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        2013 EQUIP High Tunnel Program

Progress Report & Log      Back to Study Page

(Note, this page in a work in progress:)March 1, 2013 Initial Assessment: Materials purchased ready for assembly. The project is for a 30' x 72' high tunnel (H.T.) with 5' side walls, double layer plastic, curtain side walls and wood end walls by us. Four bids were taken; two were almost identical at roughly $5,400.00 tax included. Both were very good sturdy units. Some of the lower end units will not stand up during high winds. The other two were a better quality product but the prices were approximately $6,500.00 ea and one of those was on sale. We went with the cheaper one that was in stock, a Zimmerman High Tunnel.

The wood runners for the sides and wood for the end walls including two 36" doors and bag concrete mix for the post totaled just under $1,000.00. I will be installing tow 10' x 12' rolling doors on each end on barn door track to accommodate the tractor. This added approximately $350.00 the two end doors of the high tunnel.

The total erected cost of materials is projected to be almost exactly $7,000.00. All labor by us. We purchased enough irrigation materials and plastic mulch to irrigate the high tunnel for approximately $150.00. The project is now finished: Final cost and production data. A crop production assessment will be posted at the end of each growing year. The log below will just hit the highlights of the assembly. When completed I will compile a video to assist anyone who may be considering a high tunnel of their own.

I assembled and erected almost the entire high tunnel by myself, I cannot recommend this. The times could be cut by 60 to 75% with just one helper. It would eliminate endless trips up and down the ladder, clamping one end so you can attach the other, on and on. Get a helper. I have 40 plus years in construction and engineering and I had problems working alone, if this is your first major project and you try to do it alone you are in trouble.

My high tunnel (H.T.) is 30'x72', your dimensions my vary from the instructions slightly. High tunnels are very forgiving in terms of dimension and alignment. However, errors compound themselves, try to be accurate. Use a string line and level on everything. A 1/4" error on the first bay times 13 post equals 3 1/4" at the other end. This is how people get themselves into situations that are not repairable. Look at completed projects and talk to people who have erected high tunnels before.

Tool List - Center punch, hammers, several 1/8" drill bits, 4 or more quick grip clamps, channel locks, impact driver, cordless drill, powered drill also for drilling because the speed is much higher. cargo strap as long as the width of your H.T., tool belt, sockets for the impact driver to fit all of the nuts and screws, string lines, plumb bob, post lever, 2' and 4' levels, shovels, ladders, scaffolding if you can get it, circular saw, hack saw, sharpies, tape measures, squares, sawhorses, large half round file, plumbers sandpaper, WD-40.

  • Listing the hours for each item was an after thought and I was working alone, they are approximate. With a team your times should be considerably less. Get the site clear and as level as possible before starting anything. Water needs to drain away form the H.T. so a slight slope in the length of the H.T. is beneficial.

  • POST - It took about 6 hrs to drill the post, cut the re-bar, dig the holes, square and level the area and set the four corner post in concrete. Inserting re-bar or a bolt in the bottom of the post ensures the post will not pull out of the concrete under heavy loads. I recommend setting all post in concrete, at minimum set the 3 post on each end to provide stability for the wind load on the end walls.
  • TIP - All the post can be marked at one time by lining up the ends and placing a board across at the appropriate height and spray painting along the edge. This is my ground level, 32", it provides a quick reference point for the string line.

  • High Tunnel Post Anchor
    First load of material Post anchor method

  • SQUARING the H.T. - By using the 3 4 5 method of squaring. Set two corner post on one side. Set a string line between them. Measure down from one corner 40' set a stake. Measure across from that post 30' to where you think the corner should be set a second stake. Now measure between the two stakes. The dimension should be 50'. If not adjust the stake at the corner until you get exactly 30' and 50' on those two sides of the triangle. My unit was 30" x 72" to the outside of the post, set the corner post first and allow the concrete to set overnight so that the string lines can be pulled tight without effecting the polition of the corner post.

  • Post Level Post Height Marker
    Post level, If you don't have one, go buy one Easy way to mark a uniform height on post

  • CENTER POST - It took approx. 8 hours to set in concrete and level with a tractor post hole digger the 22 center post. If the post are not plumb and equally spaced in width you will have a very difficult time setting the trusses on the post. Take the time to get it right.

  • Post Post spacer
    Post set in concrete Jig to space post equally

  • TIP - Remember the post are 2 1/2" in dia. If you start measuring from the center or the side wall be consistent and don't forget the diameter. I set my corner post at 30' x 72' and deducted the pipe diameter in the first bay on each end to then obtain 6' bays for the rest of the H.T. Using a string line on the top and bottom of the post, the post jig and a post level it is easy to get your post aligned and plumb.

  • TRUSS ASSEMBLY - Save your self a lot of headaches and do what I tell you here. Get 4 sets of saw horses and 3 sheets of plywood. Tack the 3 sheets of plywood to three of the sets of sawhorses. In a level area position the 3 tables at each end of the truss and one at the apex. Use the other sawhorse set in the middle to hold the W truss. Level the sawhorses and plywood with blocks and shims. Use this table to assemble your trusses. If the trusses are not extremely flat when assembled they will not fit on the post and none of the bracing will line up correctly. Crooked trusses can also weaken the structure considerably under high wind loads.

