Sunday
Apr102011
Building a High Tunnel Hoop House / Green House : Part 2
Sunday, April 10, 2011 at 6:46AM
Just to set the record straight before we get into this... The last post on Pigs Milk Cheese was an April Fools post (nice job to those who caught the date). Also - if you haven't ordered your pastured chicken yet - you should.
With the posts in the ground (from the first post) there's still a fair amount of work to be done, we needed to get a wooden base around to frame up an attachment point for the double layer of plastic. We also need to get the hoops installed, the spine installed and then some nifty wind bracing installed so we have a prayer of sustaining those 60 MPH+ winds we get on the hill here without watching our hard work blow into the next county. So we started with the base boards. normally people install larger treated 2x something boards - but looking at the price of lumber we decided to go with a much less expensive treated 5/4x6 non-premium decking board. In reality, these base boards don't offer much more that a place to attach the plastic so there's no need to them to be super heavy duty. They are attached by drilling a hole through the board and the post and then attaching with a 1/4" stainless bolt and nut.
The challenge of installing the the base boards is really all about level ground. The posts were driven in to an approximation of "level" - but adding the base boards required a fair amount of finagling. All said and done, the lower end of the structure has the baseboard about 4" above the soil and te high end has the boards about 3" into the soil. And we picked one of the more level areas to site the greenhouse!
With 3 sides of the base completed (we left the end with the door open as it cuts through the existing low tunnel AND we are still debating about making the end door tractor friendly as well) it was time to start to assemble the superstructure, and all that starts with an end. So, we used the backhoe to dig a couple of 3' deep holes and dropped some old treated 2x4's in. Those were then lined up with the end hoop, cut to length, notched and bolted to the hoop itself. The spacing for the end posts we determined by the 2 tripple track storm windows that came off the barn when we resided it. They are big and will provide LOTS of ventilation on the west end of the green house.
Once that "wall" was built, the process really takes off. It becomes an exercise in joining the 2 halves of the hoops we bent with stainless self tapping metal screws, then inserting them into the posts that are attached to the base boards. After all the hoops are up, the next step was to use some special (and expensive) clamps designed to attach the spine down the top ridge line. This addition locks all the hoops into a single structure and really provides a massive amount of rigidity to the structure. Up until this point we kinda felt like we were kids making a sandcastle at low tide... just waiting for the wind to pick up and blow out wiggly metal structure into 100 little pieces. But with each rib being attached to the spine (yes, I loved Moby Dick), the whale of a structure became more and more solid.
After the last section of the spine was installed and cut to length all we had left todo was install a set of diagonal wind braces and the windows. All in all, the steps in this part of the installation only took about 5 hours over 2 days and were the most rewarding steps. We can now stand back and look at something that resembles a green house. And the most rewarding part has been the discovery of how strong this structure really is. The spine and the wind bracing has made the and wall solid and we really think this structure is going to be able to take the winds. As a matter of fact we are already thinking of LOTS of ways we can expand this design for something like a roaming pasture warmer for the chickens in the middle of winter... At any rate, tonight we place the order for the plastic, inflator fan and various other parts. Time marches on and our seedlings in the basement are getting ready for a nice warm "real sunlight" house!
For a few more pictures of the process - visit our Flickr Photostream to check things out.
With the posts in the ground (from the first post) there's still a fair amount of work to be done, we needed to get a wooden base around to frame up an attachment point for the double layer of plastic. We also need to get the hoops installed, the spine installed and then some nifty wind bracing installed so we have a prayer of sustaining those 60 MPH+ winds we get on the hill here without watching our hard work blow into the next county. So we started with the base boards. normally people install larger treated 2x something boards - but looking at the price of lumber we decided to go with a much less expensive treated 5/4x6 non-premium decking board. In reality, these base boards don't offer much more that a place to attach the plastic so there's no need to them to be super heavy duty. They are attached by drilling a hole through the board and the post and then attaching with a 1/4" stainless bolt and nut.The challenge of installing the the base boards is really all about level ground. The posts were driven in to an approximation of "level" - but adding the base boards required a fair amount of finagling. All said and done, the lower end of the structure has the baseboard about 4" above the soil and te high end has the boards about 3" into the soil. And we picked one of the more level areas to site the greenhouse!
With 3 sides of the base completed (we left the end with the door open as it cuts through the existing low tunnel AND we are still debating about making the end door tractor friendly as well) it was time to start to assemble the superstructure, and all that starts with an end. So, we used the backhoe to dig a couple of 3' deep holes and dropped some old treated 2x4's in. Those were then lined up with the end hoop, cut to length, notched and bolted to the hoop itself. The spacing for the end posts we determined by the 2 tripple track storm windows that came off the barn when we resided it. They are big and will provide LOTS of ventilation on the west end of the green house.
Once that "wall" was built, the process really takes off. It becomes an exercise in joining the 2 halves of the hoops we bent with stainless self tapping metal screws, then inserting them into the posts that are attached to the base boards. After all the hoops are up, the next step was to use some special (and expensive) clamps designed to attach the spine down the top ridge line. This addition locks all the hoops into a single structure and really provides a massive amount of rigidity to the structure. Up until this point we kinda felt like we were kids making a sandcastle at low tide... just waiting for the wind to pick up and blow out wiggly metal structure into 100 little pieces. But with each rib being attached to the spine (yes, I loved Moby Dick), the whale of a structure became more and more solid.
After the last section of the spine was installed and cut to length all we had left todo was install a set of diagonal wind braces and the windows. All in all, the steps in this part of the installation only took about 5 hours over 2 days and were the most rewarding steps. We can now stand back and look at something that resembles a green house. And the most rewarding part has been the discovery of how strong this structure really is. The spine and the wind bracing has made the and wall solid and we really think this structure is going to be able to take the winds. As a matter of fact we are already thinking of LOTS of ways we can expand this design for something like a roaming pasture warmer for the chickens in the middle of winter... At any rate, tonight we place the order for the plastic, inflator fan and various other parts. Time marches on and our seedlings in the basement are getting ready for a nice warm "real sunlight" house!
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For a few more pictures of the process - visit our Flickr Photostream to check things out.
tagged construction, greenhouse, high tunnel, hoop, hoop house in Farm Life, Gardening, How To
construction, greenhouse, high tunnel, hoop, hoop house in Farm Life, Gardening, How To
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