, and plenty of friction to allow the frame to resist being pushed into the ground by snow load.


Anonymous said...

So fun to watch an engineer at work. Very logical and well thought out. I saw the ad, I so want one, but it ain't gonna happen right now. Where you gonna get your plastic? There's a place in ND that sells sun resistant plastic for greenhouses. 204 437 5540
or do you have a local source?

Anonymous said...

Where's the finished photo?? I built a smaller one of these in New Zealand and I miss it terribly. Lucky you!


Cat parking lot said...

To who ever might have an Idea! I was reading the green house blog and thinking about a military parachute I left in my yard for several days. I noticed it begain rising and found the grass under the chute had grown twice as fast as the area not coverd.
I'm not sure why but I'm really interested in knowing, since I have more 500,000 square feet of this materiel.