  • PIPE - You will note there are burrs inside and on the outside of the pipe where it was cut and the male ends were rolled. This will make sliding them together difficult. Use the half round file to clean the edge of the female pipe ends and the plumbers sandpaper to clean up the edge of the male ends. A spray of WD-40 and they will slide together easily.

  • TRUSS ASSEMBLY - Place the three top truss pieces on the assembly table. Before slipping them together slide all the brackets onto the pipe. This is much easier them trying to spread them apart and then squeeze them back together. Now slip the 3 pieces together. Make sure they lie flat. Use the cargo strap to pull the ends together until they are the exactly the same width as your post are set apart (30" on the outside in my case). Screw the three pieces together, make sure no screws are on top or they will tear the plastic liner. The two end trusses also cannot have screws faceing the endwall plastic. Assemble the lower cross member first. Measure up the same distance from the bottom of the pipe on each side to ensure it will be level when erected. Next assemble the W truss components. Screw all the couplings in place and drill all piolet holes for cross members while the trusses are on the table, it is much easier than working from a ladder. It took a little over 1 hr per truss to assemble and drill all the holes.

  • SETTING the TRUSSES - If you have a tractor and a boom this is a three person job. If not you will need a section of movable scaffolding and at least 4 strong people. File and sand the ends as previously described. Remember the two ends walls do not get the W truss, they will be framed in with either wood or metal studs. Set the trusses on the post, slide the sides down evenly until completely seated. Tapping on the post with a hammer will help move stubborn trusses into position. With a tractor and 3 people setting the trusses took just over 2 hours.

  • BRACES - Put a tek screw in each cross brace bracket to keep them from sliding on the pipe. Install the cross braces on the end trusses. My unit had a stringer for the two end trusses. There will be no truss webbing because of the end wall. You will need to coordinate how you are going to build the end wall with this stringer. As shown I screwed mine to the back side of the end wall. My manufacture recomends 2 tek screws in each of the pipe slip joints, my supplier recommends 3 per joint. I strongly recommend 3 in all locations.

  • TOP RAIL - Install 2x8 lumber along the top of the post first (hip rail). Ensure the post is plumb before attaching to the wood. Do not splice the lumber at the post. The structure will be much stronger if spliced between the post. One method is to start with a 10' piece at the end and then use 12' lumber thereafter. A 32' splice gets you 3 from a 8' board. Put screws thru the clamps into the post and an additional screw into the post to keep them from separating from wind uplift.

  • BOTTOM RAIL - Install 2x6 lumber along the bottom along the ground. Use a string line to keep it level.

  • PULLIES -

  • WIGGLE WIRE TRACK - Screw the wiggle wire track along the top of the 2x8 rail. Screw approximately every 12'.

  • END CAPS -

  • CURTAIN WALL - Start 18" in from the end and start a 1 1/4" roofing nail every 3' for the cord to loop over. Do the same for the bottom rail starting 3' in from the end. Weave the cord on the nails and then drive the nails down tight.

  • CURTAIN PULLIES -

  • -

  • CURTAIN BOTTOM -

  • OUTER CORD - Install eye bolts half way between the nails holding the inner cord web. The outer cord must me loose enough to allow the curtain to fold up and drop down with out restricting it. By using eye bolts top and bottom you can adjust the slack so that the curtain drops without binding. Leave yourself several feet of slack at one end until you get it adjusted.

  • STEEL CABLE -

  • END WALL -

  • END WALL PLASTIC -

  • VENT - Vents at the eaves of the end wall are important. In the spring and fall when the H.T. is closed to prevent frost bite when the sun hits the H.T. the temperature can jump to well over 100 deg. killing your seedlings. The vents can be opened to let the heat, which rises, out.

  • DOORS - Spend the $75 to put at least a personnel door at each end. I also put a 12' wide by 9' high door at each end so that we could drive the tractor or a truck straight thru the H.T. I think in the long run you will be glad you put in all the doors. The extra cost is minimal. At least build the end walls with the doors framed in so that in the future all you have to do is cut the plastic and attach a door.

  • PLASTIC ROOF -

  • PLYWOOD LINER - We are spending the money to line the ends with plywood. This not only protects the plastic from accidental puncture but gives us a place to hang some hand tools, and mount irrigation equipment and future solar controllers and temperature sensors.

  • TIP - Drainage - One issue people do not think about is drainage. All the water that hits the H.T. roof has to go somewhere. Make sure it can drain away. Many people have problems because the sides stay too wet to grow crops.



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    2013 Rocky Creek Valley Farm

    Disclaimer: Read and follow manufactures instructions and follow all local buillding codes. RCV Farm is making no design calculation this information is merely to assist the user in the assembly of the high tunnel where manufactures instructions my be vague or lacking. - See full legal disclosure
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